Keeping up with current evidence-based healthcare practices is key to providing good clinical care to patients. This review presents 5 vignettes that highlight key issues in women’s health: osteoporosis screening, hormonal contraceptive interactions with antibiotics, hormone replacement therapy in carriers of the BRCA1 gene mutation, risks associated with hormonal contraception, and breast cancer diagnosis using digital tomosynthesis in addition to digital mammography. Supporting articles, all published in 2017 and 2018, were selected from high-impact medical and women’s health journals.

OSTEOPOROSIS SCREENING FOR FRACTURE PREVENTION

A 60-year-old woman reports that her last menstrual period was 7 years ago. She has no history of falls or fractures, and she takes no medications. She smokes 10 cigarettes per day and drinks 3 to 4 alcoholic beverages on most days of the week. She is 5 feet 6 inches (170 cm) tall and weighs 107 lb. Should she be screened for osteoporosis?

Osteoporosis is underdiagnosed

It is estimated that, in the United States, 12.3 million individuals older than 50 will develop osteoporosis by 2020. Missed opportunities to screen high-risk individuals can lead to fractures, including fractures of the hip.¹

Updated screening recommendations

In 2018, the US Preventive Services Task Force (USPSTF) developed and published evidence-based recommendations for osteoporosis screening to help providers identify and treat osteoporosis early to prevent fractures.² Available evidence on screening and treatment in women and men were reviewed with the intention of updating the 2011 USPSTF recommendations. The review also evaluated risk assessment tools, screening intervals, and efficacy of screening and treatment in various subpopulations.

Since the 2011 recommendations, more data have become available on fracture risk assessment with or without bone mineral density measurements. In its 2018 report, the USPSTF recommends that postmenopausal women younger than 65 should undergo screening with a bone density test if their 10-year risk of major osteoporotic fracture is more than 8.4%. This is equivalent to the fracture risk of a 65-year-old white woman with no major risk factors for fracture (grade B recommendation—high certainty that the benefit is moderate, or moderate certainty that the benefit is moderate to substantial).²

Assessment of fracture risk

For postmenopausal women who are under age 65 and who have at least 1 risk factor for fracture, it is reasonable to use a clinical risk assessment tool to determine who should undergo screening with bone mineral density measurement. Risk factors associated with an increased risk of osteoporotic fractures include a parental history of hip fracture, smoking, intake of 3 or more alcoholic drinks per day, low body weight, malabsorption, rheumatoid arthritis, diabetes, and postmenopausal status (not using estrogen replacement). Medications should be carefully reviewed for those that can increase the risk of fractures, including steroids and antiestrogen treatments.

The 10-year risk of a major osteoporotic or hip fracture can be assessed using the Fractional Risk Assessment Tool (FRAX), available at www.sheffield.ac.uk/FRAX/. Other acceptable tools that perform similarly to FRAX include the Osteoporosis Risk Assessment Instrument (ORAI) (10 studies; N = 16,780), Osteoporosis Index of Risk (OSIRIS) (5 studies; N = 5,649), Osteoporosis Self-Assessment Tool (OST) (13 studies; N = 44,323), and Simple Calculated Osteoporosis Risk Estimation (SCORE) (8 studies; N = 15,362).

Should this patient be screened for osteoporosis?

Based on the FRAX, this patient’s 10-year risk of major osteoporosis fracture is 9.2%. She would benefit from osteoporosis screening with a bone density test.

DO ANTIBIOTICS REDUCE EFFECTIVENESS OF HORMONAL CONTRACEPTION?

A 27-year-old woman presents with a dog bite on her right hand and is started on oral antibiotics. She takes an oral contraceptive that contains 35 µg of ethinyl estradiol and 0.25 mg of norgestimate. She asks if she should use condoms while taking antibiotics.

The antibiotics rifampin and rifabutin are known inducers of the hepatic enzymes required for contraceptive steroid metabolism, whereas other antibiotics are not. Despite the lack of compelling evidence that broad-spectrum antibiotics interfere with the efficacy of hormonal contraception, most pharmacists recommend backup contraception for women who use concomitant antibiotics.³ This practice could lead to poor compliance with the contraceptive regimen, the antibiotic regimen, or both.³

Simmons et al³ conducted a systematic review of randomized and nonrandomized studies that assessed pregnancy rates, breakthrough bleeding, ovulation suppression, and hormone pharmacokinetics in women taking oral or vaginal hormonal contraceptives in combination with nonrifamycin antibiotics, including oral, intramuscular, and intravenous forms. Oral contraceptives used in the studies included a range of doses and progestins, but lowest-dose pills, such as those containing less than 30 µg ethinyl estradiol or less than 150 µg levonorgestrel, were not included.

The contraceptive formulations in this systematic review³ included oral contraceptive pills, emergency contraception pills, and the contraceptive vaginal ring. The effect of antibiotics on other nonoral contraceptives, such as the transdermal patch, injectables, and progestin implants was not studied.

Four observational studies³ evaluated pregnancy rates or hormonal contraception failure with any antibiotic use. In 2 of these 4 studies, there was no difference in pregnancy rates in women who used oral contraceptives with and without nonrifamycin antibiotics. However, ethinyl estradiol was shown to have increased clearance when administered with dirithromycin (a macrolide).³ Twenty-five of the studies reported measures of contraceptive effectiveness (ovulation) and pharmacokinetic outcomes.

There were no observed differences in ovulation suppression or breakthrough bleeding in any study that combined hormonal contraceptives with an antibiotic. Furthermore, there was no significant decrease in progestin pharmacokinetic parameters during coadministration with an antibiotic.³ Study limitations included small sample sizes and the observational nature of the data.

How would you counsel this patient?

Available evidence suggests that nonrifamycin antibiotics do not diminish the effectiveness of the vaginal contraceptive ring or an oral hormonal contraceptive that contains at least 30 µg of ethinyl estradiol or 150 µg of levonorgestrel. Current guidelines do not recommend the use of additional backup contraception, regardless of hormonal contraception dose or formulation.⁴ Likewise, the most recent guidance for dental practitioners (ie, from 2012) no longer advises women to use additional contraceptive protection when taking nonrifamycin antibiotics.⁵

In our practice, we discuss the option of additional protection when prescribing formulations with lower estrogen doses (< 30 µg), not only because of the limitations of the available data, but also because of the high rates of unintended pregnancy with typical use of combined hormonal contraceptives (9% per year, unrelated to use of antibiotics).⁴ However, if our patient would rather not use additional barrier methods, she can be reassured that concomitant nonrifamycin antibiotic use is unlikely to affect contraceptive effectiveness.

 

 

HORMONE REPLACEMENT THERAPY IN CARRIERS OF THE BRCA1 MUTATION

A 41-year-old healthy mother of 3 was recently found to be a carrier of the BRCA1 mutation. She is planning to undergo prophylactic bilateral salpingo-oophorectomy for ovarian cancer prevention. However, she is apprehensive about undergoing surgical menopause. Should she be started on hormone replacement therapy after oophorectomy? How would hormone replacement therapy affect her risk of breast cancer?

In females who carry the BRCA1 mutation, the cumulative risk of both ovarian and breast cancer approaches 44% (95% confidence interval [CI] 36%–53%) and 72% (95% CI 65%–79%) by age 80.⁶ Prophylactic salpingo-oophorectomy reduces the risk of breast cancer by 50% and the risk of ovarian cancer by 90%. Unfortunately, premature withdrawal of ovarian hormones has been associated with long-term adverse effects including significant vasomotor symptoms, decreased quality of life, sexual dysfunction, early mortality, bone loss, decline in mood and cognition, and poor cardiovascular outcomes.⁷ Many of these effects can be avoided or lessened with hormone replacement therapy.

Kotsopoulos et al⁸ conducted a longitudinal, prospective analysis of BRCA1 mutation carriers in a multicenter study between 1995 and 2017. The mean follow-up period was 7.6 years (range 0.4–22.1). The study assessed associations between the use of hormone replacement therapy and breast cancer risk in carriers of the BRCA1 mutation who underwent prophylactic salpingo-oophorectomy. Study participants did not have a personal history of cancer. Those with a history of prophylactic mastectomy were excluded.

Participants completed a series of questionnaires every 2 years, disclosing updates in personal medical, cancer, and reproductive history. The questionnaires also inquired about the use of hormone replacement therapy, including the type used (estrogen only, progestin only, estrogen plus progestin, other), brand name, duration of use, and dose and route of administration (pill, patch, suppository).

Of the 13,087 BRCA1 mutation carriers identified, 872 met the study criteria. Of those, 377 (43%) reported using some form of hormone replacement therapy after salpingo-oophorectomy, and 495 (57%) did not. The average duration of use was 3.9 years (range 0.5–19), with most (69%) using estrogen alone; 18% used other regimens, including estrogen plus progestin and progestin only. A small percentage of participants did not indicate which formulation they used. On average, women using hormone replacement therapy underwent prophylactic oophorectomy earlier than nonusers (age 43.0 vs 48.4; absolute difference 5.5 years, P < .001).

During follow-up, there was no significant difference noted in the proportion of women diagnosed with breast cancer between hormone replacement therapy users and nonusers (10.3 vs 10.7%; absolute difference 0.4%; P = .86). In fact, for each year of estrogen-containing hormone replacement therapy, there was an 18% reduction in breast cancer risk when oophorectomy was performed before age 45 (95% CI 0.69–0.97). The authors also noted a nonsignificant 14% trend toward an increase in breast cancer risk for each year of progestin use after oophorectomy when surgery was performed before age 45 (95% CI 0.9–1.46).

Although prophylactic hysterectomy was not recommended, the authors noted that hysterectomy would eliminate the need for progestin-containing hormone replacement therapy. For those who underwent oophorectomy after age 45, hormone replacement therapy did not increase or decrease the risk of breast cancer.⁷

A meta-analysis by Marchetti et al⁹ also supports the safety of hormone replacement therapy after risk-reducing salpingo-oophorectomy. Three studies that included 1,100 patients were analyzed (including the Kotsopoulos study⁸ noted above). There was a nonsignificant decrease in breast cancer risk in women on estrogen-only hormone replacement therapy compared with women on estrogen-plus-progestin therapy (odds ratio 0.53, 95% CI 0.25–1.15). Overall, the authors regarded hormone replacement therapy as a safe therapeutic option after prophylactic salpingo-oophorectomy in carriers of the BRCA1 and BRCA2 mutations.⁹

In a case-control study published in 2016,¹⁰ hormone replacement therapy was assessed in 432 postmenopausal BRCA1 mutation carriers with invasive breast cancer (cases) and in 432 BRCA1 mutation carriers without a history of breast cancer (controls). Results showed no difference in breast cancer risk between hormone replacement therapy users and nonusers.¹⁰

Rebbeck et al¹¹ evaluated short-term hormone replacement therapy in BRCA1 and BRCA2 gene-mutation carriers after they underwent prophylactic salpingo-oophorectomy. The results showed that hormone replacement did not affect the breast cancer risk-reduction conferred with prophylactic bilateral salpingo-oophorectomy.

Johansen et al¹² evaluated hormone replacement therapy in premenopausal women after prophylactic salpingo-oophorectomy. They studied 324 carriers of BRCA gene mutations after they underwent prophylactic salpingo-oophorectomy and a subset of 950 controls who had bilateral salpingo-oophorectomy for reasons unrelated to cancer. In both groups, hormone replacement therapy was underutilized. The authors recommended using it when clinically indicated.

Should your patient start hormone replacement therapy?

This patient is healthy, and in the absence of contraindications, systemic hormone replacement therapy after prophylactic oophorectomy could mitigate the potential adverse effects of surgically induced menopause. The patient can be reassured that estrogen-containing short-term hormone replacement therapy is unlikely to increase her breast cancer risk.

 

 

HORMONAL CONTRACEPTION AND THE RISK OF BREAST CANCER

A 44-year-old woman presents to your office for an annual visit. She is sexually active but does not wish to become pregnant. She has a family history of breast cancer: her mother was diagnosed at age 53. She is interested in an oral contraceptive to prevent pregnancy and acne. However, she is nervous about being on any contraceptive that may increase her risk of breast cancer.

To date, studies assessing the effect of hormonal contraception on the risk of breast cancer have produced inconsistent results. Although most studies have shown no associated risk, a few have shown a temporary 20% to 30% increased risk of breast cancer during use.^13,14 Case-controlled studies that reported an association between hormonal contraception and breast cancer included populations taking higher-dose combination pills, which are no longer prescribed. Most studies do not evaluate specific formulations of hormonal contraception, and little is known about effects associated with intrauterine devices or progestin-only contraception.

A prospective study performed by Mørch et al¹³ followed more than 1 million reproductive-aged women for a mean of 10.9 years. The Danish Cancer Registry was used to identify cases of invasive breast cancer. Women who used hormonal contraceptives had a relative risk of breast cancer of 1.20 compared with women not on hormonal contraception (95% CI 1.14–1.26). The study suggested that those who had been on contraceptive agents for more than 5 years had an increased risk and that this risk remained for 5 years after the agents were discontinued. Conversely, no increased risk of cancer was noted in those who used hormonal contraception for less than 5 years. No notable differences were seen among various formulations.

For women using the levonorgestrel-containing intrauterine device, the relative risk of breast cancer was 1.21 (95% CI 1.11–1.33). A few cancers were noted in those who used the progestin-only implant or those using depot medroxyprogesterone acetate. While the study showed an increased relative risk of breast cancer, the absolute risk was low—13 cases per 100,000, or approximately 1 additional case of breast cancer per 7,690 per year.¹³

This study had several important limitations. The authors did not adjust for common breast cancer risk factors including age at menarche, alcohol use, or breastfeeding. Additionally, the study did not account for the use of hormonal contraception before the study period and conversely, did not account for women who may have stopped taking their contraceptive despite their prescribed duration. The frequency of mammography was not explicitly noted, which could have shifted results for women who had more aggressive screening.

It is also noteworthy that the use of high-dose systemic progestins was not associated with an increased risk, whereas the levonorgestrel intrauterine device, which contains only 1/20th the dose of a low-dose oral contraceptive pill, was associated with an increased risk. This discrepancy in risk warrants further investigation, and clinicians should be aware that this inconsistency needs validation before changing clinical practice.

In an observational cohort study,¹⁵ more than 100,000 women ages 50 to 71 were followed prospectively for 15 years to evaluate the association between hormonal contraceptive use and the risk of gynecologic and breast cancers. In this study, the duration of hormonal contraceptive use, smoking status, alcohol use, body mass index, physical activity, and family history of cancer were recorded. Long-term hormonal contraceptive use reduced ovarian and endometrial cancer risks by 40% and 34%, respectively, with no increase in breast cancer risk regardless of family history.

How would you counsel the patient?

The patient should be educated on the benefits of hormonal contraception that extend beyond pregnancy prevention, including regulation of menses, improved acne, decreased risk of endometrial and ovarian cancer, and likely reductions in colorectal cancer and overall mortality risk.^13–16 Further, after their own systematic review of the data assessing risk of breast cancer with hormonal contraception, the US Centers for Disease Control and Prevention state in their guidelines that all contraceptives may be used without limitation in those who have a family history of breast cancer.⁴ Any potential increased risk of breast cancer in women using hormonal contraception is small and would not outweigh the benefits associated with use.

One must consider the impact of an unintended pregnancy in such women, including effects on the health of the fetus and mother. Recent reports on the increasing rates of maternal death in the US (23.8 of 100,000 live births) serve as a reminder of the complications that can arise with pregnancy, especially if a mother’s health is not optimized before conception.¹⁷

 

 

MAMMOGRAPHY PLUS TOMOSYNTHESIS VS MAMMOGRAPHY ALONE

The same 44-year-old patient now inquires about screening for breast cancer. She is curious about 3-dimensional mammography and whether it would be a better screening test for her.

Digital breast tomosynthesis (DBT) is a newer imaging modality that provides a 3-dimensional reconstruction of the breast using low-dose x-ray imaging. Some studies have shown that combining DBT with digital mammography may be superior to digital mammography alone in detecting cancers.¹⁸ However, digital mammography is currently the gold standard for breast cancer screening and is the only test proven to reduce mortality.^18,19

In a retrospective US study of 13 medical centers,²⁰ breast cancer detection rates increased by 41% the year after DBT was introduced, from 2.9 to 4.1 per 1,000 cases. DBT was associated with 16 fewer patients recalled for repeat imaging out of 1,000 women screened (as opposed to mammography alone). Two European studies similarly suggested an increase in cancer detection with lower recall rates.^21,22

Is 3-D mammography a better option?

In a 2-arm study by Pattacini et al,¹⁸ nearly 20,000 women ages 45 to 70 were randomized to undergo either digital mammography or digital mammography plus DBT for primary breast cancer screening. Women were enrolled over a 2-year period and were followed for 4.5 years, and the development of a primary invasive cancer was the primary end point. Recall rates, reading times, and radiation doses were also compared between the 2 groups.

Overall, the cancer detection rate was higher in the digital mammography plus DBT arm compared with digital mammography alone (8.6 vs 4.5 per 1,000). The detection rates were higher in the combined screening group among all age subgroups, with relative risks ranging from 1.83 to 2.04 (P = .93). The recall rate was 3.5% in the 2 arms, with relative risks ranging from 0.93 to 1.11 (P = .52). There was a reduction in the number of false positives seen in women undergoing digital mammography plus DBT when compared with digital mammography alone, from 30 per 1,000 to 27 per 1,000.

Detection of ductal carcinoma in situ increased in the experimental arm (relative detection 2.80, 95% CI 1.01–7.65) compared with invasive cancers. Comparing radiation, the dose was 2.3 times higher in those who underwent digital mammography plus DBT. The average reading times for digital mammography alone were 20 to 85 seconds; adding DBT added 35 to 81 seconds.¹⁹

Should you advise 3-D mammography?

The patient should be educated on the benefits of both digital mammography alone and digital mammography plus DBT. The use of digital mammography plus DBT has been supported in various studies and has been shown to increase cancer detection rates, although data are still conflicting regarding recall rates.^19,20 More studies are needed to determine its effect on breast cancer morality.

Routine use of DBT in women with or without dense breast tissue has not been recommended by organizations such as the USPSTF and the American College of Obstetricians and Gynecologists.^23,24 While there is an increased dose of radiation, it still falls below the US Food and Drug Administration limits and should not be the sole barrier to use.

Keeping up with current evidence-based healthcare practices is key to providing good clinical care to patients. This review presents 5 vignettes that highlight key issues in women’s health: osteoporosis screening, hormonal contraceptive interactions with antibiotics, hormone replacement therapy in carriers of the BRCA1 gene mutation, risks associated with hormonal contraception, and breast cancer diagnosis using digital tomosynthesis in addition to digital mammography. Supporting articles, all published in 2017 and 2018, were selected from high-impact medical and women’s health journals.

OSTEOPOROSIS SCREENING FOR FRACTURE PREVENTION

A 60-year-old woman reports that her last menstrual period was 7 years ago. She has no history of falls or fractures, and she takes no medications. She smokes 10 cigarettes per day and drinks 3 to 4 alcoholic beverages on most days of the week. She is 5 feet 6 inches (170 cm) tall and weighs 107 lb. Should she be screened for osteoporosis?

Osteoporosis is underdiagnosed

It is estimated that, in the United States, 12.3 million individuals older than 50 will develop osteoporosis by 2020. Missed opportunities to screen high-risk individuals can lead to fractures, including fractures of the hip.¹

Updated screening recommendations

In 2018, the US Preventive Services Task Force (USPSTF) developed and published evidence-based recommendations for osteoporosis screening to help providers identify and treat osteoporosis early to prevent fractures.² Available evidence on screening and treatment in women and men were reviewed with the intention of updating the 2011 USPSTF recommendations. The review also evaluated risk assessment tools, screening intervals, and efficacy of screening and treatment in various subpopulations.

Since the 2011 recommendations, more data have become available on fracture risk assessment with or without bone mineral density measurements. In its 2018 report, the USPSTF recommends that postmenopausal women younger than 65 should undergo screening with a bone density test if their 10-year risk of major osteoporotic fracture is more than 8.4%. This is equivalent to the fracture risk of a 65-year-old white woman with no major risk factors for fracture (grade B recommendation—high certainty that the benefit is moderate, or moderate certainty that the benefit is moderate to substantial).²

Assessment of fracture risk

For postmenopausal women who are under age 65 and who have at least 1 risk factor for fracture, it is reasonable to use a clinical risk assessment tool to determine who should undergo screening with bone mineral density measurement. Risk factors associated with an increased risk of osteoporotic fractures include a parental history of hip fracture, smoking, intake of 3 or more alcoholic drinks per day, low body weight, malabsorption, rheumatoid arthritis, diabetes, and postmenopausal status (not using estrogen replacement). Medications should be carefully reviewed for those that can increase the risk of fractures, including steroids and antiestrogen treatments.

The 10-year risk of a major osteoporotic or hip fracture can be assessed using the Fractional Risk Assessment Tool (FRAX), available at www.sheffield.ac.uk/FRAX/. Other acceptable tools that perform similarly to FRAX include the Osteoporosis Risk Assessment Instrument (ORAI) (10 studies; N = 16,780), Osteoporosis Index of Risk (OSIRIS) (5 studies; N = 5,649), Osteoporosis Self-Assessment Tool (OST) (13 studies; N = 44,323), and Simple Calculated Osteoporosis Risk Estimation (SCORE) (8 studies; N = 15,362).

Should this patient be screened for osteoporosis?

Based on the FRAX, this patient’s 10-year risk of major osteoporosis fracture is 9.2%. She would benefit from osteoporosis screening with a bone density test.

DO ANTIBIOTICS REDUCE EFFECTIVENESS OF HORMONAL CONTRACEPTION?

A 27-year-old woman presents with a dog bite on her right hand and is started on oral antibiotics. She takes an oral contraceptive that contains 35 µg of ethinyl estradiol and 0.25 mg of norgestimate. She asks if she should use condoms while taking antibiotics.

The antibiotics rifampin and rifabutin are known inducers of the hepatic enzymes required for contraceptive steroid metabolism, whereas other antibiotics are not. Despite the lack of compelling evidence that broad-spectrum antibiotics interfere with the efficacy of hormonal contraception, most pharmacists recommend backup contraception for women who use concomitant antibiotics.³ This practice could lead to poor compliance with the contraceptive regimen, the antibiotic regimen, or both.³

Simmons et al³ conducted a systematic review of randomized and nonrandomized studies that assessed pregnancy rates, breakthrough bleeding, ovulation suppression, and hormone pharmacokinetics in women taking oral or vaginal hormonal contraceptives in combination with nonrifamycin antibiotics, including oral, intramuscular, and intravenous forms. Oral contraceptives used in the studies included a range of doses and progestins, but lowest-dose pills, such as those containing less than 30 µg ethinyl estradiol or less than 150 µg levonorgestrel, were not included.

The contraceptive formulations in this systematic review³ included oral contraceptive pills, emergency contraception pills, and the contraceptive vaginal ring. The effect of antibiotics on other nonoral contraceptives, such as the transdermal patch, injectables, and progestin implants was not studied.

Four observational studies³ evaluated pregnancy rates or hormonal contraception failure with any antibiotic use. In 2 of these 4 studies, there was no difference in pregnancy rates in women who used oral contraceptives with and without nonrifamycin antibiotics. However, ethinyl estradiol was shown to have increased clearance when administered with dirithromycin (a macrolide).³ Twenty-five of the studies reported measures of contraceptive effectiveness (ovulation) and pharmacokinetic outcomes.

There were no observed differences in ovulation suppression or breakthrough bleeding in any study that combined hormonal contraceptives with an antibiotic. Furthermore, there was no significant decrease in progestin pharmacokinetic parameters during coadministration with an antibiotic.³ Study limitations included small sample sizes and the observational nature of the data.

How would you counsel this patient?

Available evidence suggests that nonrifamycin antibiotics do not diminish the effectiveness of the vaginal contraceptive ring or an oral hormonal contraceptive that contains at least 30 µg of ethinyl estradiol or 150 µg of levonorgestrel. Current guidelines do not recommend the use of additional backup contraception, regardless of hormonal contraception dose or formulation.⁴ Likewise, the most recent guidance for dental practitioners (ie, from 2012) no longer advises women to use additional contraceptive protection when taking nonrifamycin antibiotics.⁵

In our practice, we discuss the option of additional protection when prescribing formulations with lower estrogen doses (< 30 µg), not only because of the limitations of the available data, but also because of the high rates of unintended pregnancy with typical use of combined hormonal contraceptives (9% per year, unrelated to use of antibiotics).⁴ However, if our patient would rather not use additional barrier methods, she can be reassured that concomitant nonrifamycin antibiotic use is unlikely to affect contraceptive effectiveness.

 

 

HORMONE REPLACEMENT THERAPY IN CARRIERS OF THE BRCA1 MUTATION

A 41-year-old healthy mother of 3 was recently found to be a carrier of the BRCA1 mutation. She is planning to undergo prophylactic bilateral salpingo-oophorectomy for ovarian cancer prevention. However, she is apprehensive about undergoing surgical menopause. Should she be started on hormone replacement therapy after oophorectomy? How would hormone replacement therapy affect her risk of breast cancer?

In females who carry the BRCA1 mutation, the cumulative risk of both ovarian and breast cancer approaches 44% (95% confidence interval [CI] 36%–53%) and 72% (95% CI 65%–79%) by age 80.⁶ Prophylactic salpingo-oophorectomy reduces the risk of breast cancer by 50% and the risk of ovarian cancer by 90%. Unfortunately, premature withdrawal of ovarian hormones has been associated with long-term adverse effects including significant vasomotor symptoms, decreased quality of life, sexual dysfunction, early mortality, bone loss, decline in mood and cognition, and poor cardiovascular outcomes.⁷ Many of these effects can be avoided or lessened with hormone replacement therapy.

Kotsopoulos et al⁸ conducted a longitudinal, prospective analysis of BRCA1 mutation carriers in a multicenter study between 1995 and 2017. The mean follow-up period was 7.6 years (range 0.4–22.1). The study assessed associations between the use of hormone replacement therapy and breast cancer risk in carriers of the BRCA1 mutation who underwent prophylactic salpingo-oophorectomy. Study participants did not have a personal history of cancer. Those with a history of prophylactic mastectomy were excluded.

Participants completed a series of questionnaires every 2 years, disclosing updates in personal medical, cancer, and reproductive history. The questionnaires also inquired about the use of hormone replacement therapy, including the type used (estrogen only, progestin only, estrogen plus progestin, other), brand name, duration of use, and dose and route of administration (pill, patch, suppository).

Of the 13,087 BRCA1 mutation carriers identified, 872 met the study criteria. Of those, 377 (43%) reported using some form of hormone replacement therapy after salpingo-oophorectomy, and 495 (57%) did not. The average duration of use was 3.9 years (range 0.5–19), with most (69%) using estrogen alone; 18% used other regimens, including estrogen plus progestin and progestin only. A small percentage of participants did not indicate which formulation they used. On average, women using hormone replacement therapy underwent prophylactic oophorectomy earlier than nonusers (age 43.0 vs 48.4; absolute difference 5.5 years, P < .001).

During follow-up, there was no significant difference noted in the proportion of women diagnosed with breast cancer between hormone replacement therapy users and nonusers (10.3 vs 10.7%; absolute difference 0.4%; P = .86). In fact, for each year of estrogen-containing hormone replacement therapy, there was an 18% reduction in breast cancer risk when oophorectomy was performed before age 45 (95% CI 0.69–0.97). The authors also noted a nonsignificant 14% trend toward an increase in breast cancer risk for each year of progestin use after oophorectomy when surgery was performed before age 45 (95% CI 0.9–1.46).

Although prophylactic hysterectomy was not recommended, the authors noted that hysterectomy would eliminate the need for progestin-containing hormone replacement therapy. For those who underwent oophorectomy after age 45, hormone replacement therapy did not increase or decrease the risk of breast cancer.⁷

A meta-analysis by Marchetti et al⁹ also supports the safety of hormone replacement therapy after risk-reducing salpingo-oophorectomy. Three studies that included 1,100 patients were analyzed (including the Kotsopoulos study⁸ noted above). There was a nonsignificant decrease in breast cancer risk in women on estrogen-only hormone replacement therapy compared with women on estrogen-plus-progestin therapy (odds ratio 0.53, 95% CI 0.25–1.15). Overall, the authors regarded hormone replacement therapy as a safe therapeutic option after prophylactic salpingo-oophorectomy in carriers of the BRCA1 and BRCA2 mutations.⁹

In a case-control study published in 2016,¹⁰ hormone replacement therapy was assessed in 432 postmenopausal BRCA1 mutation carriers with invasive breast cancer (cases) and in 432 BRCA1 mutation carriers without a history of breast cancer (controls). Results showed no difference in breast cancer risk between hormone replacement therapy users and nonusers.¹⁰

Rebbeck et al¹¹ evaluated short-term hormone replacement therapy in BRCA1 and BRCA2 gene-mutation carriers after they underwent prophylactic salpingo-oophorectomy. The results showed that hormone replacement did not affect the breast cancer risk-reduction conferred with prophylactic bilateral salpingo-oophorectomy.

Johansen et al¹² evaluated hormone replacement therapy in premenopausal women after prophylactic salpingo-oophorectomy. They studied 324 carriers of BRCA gene mutations after they underwent prophylactic salpingo-oophorectomy and a subset of 950 controls who had bilateral salpingo-oophorectomy for reasons unrelated to cancer. In both groups, hormone replacement therapy was underutilized. The authors recommended using it when clinically indicated.

Should your patient start hormone replacement therapy?

This patient is healthy, and in the absence of contraindications, systemic hormone replacement therapy after prophylactic oophorectomy could mitigate the potential adverse effects of surgically induced menopause. The patient can be reassured that estrogen-containing short-term hormone replacement therapy is unlikely to increase her breast cancer risk.

 

 

HORMONAL CONTRACEPTION AND THE RISK OF BREAST CANCER

A 44-year-old woman presents to your office for an annual visit. She is sexually active but does not wish to become pregnant. She has a family history of breast cancer: her mother was diagnosed at age 53. She is interested in an oral contraceptive to prevent pregnancy and acne. However, she is nervous about being on any contraceptive that may increase her risk of breast cancer.

To date, studies assessing the effect of hormonal contraception on the risk of breast cancer have produced inconsistent results. Although most studies have shown no associated risk, a few have shown a temporary 20% to 30% increased risk of breast cancer during use.^13,14 Case-controlled studies that reported an association between hormonal contraception and breast cancer included populations taking higher-dose combination pills, which are no longer prescribed. Most studies do not evaluate specific formulations of hormonal contraception, and little is known about effects associated with intrauterine devices or progestin-only contraception.

A prospective study performed by Mørch et al¹³ followed more than 1 million reproductive-aged women for a mean of 10.9 years. The Danish Cancer Registry was used to identify cases of invasive breast cancer. Women who used hormonal contraceptives had a relative risk of breast cancer of 1.20 compared with women not on hormonal contraception (95% CI 1.14–1.26). The study suggested that those who had been on contraceptive agents for more than 5 years had an increased risk and that this risk remained for 5 years after the agents were discontinued. Conversely, no increased risk of cancer was noted in those who used hormonal contraception for less than 5 years. No notable differences were seen among various formulations.

For women using the levonorgestrel-containing intrauterine device, the relative risk of breast cancer was 1.21 (95% CI 1.11–1.33). A few cancers were noted in those who used the progestin-only implant or those using depot medroxyprogesterone acetate. While the study showed an increased relative risk of breast cancer, the absolute risk was low—13 cases per 100,000, or approximately 1 additional case of breast cancer per 7,690 per year.¹³

This study had several important limitations. The authors did not adjust for common breast cancer risk factors including age at menarche, alcohol use, or breastfeeding. Additionally, the study did not account for the use of hormonal contraception before the study period and conversely, did not account for women who may have stopped taking their contraceptive despite their prescribed duration. The frequency of mammography was not explicitly noted, which could have shifted results for women who had more aggressive screening.

It is also noteworthy that the use of high-dose systemic progestins was not associated with an increased risk, whereas the levonorgestrel intrauterine device, which contains only 1/20th the dose of a low-dose oral contraceptive pill, was associated with an increased risk. This discrepancy in risk warrants further investigation, and clinicians should be aware that this inconsistency needs validation before changing clinical practice.

In an observational cohort study,¹⁵ more than 100,000 women ages 50 to 71 were followed prospectively for 15 years to evaluate the association between hormonal contraceptive use and the risk of gynecologic and breast cancers. In this study, the duration of hormonal contraceptive use, smoking status, alcohol use, body mass index, physical activity, and family history of cancer were recorded. Long-term hormonal contraceptive use reduced ovarian and endometrial cancer risks by 40% and 34%, respectively, with no increase in breast cancer risk regardless of family history.

How would you counsel the patient?

The patient should be educated on the benefits of hormonal contraception that extend beyond pregnancy prevention, including regulation of menses, improved acne, decreased risk of endometrial and ovarian cancer, and likely reductions in colorectal cancer and overall mortality risk.^13–16 Further, after their own systematic review of the data assessing risk of breast cancer with hormonal contraception, the US Centers for Disease Control and Prevention state in their guidelines that all contraceptives may be used without limitation in those who have a family history of breast cancer.⁴ Any potential increased risk of breast cancer in women using hormonal contraception is small and would not outweigh the benefits associated with use.

One must consider the impact of an unintended pregnancy in such women, including effects on the health of the fetus and mother. Recent reports on the increasing rates of maternal death in the US (23.8 of 100,000 live births) serve as a reminder of the complications that can arise with pregnancy, especially if a mother’s health is not optimized before conception.¹⁷

 

 

MAMMOGRAPHY PLUS TOMOSYNTHESIS VS MAMMOGRAPHY ALONE

The same 44-year-old patient now inquires about screening for breast cancer. She is curious about 3-dimensional mammography and whether it would be a better screening test for her.

Digital breast tomosynthesis (DBT) is a newer imaging modality that provides a 3-dimensional reconstruction of the breast using low-dose x-ray imaging. Some studies have shown that combining DBT with digital mammography may be superior to digital mammography alone in detecting cancers.¹⁸ However, digital mammography is currently the gold standard for breast cancer screening and is the only test proven to reduce mortality.^18,19

In a retrospective US study of 13 medical centers,²⁰ breast cancer detection rates increased by 41% the year after DBT was introduced, from 2.9 to 4.1 per 1,000 cases. DBT was associated with 16 fewer patients recalled for repeat imaging out of 1,000 women screened (as opposed to mammography alone). Two European studies similarly suggested an increase in cancer detection with lower recall rates.^21,22

Is 3-D mammography a better option?

In a 2-arm study by Pattacini et al,¹⁸ nearly 20,000 women ages 45 to 70 were randomized to undergo either digital mammography or digital mammography plus DBT for primary breast cancer screening. Women were enrolled over a 2-year period and were followed for 4.5 years, and the development of a primary invasive cancer was the primary end point. Recall rates, reading times, and radiation doses were also compared between the 2 groups.

Overall, the cancer detection rate was higher in the digital mammography plus DBT arm compared with digital mammography alone (8.6 vs 4.5 per 1,000). The detection rates were higher in the combined screening group among all age subgroups, with relative risks ranging from 1.83 to 2.04 (P = .93). The recall rate was 3.5% in the 2 arms, with relative risks ranging from 0.93 to 1.11 (P = .52). There was a reduction in the number of false positives seen in women undergoing digital mammography plus DBT when compared with digital mammography alone, from 30 per 1,000 to 27 per 1,000.

Detection of ductal carcinoma in situ increased in the experimental arm (relative detection 2.80, 95% CI 1.01–7.65) compared with invasive cancers. Comparing radiation, the dose was 2.3 times higher in those who underwent digital mammography plus DBT. The average reading times for digital mammography alone were 20 to 85 seconds; adding DBT added 35 to 81 seconds.¹⁹

Should you advise 3-D mammography?

The patient should be educated on the benefits of both digital mammography alone and digital mammography plus DBT. The use of digital mammography plus DBT has been supported in various studies and has been shown to increase cancer detection rates, although data are still conflicting regarding recall rates.^19,20 More studies are needed to determine its effect on breast cancer morality.

Routine use of DBT in women with or without dense breast tissue has not been recommended by organizations such as the USPSTF and the American College of Obstetricians and Gynecologists.^23,24 While there is an increased dose of radiation, it still falls below the US Food and Drug Administration limits and should not be the sole barrier to use.

Keeping up with current evidence-based healthcare practices is key to providing good clinical care to patients. This review presents 5 vignettes that highlight key issues in women’s health: osteoporosis screening, hormonal contraceptive interactions with antibiotics, hormone replacement therapy in carriers of the BRCA1 gene mutation, risks associated with hormonal contraception, and breast cancer diagnosis using digital tomosynthesis in addition to digital mammography. Supporting articles, all published in 2017 and 2018, were selected from high-impact medical and women’s health journals.

OSTEOPOROSIS SCREENING FOR FRACTURE PREVENTION

A 60-year-old woman reports that her last menstrual period was 7 years ago. She has no history of falls or fractures, and she takes no medications. She smokes 10 cigarettes per day and drinks 3 to 4 alcoholic beverages on most days of the week. She is 5 feet 6 inches (170 cm) tall and weighs 107 lb. Should she be screened for osteoporosis?

Osteoporosis is underdiagnosed

It is estimated that, in the United States, 12.3 million individuals older than 50 will develop osteoporosis by 2020. Missed opportunities to screen high-risk individuals can lead to fractures, including fractures of the hip.¹

Updated screening recommendations

In 2018, the US Preventive Services Task Force (USPSTF) developed and published evidence-based recommendations for osteoporosis screening to help providers identify and treat osteoporosis early to prevent fractures.² Available evidence on screening and treatment in women and men were reviewed with the intention of updating the 2011 USPSTF recommendations. The review also evaluated risk assessment tools, screening intervals, and efficacy of screening and treatment in various subpopulations.

Since the 2011 recommendations, more data have become available on fracture risk assessment with or without bone mineral density measurements. In its 2018 report, the USPSTF recommends that postmenopausal women younger than 65 should undergo screening with a bone density test if their 10-year risk of major osteoporotic fracture is more than 8.4%. This is equivalent to the fracture risk of a 65-year-old white woman with no major risk factors for fracture (grade B recommendation—high certainty that the benefit is moderate, or moderate certainty that the benefit is moderate to substantial).²

Assessment of fracture risk

For postmenopausal women who are under age 65 and who have at least 1 risk factor for fracture, it is reasonable to use a clinical risk assessment tool to determine who should undergo screening with bone mineral density measurement. Risk factors associated with an increased risk of osteoporotic fractures include a parental history of hip fracture, smoking, intake of 3 or more alcoholic drinks per day, low body weight, malabsorption, rheumatoid arthritis, diabetes, and postmenopausal status (not using estrogen replacement). Medications should be carefully reviewed for those that can increase the risk of fractures, including steroids and antiestrogen treatments.

The 10-year risk of a major osteoporotic or hip fracture can be assessed using the Fractional Risk Assessment Tool (FRAX), available at www.sheffield.ac.uk/FRAX/. Other acceptable tools that perform similarly to FRAX include the Osteoporosis Risk Assessment Instrument (ORAI) (10 studies; N = 16,780), Osteoporosis Index of Risk (OSIRIS) (5 studies; N = 5,649), Osteoporosis Self-Assessment Tool (OST) (13 studies; N = 44,323), and Simple Calculated Osteoporosis Risk Estimation (SCORE) (8 studies; N = 15,362).

Should this patient be screened for osteoporosis?

Based on the FRAX, this patient’s 10-year risk of major osteoporosis fracture is 9.2%. She would benefit from osteoporosis screening with a bone density test.

DO ANTIBIOTICS REDUCE EFFECTIVENESS OF HORMONAL CONTRACEPTION?

A 27-year-old woman presents with a dog bite on her right hand and is started on oral antibiotics. She takes an oral contraceptive that contains 35 µg of ethinyl estradiol and 0.25 mg of norgestimate. She asks if she should use condoms while taking antibiotics.

The antibiotics rifampin and rifabutin are known inducers of the hepatic enzymes required for contraceptive steroid metabolism, whereas other antibiotics are not. Despite the lack of compelling evidence that broad-spectrum antibiotics interfere with the efficacy of hormonal contraception, most pharmacists recommend backup contraception for women who use concomitant antibiotics.³ This practice could lead to poor compliance with the contraceptive regimen, the antibiotic regimen, or both.³

Simmons et al³ conducted a systematic review of randomized and nonrandomized studies that assessed pregnancy rates, breakthrough bleeding, ovulation suppression, and hormone pharmacokinetics in women taking oral or vaginal hormonal contraceptives in combination with nonrifamycin antibiotics, including oral, intramuscular, and intravenous forms. Oral contraceptives used in the studies included a range of doses and progestins, but lowest-dose pills, such as those containing less than 30 µg ethinyl estradiol or less than 150 µg levonorgestrel, were not included.

The contraceptive formulations in this systematic review³ included oral contraceptive pills, emergency contraception pills, and the contraceptive vaginal ring. The effect of antibiotics on other nonoral contraceptives, such as the transdermal patch, injectables, and progestin implants was not studied.

Four observational studies³ evaluated pregnancy rates or hormonal contraception failure with any antibiotic use. In 2 of these 4 studies, there was no difference in pregnancy rates in women who used oral contraceptives with and without nonrifamycin antibiotics. However, ethinyl estradiol was shown to have increased clearance when administered with dirithromycin (a macrolide).³ Twenty-five of the studies reported measures of contraceptive effectiveness (ovulation) and pharmacokinetic outcomes.

There were no observed differences in ovulation suppression or breakthrough bleeding in any study that combined hormonal contraceptives with an antibiotic. Furthermore, there was no significant decrease in progestin pharmacokinetic parameters during coadministration with an antibiotic.³ Study limitations included small sample sizes and the observational nature of the data.

How would you counsel this patient?

Available evidence suggests that nonrifamycin antibiotics do not diminish the effectiveness of the vaginal contraceptive ring or an oral hormonal contraceptive that contains at least 30 µg of ethinyl estradiol or 150 µg of levonorgestrel. Current guidelines do not recommend the use of additional backup contraception, regardless of hormonal contraception dose or formulation.⁴ Likewise, the most recent guidance for dental practitioners (ie, from 2012) no longer advises women to use additional contraceptive protection when taking nonrifamycin antibiotics.⁵

In our practice, we discuss the option of additional protection when prescribing formulations with lower estrogen doses (< 30 µg), not only because of the limitations of the available data, but also because of the high rates of unintended pregnancy with typical use of combined hormonal contraceptives (9% per year, unrelated to use of antibiotics).⁴ However, if our patient would rather not use additional barrier methods, she can be reassured that concomitant nonrifamycin antibiotic use is unlikely to affect contraceptive effectiveness.

 

 

HORMONE REPLACEMENT THERAPY IN CARRIERS OF THE BRCA1 MUTATION

A 41-year-old healthy mother of 3 was recently found to be a carrier of the BRCA1 mutation. She is planning to undergo prophylactic bilateral salpingo-oophorectomy for ovarian cancer prevention. However, she is apprehensive about undergoing surgical menopause. Should she be started on hormone replacement therapy after oophorectomy? How would hormone replacement therapy affect her risk of breast cancer?

In females who carry the BRCA1 mutation, the cumulative risk of both ovarian and breast cancer approaches 44% (95% confidence interval [CI] 36%–53%) and 72% (95% CI 65%–79%) by age 80.⁶ Prophylactic salpingo-oophorectomy reduces the risk of breast cancer by 50% and the risk of ovarian cancer by 90%. Unfortunately, premature withdrawal of ovarian hormones has been associated with long-term adverse effects including significant vasomotor symptoms, decreased quality of life, sexual dysfunction, early mortality, bone loss, decline in mood and cognition, and poor cardiovascular outcomes.⁷ Many of these effects can be avoided or lessened with hormone replacement therapy.

Kotsopoulos et al⁸ conducted a longitudinal, prospective analysis of BRCA1 mutation carriers in a multicenter study between 1995 and 2017. The mean follow-up period was 7.6 years (range 0.4–22.1). The study assessed associations between the use of hormone replacement therapy and breast cancer risk in carriers of the BRCA1 mutation who underwent prophylactic salpingo-oophorectomy. Study participants did not have a personal history of cancer. Those with a history of prophylactic mastectomy were excluded.

Participants completed a series of questionnaires every 2 years, disclosing updates in personal medical, cancer, and reproductive history. The questionnaires also inquired about the use of hormone replacement therapy, including the type used (estrogen only, progestin only, estrogen plus progestin, other), brand name, duration of use, and dose and route of administration (pill, patch, suppository).

Of the 13,087 BRCA1 mutation carriers identified, 872 met the study criteria. Of those, 377 (43%) reported using some form of hormone replacement therapy after salpingo-oophorectomy, and 495 (57%) did not. The average duration of use was 3.9 years (range 0.5–19), with most (69%) using estrogen alone; 18% used other regimens, including estrogen plus progestin and progestin only. A small percentage of participants did not indicate which formulation they used. On average, women using hormone replacement therapy underwent prophylactic oophorectomy earlier than nonusers (age 43.0 vs 48.4; absolute difference 5.5 years, P < .001).

During follow-up, there was no significant difference noted in the proportion of women diagnosed with breast cancer between hormone replacement therapy users and nonusers (10.3 vs 10.7%; absolute difference 0.4%; P = .86). In fact, for each year of estrogen-containing hormone replacement therapy, there was an 18% reduction in breast cancer risk when oophorectomy was performed before age 45 (95% CI 0.69–0.97). The authors also noted a nonsignificant 14% trend toward an increase in breast cancer risk for each year of progestin use after oophorectomy when surgery was performed before age 45 (95% CI 0.9–1.46).

Although prophylactic hysterectomy was not recommended, the authors noted that hysterectomy would eliminate the need for progestin-containing hormone replacement therapy. For those who underwent oophorectomy after age 45, hormone replacement therapy did not increase or decrease the risk of breast cancer.⁷

A meta-analysis by Marchetti et al⁹ also supports the safety of hormone replacement therapy after risk-reducing salpingo-oophorectomy. Three studies that included 1,100 patients were analyzed (including the Kotsopoulos study⁸ noted above). There was a nonsignificant decrease in breast cancer risk in women on estrogen-only hormone replacement therapy compared with women on estrogen-plus-progestin therapy (odds ratio 0.53, 95% CI 0.25–1.15). Overall, the authors regarded hormone replacement therapy as a safe therapeutic option after prophylactic salpingo-oophorectomy in carriers of the BRCA1 and BRCA2 mutations.⁹

In a case-control study published in 2016,¹⁰ hormone replacement therapy was assessed in 432 postmenopausal BRCA1 mutation carriers with invasive breast cancer (cases) and in 432 BRCA1 mutation carriers without a history of breast cancer (controls). Results showed no difference in breast cancer risk between hormone replacement therapy users and nonusers.¹⁰

Rebbeck et al¹¹ evaluated short-term hormone replacement therapy in BRCA1 and BRCA2 gene-mutation carriers after they underwent prophylactic salpingo-oophorectomy. The results showed that hormone replacement did not affect the breast cancer risk-reduction conferred with prophylactic bilateral salpingo-oophorectomy.

Johansen et al¹² evaluated hormone replacement therapy in premenopausal women after prophylactic salpingo-oophorectomy. They studied 324 carriers of BRCA gene mutations after they underwent prophylactic salpingo-oophorectomy and a subset of 950 controls who had bilateral salpingo-oophorectomy for reasons unrelated to cancer. In both groups, hormone replacement therapy was underutilized. The authors recommended using it when clinically indicated.

Should your patient start hormone replacement therapy?

This patient is healthy, and in the absence of contraindications, systemic hormone replacement therapy after prophylactic oophorectomy could mitigate the potential adverse effects of surgically induced menopause. The patient can be reassured that estrogen-containing short-term hormone replacement therapy is unlikely to increase her breast cancer risk.

 

 

HORMONAL CONTRACEPTION AND THE RISK OF BREAST CANCER

A 44-year-old woman presents to your office for an annual visit. She is sexually active but does not wish to become pregnant. She has a family history of breast cancer: her mother was diagnosed at age 53. She is interested in an oral contraceptive to prevent pregnancy and acne. However, she is nervous about being on any contraceptive that may increase her risk of breast cancer.

To date, studies assessing the effect of hormonal contraception on the risk of breast cancer have produced inconsistent results. Although most studies have shown no associated risk, a few have shown a temporary 20% to 30% increased risk of breast cancer during use.^13,14 Case-controlled studies that reported an association between hormonal contraception and breast cancer included populations taking higher-dose combination pills, which are no longer prescribed. Most studies do not evaluate specific formulations of hormonal contraception, and little is known about effects associated with intrauterine devices or progestin-only contraception.

A prospective study performed by Mørch et al¹³ followed more than 1 million reproductive-aged women for a mean of 10.9 years. The Danish Cancer Registry was used to identify cases of invasive breast cancer. Women who used hormonal contraceptives had a relative risk of breast cancer of 1.20 compared with women not on hormonal contraception (95% CI 1.14–1.26). The study suggested that those who had been on contraceptive agents for more than 5 years had an increased risk and that this risk remained for 5 years after the agents were discontinued. Conversely, no increased risk of cancer was noted in those who used hormonal contraception for less than 5 years. No notable differences were seen among various formulations.

For women using the levonorgestrel-containing intrauterine device, the relative risk of breast cancer was 1.21 (95% CI 1.11–1.33). A few cancers were noted in those who used the progestin-only implant or those using depot medroxyprogesterone acetate. While the study showed an increased relative risk of breast cancer, the absolute risk was low—13 cases per 100,000, or approximately 1 additional case of breast cancer per 7,690 per year.¹³

This study had several important limitations. The authors did not adjust for common breast cancer risk factors including age at menarche, alcohol use, or breastfeeding. Additionally, the study did not account for the use of hormonal contraception before the study period and conversely, did not account for women who may have stopped taking their contraceptive despite their prescribed duration. The frequency of mammography was not explicitly noted, which could have shifted results for women who had more aggressive screening.

It is also noteworthy that the use of high-dose systemic progestins was not associated with an increased risk, whereas the levonorgestrel intrauterine device, which contains only 1/20th the dose of a low-dose oral contraceptive pill, was associated with an increased risk. This discrepancy in risk warrants further investigation, and clinicians should be aware that this inconsistency needs validation before changing clinical practice.

In an observational cohort study,¹⁵ more than 100,000 women ages 50 to 71 were followed prospectively for 15 years to evaluate the association between hormonal contraceptive use and the risk of gynecologic and breast cancers. In this study, the duration of hormonal contraceptive use, smoking status, alcohol use, body mass index, physical activity, and family history of cancer were recorded. Long-term hormonal contraceptive use reduced ovarian and endometrial cancer risks by 40% and 34%, respectively, with no increase in breast cancer risk regardless of family history.

How would you counsel the patient?

The patient should be educated on the benefits of hormonal contraception that extend beyond pregnancy prevention, including regulation of menses, improved acne, decreased risk of endometrial and ovarian cancer, and likely reductions in colorectal cancer and overall mortality risk.^13–16 Further, after their own systematic review of the data assessing risk of breast cancer with hormonal contraception, the US Centers for Disease Control and Prevention state in their guidelines that all contraceptives may be used without limitation in those who have a family history of breast cancer.⁴ Any potential increased risk of breast cancer in women using hormonal contraception is small and would not outweigh the benefits associated with use.

One must consider the impact of an unintended pregnancy in such women, including effects on the health of the fetus and mother. Recent reports on the increasing rates of maternal death in the US (23.8 of 100,000 live births) serve as a reminder of the complications that can arise with pregnancy, especially if a mother’s health is not optimized before conception.¹⁷

 

 

MAMMOGRAPHY PLUS TOMOSYNTHESIS VS MAMMOGRAPHY ALONE

The same 44-year-old patient now inquires about screening for breast cancer. She is curious about 3-dimensional mammography and whether it would be a better screening test for her.

Digital breast tomosynthesis (DBT) is a newer imaging modality that provides a 3-dimensional reconstruction of the breast using low-dose x-ray imaging. Some studies have shown that combining DBT with digital mammography may be superior to digital mammography alone in detecting cancers.¹⁸ However, digital mammography is currently the gold standard for breast cancer screening and is the only test proven to reduce mortality.^18,19

In a retrospective US study of 13 medical centers,²⁰ breast cancer detection rates increased by 41% the year after DBT was introduced, from 2.9 to 4.1 per 1,000 cases. DBT was associated with 16 fewer patients recalled for repeat imaging out of 1,000 women screened (as opposed to mammography alone). Two European studies similarly suggested an increase in cancer detection with lower recall rates.^21,22

Is 3-D mammography a better option?

In a 2-arm study by Pattacini et al,¹⁸ nearly 20,000 women ages 45 to 70 were randomized to undergo either digital mammography or digital mammography plus DBT for primary breast cancer screening. Women were enrolled over a 2-year period and were followed for 4.5 years, and the development of a primary invasive cancer was the primary end point. Recall rates, reading times, and radiation doses were also compared between the 2 groups.

Overall, the cancer detection rate was higher in the digital mammography plus DBT arm compared with digital mammography alone (8.6 vs 4.5 per 1,000). The detection rates were higher in the combined screening group among all age subgroups, with relative risks ranging from 1.83 to 2.04 (P = .93). The recall rate was 3.5% in the 2 arms, with relative risks ranging from 0.93 to 1.11 (P = .52). There was a reduction in the number of false positives seen in women undergoing digital mammography plus DBT when compared with digital mammography alone, from 30 per 1,000 to 27 per 1,000.

Detection of ductal carcinoma in situ increased in the experimental arm (relative detection 2.80, 95% CI 1.01–7.65) compared with invasive cancers. Comparing radiation, the dose was 2.3 times higher in those who underwent digital mammography plus DBT. The average reading times for digital mammography alone were 20 to 85 seconds; adding DBT added 35 to 81 seconds.¹⁹

Should you advise 3-D mammography?

The patient should be educated on the benefits of both digital mammography alone and digital mammography plus DBT. The use of digital mammography plus DBT has been supported in various studies and has been shown to increase cancer detection rates, although data are still conflicting regarding recall rates.^19,20 More studies are needed to determine its effect on breast cancer morality.

Routine use of DBT in women with or without dense breast tissue has not been recommended by organizations such as the USPSTF and the American College of Obstetricians and Gynecologists.^23,24 While there is an increased dose of radiation, it still falls below the US Food and Drug Administration limits and should not be the sole barrier to use.

Obstructive sleep apnea (OSA) is an independent risk factor for ischemic stroke and may also, infrequently, be a consequence of stroke. It is significantly underdiagnosed in the general population and is highly prevalent in patients who have had a stroke. Many patients likely had their stroke because of this chronic untreated condition.

This review focuses on OSA and its prevalence, consequences, and treatment in patients after a stroke.

DEFINING AND QUANTIFYING OSA

OSA is the most common type of sleep-disordered breathing.^1,2 It involves repeated narrowing or complete collapse of the upper airway despite ongoing respiratory effort.^3,4 Apneic episodes are terminated by arousals from hypoxemia or efforts to breathe.⁵ In contrast, central sleep apnea is characterized by a patent airway but lack of airflow due to absent respiratory effort.⁵

In OSA, the number of episodes of apnea (absent airflow) and hypopnea (reduced airflow) are added together and divided by hours of sleep to calculate the apnea-hypopnea index (AHI). OSA is diagnosed by either of the following^3,4:

• AHI of 5 or higher, with clinical symptoms related to OSA (described below)
• AHI of 15 or higher, regardless of symptoms.

The AHI also defines OSA severity, as follows³:

• Mild: AHI 5 to 15
• Moderate: AHI 15 to 30
• Severe: AHI greater than 30.

Diagnostic criteria (eg, definition of hypopnea, testing methods, and AHI thresholds) have varied over time, an important consideration when reviewing the literature.

OSA IS MORE COMMON THAN EXPECTED AFTER STROKE

In the most methodologically sound and generalizable study of this topic to date, the Wisconsin Sleep Cohort Study⁶ reported in 2013 that about 14% of men and 5% of women ages 30 to 70 have an AHI greater than 5 (using 4% desaturation to score hypopneic episodes) with daytime sleepiness. Other studies suggest that 80% to 90% of people with OSA are undiagnosed and untreated.^1,7

The prevalence of OSA in patients who have had a stroke is much higher, ranging from 30% to 96% depending on the study methods and population.^1,8–12 A 2010 meta-analysis¹¹ of 29 studies reported that 72% of patients who had a stroke had an AHI greater than 5, and 29% had severe OSA. In this analysis, 7% of those with sleep-disordered breathing had central sleep apnea; still, these data indicate that the prevalence of OSA in these patients is about 5 times higher than in the general population.

RISK FACTORS MAY DIFFER IN STROKE POPULATION

Several risk factors for OSA have been identified.

Obesity is one of the strongest risk factors, with increasing body mass index (BMI) associated with increased OSA prevalence.^4,6,13 However, obesity appears to be a less significant risk factor in patients who have had a stroke than in the general population. In the 2010 meta-analysis¹¹ of OSA after stroke, the average BMI was only 26.4 kg/m² (with obesity defined as a BMI > 30.0 kg/m²), and increasing BMI was not associated with increasing AHI.

Male sex and advanced age are also OSA risk factors.^4,5 They remain significant in patients after a stroke; about 65% of poststroke patients who have OSA are men, and the older the patient, the more likely the AHI is greater than 10.¹¹

Ethnicity and genetics may also play important roles in OSA risk, with roughly 25% of OSA prevalence estimated to have a genetic basis.^14,15 Some risk factors for OSA such as craniofacial shape, upper airway anatomy, upper airway muscle dysfunction, increased respiratory chemosensitivity, and poor arousal threshold during sleep are likely determined by genetics and ethnicity.^14,15 Compared with people of European origin, Asians have a similar prevalence of OSA, but at a much lower average BMI, suggesting that other factors are significant.¹⁴ Possible genetically determined anatomic risk factors have not been specifically studied in the poststroke population, but it can be assumed they remain relevant.

Several studies have tried to find an association between OSA and type, location, etiology, or pattern of stroke.^{10,11,16–19} Although some suggest links between cardioembolic stroke and OSA,^16,20 or thrombolysis and OSA,¹⁰ most have found no association between OSA and stroke features.^11,12,21,22

HOW DOES OSA INCREASE STROKE RISK?

Untreated severe OSA is associated with increased cardiovascular mortality,^21,22 and OSA is an independent risk factor for incident stroke.²³ A number of mechanisms may explain these relationships.

Intermittent hypoxemia and recurrent sympathetic arousals resulting from OSA are thought to lead to many of the comorbid conditions with which it is associated: hypertension, coronary artery disease, heart failure, arrhythmias, pulmonary hypertension, and stroke. Repetitive decreases in ventilation lead to oxygen desaturations that result in cycles of increased sympathetic outflow and eventual sustained nocturnal hypertension and daytime chronic hypertension.^1,5,9,13 Also implicated are various changes in vasodilator and vasoconstrictor substances due to endothelial dysfunction and inflammation, which are thought to play a role in the atherogenic and prothrombotic states induced by OSA.^1,5,13

Cerebral circulation is altered primarily by the changes in partial pressure of carbon dioxide (Pco₂). During apnea, the Pco₂ rises, causing vasodilation and increased blood flow. After the apnea resolves, there is hyperpnea with resultant decreased Pco₂, and vasoconstriction. In a patient who already has vascular disease, the enhanced vasoconstriction could lead to ischemia.^1,5

Changes in intrathoracic pressure result in distortion of cardiac architecture. When the patient tries to breathe against an occluded airway, the intrathoracic pressure becomes more and more negative, increasing preload and afterload. When this happens repeatedly every night for years, it leads to remodeling of the heart such as left and right ventricular hypertrophy, with reduced stroke volume, myocardial ischemia, and increased risk of arrhythmia.^1,5,13

Untreated OSA is believed to predispose patients to develop atrial fibrillation through sympathetic overactivity, vascular inflammation, heart rate variability, and cardiac remodeling.²⁴ As atrial fibrillation is a major risk factor for stroke, particularly cardioembolic stroke, it may be another pathway of increased stroke risk in OSA.^16,20,25

 

 

CLINICAL MANIFESTATIONS OF OSA NOT OBVIOUS AFTER STROKE

OSA typically causes both daytime symptoms (excessive sleepiness, poor concentration, morning headache, depressive symptoms) and nighttime signs and symptoms (snoring, choking, gasping, night sweats, insomnia, nocturia, witnessed episodes of apnea).^3,4,26 Unfortunately, because these are nonspecific, OSA is often underdiagnosed.^4,26

Identifying OSA after a stroke may be a particular challenge, as patients often do not report classic symptoms, and the typical picture of OSA may have less predictive validity in these patients.^1,27,28 Within the first 24 hours after a stroke, hypersomnia, snoring history, and age are not predictive of OSA.¹ Patients found to have OSA after a stroke frequently do not have the traditional symptoms (sleepiness, snoring) seen in usual OSA patients. And they have higher rates of OSA at a younger age than the usual OSA patients, so age is not a predictive risk factor. In addition, daytime sleepiness and obesity are often absent or less prominent.^1,9,27,28  Finally, typical OSA signs and symptoms may be attributed to the stroke itself or to comorbidities affecting the patient, lowering suspicion for OSA.

OSA MAY HINDER STROKE RECOVERY, WORSEN OUTCOMES

OSA, particularly when moderate to severe, is linked to pathophysiologic changes that can hinder recovery from a stroke.

Intermittent hypoxemia during sleep can worsen vascular damage of at-risk tissue: nocturnal hypoxemia correlates with white matter hyperintensities on magnetic resonance imaging, a marker of ischemic demyelination.²⁹ Oxidative stress and release of inflammatory mediators associated with intermittent hypoxemia may impair vascular blood flow to brain tissue attempting to repair itself.³⁰ In addition, sympathetic overactivity and Pco₂ fluctuations associated with OSA may impede cerebral circulation.

Taken together, such ongoing nocturnal insults can lead to clinical consequences during this vulnerable period.

A 1996 study³¹ of patients recovering from a stroke found that an oxygen desaturation index (number of times that the blood oxygen level drops below a certain threshold, as measured by overnight oximetry) of more than 10 per hour was associated with worse functional recovery at discharge and at 3 and 12 months after discharge. This study also noted an association between time spent with oxygen saturations below 90% and the rate of death at 1 year.

A 2003 study³² reported that patients with an AHI greater than 10 by polysomnography spent an average of 13 days longer on the rehabilitation service and had worse functional and cognitive status on discharge, even after controlling for multiple confounders. Several subsequent studies have confirmed these and similar findings.^8,33,34

OSA has also been linked to depression,³⁵ which is common after stroke and may worsen outcomes.³⁶ The interaction between OSA, depression, and poststroke outcomes warrants further study.

In the general population, OSA has been independently associated with increased risk of stroke or death from any cause.^21,22,37 These associations have also been reported in the poststroke population: a 2014 meta-analysis found that OSA increased the risk of a repeat stroke (relative risk [RR] 1.8, 95% confidence interval [CI] 1.2–2.6) and all-cause mortality (RR 1.69, 95% CI 1.4–2.1).³⁸

TESTING FOR OSA AFTER STROKE

Because of the high prevalence of OSA in patients who have had a stroke and the potential for worse outcomes associated with untreated OSA, there should be a low threshold for evaluating for OSA soon after stroke. Objective testing is required to qualify for therapy,  and the gold standard for diagnosis of OSA is formal polysomnography conducted in a sleep laboratory.^2–4 Unfortunately, polysomnography may be unacceptable to some patients, is costly, and is resource-intensive, particularly in an inpatient or rehabilitation setting.²⁸ Ideally, to optimize testing efficiency, patients should be screened for the likelihood of OSA before polysomnography is ordered.

Questionnaires can help determine the need for further testing

Questionnaires developed to assess OSA risk³⁹ include the following:

The Berlin questionnaire, developed in 1999, has 10 questions assessing daytime and nighttime signs and symptoms and presence of hypertension.

The STOP questionnaire, developed in 2008, assesses snoring, tiredness, observed apneic episodes, and elevated blood pressure.

The STOP-BANG questionnaire, published in 2010, includes the STOP questions plus BMI over 35 kg/m², age over 50, neck circumference over 41 cm, and male gender.

A 2017 meta-analysis³⁹ of 108 studies with nearly 50,000 people found that the STOP-BANG questionnaire performed best with regard to sensitivity and diagnostic odds ratio, but with poor specificity.

These screening tools and modified versions of them have also been evaluated in patients who have had a stroke.

In 2015, Boulos et al²⁸ found that the STOP-BAG (a version of STOP-BANG that excludes neck circumference) and the 4-variable (4V) questionnaire (sex, BMI, blood pressure, snoring) had moderate predictive value for OSA within 6 months after sroke.

In 2016, Katzan et al⁴⁰ found that the STOP-BAG2 (STOP-BAG criteria plus continuous variables for BMI and age) had a high sensitivity for polysomnographically diagnosed OSA within the first year after a stroke. The specificity was significantly better than the STOP-BANG or the STOP-BAG questionnaire, although it remained suboptimal at 60.5%.

In 2017, Sico et al⁴¹ developed and assessed the SLEEP Inventory (sex, left heart failure, Epworth Sleepiness Scale, enlarged neck, weight in pounds, insulin resistance or diabetes, and National Institutes of Health Stroke Scale) and found that it outperformed the Berlin and STOP-BANG questionnaires in the poststroke setting. The SLEEP Inventory had the best specificity and negative predictive value, and a slightly better ability to correctly classify patients as having OSA or not, classifying 80% of patients correctly.

These newer screening tools (eg, STOP-BAG, STOP-BAG2, SLEEP) can be used to identify with reasonable accuracy which patients need definitive testing after stroke.

Pulse oximetry is another possible screening tool          

Overnight pulse oximetry may also help screen for sleep apnea and stratify risk after a stroke. A 2012 study⁴² of overnight oximetry to screen patients before surgery found that the oxygen desaturation index was significantly associated with the AHI measured by polysomnography. However, oximetry testing cannot distinguish between OSA and central sleep apnea, so it is insufficient to diagnose OSA or qualify patients for therapy. Further study is needed to examine the ability of overnight pulse oximetry to screen or to stratify risk for OSA after stroke.

Polysomnography vs home testing

Polysomnography is the gold standard for diagnosing OSA. Benefits include technical support and trouble-shooting, determining relationships between OSA, body position, and sleep stage, and the ability to intervene with treatment.² However, polysomnography can be cumbersome, costly, and resource-intensive.

A home sleep apnea test, ie, an unattended, limited-channel sleep study, may be an acceptable alternative.^2–4,43,44 Home testing does not require a sleep technologist to be present during testing, uses fewer sensors, and is less expensive than overnight polysomnography, but its utility can be limited: it fails to accurately discriminate between episodes of OSA and central sleep apnea, there is potential for false-negative results, and it can underestimate sleep apnea burden because it does not measure sleep.²

Institutional resources and logistics may influence the choice of diagnostic modality. No data exist on outcomes from different diagnostic testing methods in poststroke patients. Further research is needed.

 

 

POSITIVE AIRWAY PRESSURE THERAPY: BENEFITS, CHALLENGES, ALTERNATIVES

The first-line treatment for OSA is positive airway pressure (PAP).³ For most patients, this is continuous PAP (CPAP) or autoadjusting PAP (APAP). In some instances, particularly for those who cannot tolerate CPAP or who have comorbid hypoventilation, bilevel PAP (BPAP) may be indicated. More advanced PAP therapies are unlikely to be used after stroke.

PAP therapy is associated with reduced daytime sleepiness, improved mood, normalization of sleep architecture, improved systemic and pulmonary artery blood pressure, reduced rates of atrial fibrillation after ablation, and improved insulin sensitivity.^45–49 Whether it reduces the risk of cardiovascular events, including stroke, remains controversial; most data suggest that it does not.^50,51 However, when adherence to PAP therapy is considered rather than intention to treat, treatment has been found to lead to improved cardiovascular outcomes.⁵²

Mixed evidence of benefits after stroke

Observational studies provide evidence that CPAP may help patients with OSA after stroke, although results are mixed.^53–58 The studies ranged in size from 14 to 105 patients, enrolled patients with mostly moderate to severe OSA, and followed patients from 10 days to 7 years. Adherence to therapy was generally good in the short term (50%–70%), but only  15% to 30% of patients remained adherent at 5 to 7 years. Variable outcomes were reported, with some studies finding improved symptoms in the near term and mixed evidence of cardiovascular benefit in the longer ones. However, as these studies lacked randomization, drawing definitive conclusions on CPAP efficacy is difficult.

Patients were enrolled in the index admission or when starting a rehabilitation service—generally 2 to 3 weeks after their stroke. No clear association was found between the timing of initiating PAP therapy and outcomes. All patients had ischemic strokes, but few details were provided regarding stroke location, size, and severity. Exclusion criteria included severe underlying cardiopulmonary disease, confusion, severe stroke with marked impairment, and inability to cooperate. Almost all patients had moderate to severe OSA, and patients with central sleep apnea were excluded.

The major outcomes examined were drop-out rates, PAP adherence, and neurologic improvement based on neurologic functional scales (National Institutes of Health Stroke Scale and Canadian Neurologic Scale). As expected, dropout rates were higher in patients randomized to CPAP (OR 1.83, 95% CI 1.05–3.21, P = .03), although overall adherence was better than anticipated, with mean CPAP use across trials of 4.5 hours per night (95% CI 3.97–5.08) and with about 50% to 60% of patients adhering to therapy for at least 4 hours nightly.

Improvement in neurologic outcomes favored CPAP (standard mean difference 0.54, 95% CI 0.026–1.05), although considerable heterogeneity was seen. Improved sleepiness outcomes were inconsistent. Major cardiovascular outcomes were reported in only 2 studies (using the same data set) and showed delayed time to the next cardiovascular event for those treated with CPAP but no difference in cardiovascular event-free survival.

PAP poses more challenges after stroke

The primary limitation to PAP therapy is poor acceptance and adherence to therapy.⁵⁹ High rates of refusal of therapy and difficulty complying with treatment have been noted in the poststroke population, although recent studies have reported better adherence rates. How rates of adherence play out in real-world settings, outside of the controlled environment of a research study, has yet to be determined.

In general, CPAP adherence is affected by claustrophobia, difficulty tolerating a mask, problems with pressure intolerance, irritating air leaks, nasal congestion, and naso-oral dryness. Many such barriers can be overcome with use of a properly fitted mask, an appropriate pressure setting, heated humidification, nasal sprays (eg, saline, inhaled steroids), and education, encouragement, and reassurance.

After a stroke, additional obstacles may impede the ability to use PAP therapy.⁶⁸ Facial paresis (hemi- or bifacial) may make fitting of the mask problematic. Paralysis or weakness of the extremities may limit the ability to adjust or remove a mask. Aphasia can impair communication and understanding of the need to use PAP therapy, and upper-airway problems related to stroke, including dysphagia, may lead to pressure intolerance or risk of aspiration. Finally, a lack of perceived benefit, particularly if the patient does not have daytime sleepiness, may limit motivation.

Consider alternatives

For patients unlikely to succeed with PAP therapy, there are alternatives. Surgery and oral appliances are not usually realistic options in the setting of recent stroke, but positional therapy, including the use of body positioners to prevent supine sleep, as well as elevating the head of the bed, may be of some benefit.^69,70 A nasopharyngeal airway stenting device (nasal trumpet) may also be tolerated by some patients.

A proposed algorithm for screening, diagnosing, and treating OSA in patients after stroke is presented in Figure 1.

Obstructive sleep apnea (OSA) is an independent risk factor for ischemic stroke and may also, infrequently, be a consequence of stroke. It is significantly underdiagnosed in the general population and is highly prevalent in patients who have had a stroke. Many patients likely had their stroke because of this chronic untreated condition.

This review focuses on OSA and its prevalence, consequences, and treatment in patients after a stroke.

DEFINING AND QUANTIFYING OSA

OSA is the most common type of sleep-disordered breathing.^1,2 It involves repeated narrowing or complete collapse of the upper airway despite ongoing respiratory effort.^3,4 Apneic episodes are terminated by arousals from hypoxemia or efforts to breathe.⁵ In contrast, central sleep apnea is characterized by a patent airway but lack of airflow due to absent respiratory effort.⁵

In OSA, the number of episodes of apnea (absent airflow) and hypopnea (reduced airflow) are added together and divided by hours of sleep to calculate the apnea-hypopnea index (AHI). OSA is diagnosed by either of the following^3,4:

• AHI of 5 or higher, with clinical symptoms related to OSA (described below)
• AHI of 15 or higher, regardless of symptoms.

The AHI also defines OSA severity, as follows³:

• Mild: AHI 5 to 15
• Moderate: AHI 15 to 30
• Severe: AHI greater than 30.

Diagnostic criteria (eg, definition of hypopnea, testing methods, and AHI thresholds) have varied over time, an important consideration when reviewing the literature.

OSA IS MORE COMMON THAN EXPECTED AFTER STROKE

In the most methodologically sound and generalizable study of this topic to date, the Wisconsin Sleep Cohort Study⁶ reported in 2013 that about 14% of men and 5% of women ages 30 to 70 have an AHI greater than 5 (using 4% desaturation to score hypopneic episodes) with daytime sleepiness. Other studies suggest that 80% to 90% of people with OSA are undiagnosed and untreated.^1,7

The prevalence of OSA in patients who have had a stroke is much higher, ranging from 30% to 96% depending on the study methods and population.^1,8–12 A 2010 meta-analysis¹¹ of 29 studies reported that 72% of patients who had a stroke had an AHI greater than 5, and 29% had severe OSA. In this analysis, 7% of those with sleep-disordered breathing had central sleep apnea; still, these data indicate that the prevalence of OSA in these patients is about 5 times higher than in the general population.

RISK FACTORS MAY DIFFER IN STROKE POPULATION

Several risk factors for OSA have been identified.

Obesity is one of the strongest risk factors, with increasing body mass index (BMI) associated with increased OSA prevalence.^4,6,13 However, obesity appears to be a less significant risk factor in patients who have had a stroke than in the general population. In the 2010 meta-analysis¹¹ of OSA after stroke, the average BMI was only 26.4 kg/m² (with obesity defined as a BMI > 30.0 kg/m²), and increasing BMI was not associated with increasing AHI.

Male sex and advanced age are also OSA risk factors.^4,5 They remain significant in patients after a stroke; about 65% of poststroke patients who have OSA are men, and the older the patient, the more likely the AHI is greater than 10.¹¹

Ethnicity and genetics may also play important roles in OSA risk, with roughly 25% of OSA prevalence estimated to have a genetic basis.^14,15 Some risk factors for OSA such as craniofacial shape, upper airway anatomy, upper airway muscle dysfunction, increased respiratory chemosensitivity, and poor arousal threshold during sleep are likely determined by genetics and ethnicity.^14,15 Compared with people of European origin, Asians have a similar prevalence of OSA, but at a much lower average BMI, suggesting that other factors are significant.¹⁴ Possible genetically determined anatomic risk factors have not been specifically studied in the poststroke population, but it can be assumed they remain relevant.

Several studies have tried to find an association between OSA and type, location, etiology, or pattern of stroke.^{10,11,16–19} Although some suggest links between cardioembolic stroke and OSA,^16,20 or thrombolysis and OSA,¹⁰ most have found no association between OSA and stroke features.^11,12,21,22

HOW DOES OSA INCREASE STROKE RISK?

Untreated severe OSA is associated with increased cardiovascular mortality,^21,22 and OSA is an independent risk factor for incident stroke.²³ A number of mechanisms may explain these relationships.

Intermittent hypoxemia and recurrent sympathetic arousals resulting from OSA are thought to lead to many of the comorbid conditions with which it is associated: hypertension, coronary artery disease, heart failure, arrhythmias, pulmonary hypertension, and stroke. Repetitive decreases in ventilation lead to oxygen desaturations that result in cycles of increased sympathetic outflow and eventual sustained nocturnal hypertension and daytime chronic hypertension.^1,5,9,13 Also implicated are various changes in vasodilator and vasoconstrictor substances due to endothelial dysfunction and inflammation, which are thought to play a role in the atherogenic and prothrombotic states induced by OSA.^1,5,13

Cerebral circulation is altered primarily by the changes in partial pressure of carbon dioxide (Pco₂). During apnea, the Pco₂ rises, causing vasodilation and increased blood flow. After the apnea resolves, there is hyperpnea with resultant decreased Pco₂, and vasoconstriction. In a patient who already has vascular disease, the enhanced vasoconstriction could lead to ischemia.^1,5

Changes in intrathoracic pressure result in distortion of cardiac architecture. When the patient tries to breathe against an occluded airway, the intrathoracic pressure becomes more and more negative, increasing preload and afterload. When this happens repeatedly every night for years, it leads to remodeling of the heart such as left and right ventricular hypertrophy, with reduced stroke volume, myocardial ischemia, and increased risk of arrhythmia.^1,5,13

Untreated OSA is believed to predispose patients to develop atrial fibrillation through sympathetic overactivity, vascular inflammation, heart rate variability, and cardiac remodeling.²⁴ As atrial fibrillation is a major risk factor for stroke, particularly cardioembolic stroke, it may be another pathway of increased stroke risk in OSA.^16,20,25

 

 

CLINICAL MANIFESTATIONS OF OSA NOT OBVIOUS AFTER STROKE

OSA typically causes both daytime symptoms (excessive sleepiness, poor concentration, morning headache, depressive symptoms) and nighttime signs and symptoms (snoring, choking, gasping, night sweats, insomnia, nocturia, witnessed episodes of apnea).^3,4,26 Unfortunately, because these are nonspecific, OSA is often underdiagnosed.^4,26

Identifying OSA after a stroke may be a particular challenge, as patients often do not report classic symptoms, and the typical picture of OSA may have less predictive validity in these patients.^1,27,28 Within the first 24 hours after a stroke, hypersomnia, snoring history, and age are not predictive of OSA.¹ Patients found to have OSA after a stroke frequently do not have the traditional symptoms (sleepiness, snoring) seen in usual OSA patients. And they have higher rates of OSA at a younger age than the usual OSA patients, so age is not a predictive risk factor. In addition, daytime sleepiness and obesity are often absent or less prominent.^1,9,27,28  Finally, typical OSA signs and symptoms may be attributed to the stroke itself or to comorbidities affecting the patient, lowering suspicion for OSA.

OSA MAY HINDER STROKE RECOVERY, WORSEN OUTCOMES

OSA, particularly when moderate to severe, is linked to pathophysiologic changes that can hinder recovery from a stroke.

Intermittent hypoxemia during sleep can worsen vascular damage of at-risk tissue: nocturnal hypoxemia correlates with white matter hyperintensities on magnetic resonance imaging, a marker of ischemic demyelination.²⁹ Oxidative stress and release of inflammatory mediators associated with intermittent hypoxemia may impair vascular blood flow to brain tissue attempting to repair itself.³⁰ In addition, sympathetic overactivity and Pco₂ fluctuations associated with OSA may impede cerebral circulation.

Taken together, such ongoing nocturnal insults can lead to clinical consequences during this vulnerable period.

A 1996 study³¹ of patients recovering from a stroke found that an oxygen desaturation index (number of times that the blood oxygen level drops below a certain threshold, as measured by overnight oximetry) of more than 10 per hour was associated with worse functional recovery at discharge and at 3 and 12 months after discharge. This study also noted an association between time spent with oxygen saturations below 90% and the rate of death at 1 year.

A 2003 study³² reported that patients with an AHI greater than 10 by polysomnography spent an average of 13 days longer on the rehabilitation service and had worse functional and cognitive status on discharge, even after controlling for multiple confounders. Several subsequent studies have confirmed these and similar findings.^8,33,34

OSA has also been linked to depression,³⁵ which is common after stroke and may worsen outcomes.³⁶ The interaction between OSA, depression, and poststroke outcomes warrants further study.

In the general population, OSA has been independently associated with increased risk of stroke or death from any cause.^21,22,37 These associations have also been reported in the poststroke population: a 2014 meta-analysis found that OSA increased the risk of a repeat stroke (relative risk [RR] 1.8, 95% confidence interval [CI] 1.2–2.6) and all-cause mortality (RR 1.69, 95% CI 1.4–2.1).³⁸

TESTING FOR OSA AFTER STROKE

Because of the high prevalence of OSA in patients who have had a stroke and the potential for worse outcomes associated with untreated OSA, there should be a low threshold for evaluating for OSA soon after stroke. Objective testing is required to qualify for therapy,  and the gold standard for diagnosis of OSA is formal polysomnography conducted in a sleep laboratory.^2–4 Unfortunately, polysomnography may be unacceptable to some patients, is costly, and is resource-intensive, particularly in an inpatient or rehabilitation setting.²⁸ Ideally, to optimize testing efficiency, patients should be screened for the likelihood of OSA before polysomnography is ordered.

Questionnaires can help determine the need for further testing

Questionnaires developed to assess OSA risk³⁹ include the following:

The Berlin questionnaire, developed in 1999, has 10 questions assessing daytime and nighttime signs and symptoms and presence of hypertension.

The STOP questionnaire, developed in 2008, assesses snoring, tiredness, observed apneic episodes, and elevated blood pressure.

The STOP-BANG questionnaire, published in 2010, includes the STOP questions plus BMI over 35 kg/m², age over 50, neck circumference over 41 cm, and male gender.

A 2017 meta-analysis³⁹ of 108 studies with nearly 50,000 people found that the STOP-BANG questionnaire performed best with regard to sensitivity and diagnostic odds ratio, but with poor specificity.

These screening tools and modified versions of them have also been evaluated in patients who have had a stroke.

In 2015, Boulos et al²⁸ found that the STOP-BAG (a version of STOP-BANG that excludes neck circumference) and the 4-variable (4V) questionnaire (sex, BMI, blood pressure, snoring) had moderate predictive value for OSA within 6 months after sroke.

In 2016, Katzan et al⁴⁰ found that the STOP-BAG2 (STOP-BAG criteria plus continuous variables for BMI and age) had a high sensitivity for polysomnographically diagnosed OSA within the first year after a stroke. The specificity was significantly better than the STOP-BANG or the STOP-BAG questionnaire, although it remained suboptimal at 60.5%.

In 2017, Sico et al⁴¹ developed and assessed the SLEEP Inventory (sex, left heart failure, Epworth Sleepiness Scale, enlarged neck, weight in pounds, insulin resistance or diabetes, and National Institutes of Health Stroke Scale) and found that it outperformed the Berlin and STOP-BANG questionnaires in the poststroke setting. The SLEEP Inventory had the best specificity and negative predictive value, and a slightly better ability to correctly classify patients as having OSA or not, classifying 80% of patients correctly.

These newer screening tools (eg, STOP-BAG, STOP-BAG2, SLEEP) can be used to identify with reasonable accuracy which patients need definitive testing after stroke.

Pulse oximetry is another possible screening tool          

Overnight pulse oximetry may also help screen for sleep apnea and stratify risk after a stroke. A 2012 study⁴² of overnight oximetry to screen patients before surgery found that the oxygen desaturation index was significantly associated with the AHI measured by polysomnography. However, oximetry testing cannot distinguish between OSA and central sleep apnea, so it is insufficient to diagnose OSA or qualify patients for therapy. Further study is needed to examine the ability of overnight pulse oximetry to screen or to stratify risk for OSA after stroke.

Polysomnography vs home testing

Polysomnography is the gold standard for diagnosing OSA. Benefits include technical support and trouble-shooting, determining relationships between OSA, body position, and sleep stage, and the ability to intervene with treatment.² However, polysomnography can be cumbersome, costly, and resource-intensive.

A home sleep apnea test, ie, an unattended, limited-channel sleep study, may be an acceptable alternative.^2–4,43,44 Home testing does not require a sleep technologist to be present during testing, uses fewer sensors, and is less expensive than overnight polysomnography, but its utility can be limited: it fails to accurately discriminate between episodes of OSA and central sleep apnea, there is potential for false-negative results, and it can underestimate sleep apnea burden because it does not measure sleep.²

Institutional resources and logistics may influence the choice of diagnostic modality. No data exist on outcomes from different diagnostic testing methods in poststroke patients. Further research is needed.

 

 

POSITIVE AIRWAY PRESSURE THERAPY: BENEFITS, CHALLENGES, ALTERNATIVES

The first-line treatment for OSA is positive airway pressure (PAP).³ For most patients, this is continuous PAP (CPAP) or autoadjusting PAP (APAP). In some instances, particularly for those who cannot tolerate CPAP or who have comorbid hypoventilation, bilevel PAP (BPAP) may be indicated. More advanced PAP therapies are unlikely to be used after stroke.

PAP therapy is associated with reduced daytime sleepiness, improved mood, normalization of sleep architecture, improved systemic and pulmonary artery blood pressure, reduced rates of atrial fibrillation after ablation, and improved insulin sensitivity.^45–49 Whether it reduces the risk of cardiovascular events, including stroke, remains controversial; most data suggest that it does not.^50,51 However, when adherence to PAP therapy is considered rather than intention to treat, treatment has been found to lead to improved cardiovascular outcomes.⁵²

Mixed evidence of benefits after stroke

Observational studies provide evidence that CPAP may help patients with OSA after stroke, although results are mixed.^53–58 The studies ranged in size from 14 to 105 patients, enrolled patients with mostly moderate to severe OSA, and followed patients from 10 days to 7 years. Adherence to therapy was generally good in the short term (50%–70%), but only  15% to 30% of patients remained adherent at 5 to 7 years. Variable outcomes were reported, with some studies finding improved symptoms in the near term and mixed evidence of cardiovascular benefit in the longer ones. However, as these studies lacked randomization, drawing definitive conclusions on CPAP efficacy is difficult.

Patients were enrolled in the index admission or when starting a rehabilitation service—generally 2 to 3 weeks after their stroke. No clear association was found between the timing of initiating PAP therapy and outcomes. All patients had ischemic strokes, but few details were provided regarding stroke location, size, and severity. Exclusion criteria included severe underlying cardiopulmonary disease, confusion, severe stroke with marked impairment, and inability to cooperate. Almost all patients had moderate to severe OSA, and patients with central sleep apnea were excluded.

The major outcomes examined were drop-out rates, PAP adherence, and neurologic improvement based on neurologic functional scales (National Institutes of Health Stroke Scale and Canadian Neurologic Scale). As expected, dropout rates were higher in patients randomized to CPAP (OR 1.83, 95% CI 1.05–3.21, P = .03), although overall adherence was better than anticipated, with mean CPAP use across trials of 4.5 hours per night (95% CI 3.97–5.08) and with about 50% to 60% of patients adhering to therapy for at least 4 hours nightly.

Improvement in neurologic outcomes favored CPAP (standard mean difference 0.54, 95% CI 0.026–1.05), although considerable heterogeneity was seen. Improved sleepiness outcomes were inconsistent. Major cardiovascular outcomes were reported in only 2 studies (using the same data set) and showed delayed time to the next cardiovascular event for those treated with CPAP but no difference in cardiovascular event-free survival.

PAP poses more challenges after stroke

The primary limitation to PAP therapy is poor acceptance and adherence to therapy.⁵⁹ High rates of refusal of therapy and difficulty complying with treatment have been noted in the poststroke population, although recent studies have reported better adherence rates. How rates of adherence play out in real-world settings, outside of the controlled environment of a research study, has yet to be determined.

In general, CPAP adherence is affected by claustrophobia, difficulty tolerating a mask, problems with pressure intolerance, irritating air leaks, nasal congestion, and naso-oral dryness. Many such barriers can be overcome with use of a properly fitted mask, an appropriate pressure setting, heated humidification, nasal sprays (eg, saline, inhaled steroids), and education, encouragement, and reassurance.

After a stroke, additional obstacles may impede the ability to use PAP therapy.⁶⁸ Facial paresis (hemi- or bifacial) may make fitting of the mask problematic. Paralysis or weakness of the extremities may limit the ability to adjust or remove a mask. Aphasia can impair communication and understanding of the need to use PAP therapy, and upper-airway problems related to stroke, including dysphagia, may lead to pressure intolerance or risk of aspiration. Finally, a lack of perceived benefit, particularly if the patient does not have daytime sleepiness, may limit motivation.

Consider alternatives

For patients unlikely to succeed with PAP therapy, there are alternatives. Surgery and oral appliances are not usually realistic options in the setting of recent stroke, but positional therapy, including the use of body positioners to prevent supine sleep, as well as elevating the head of the bed, may be of some benefit.^69,70 A nasopharyngeal airway stenting device (nasal trumpet) may also be tolerated by some patients.

A proposed algorithm for screening, diagnosing, and treating OSA in patients after stroke is presented in Figure 1.

Obstructive sleep apnea (OSA) is an independent risk factor for ischemic stroke and may also, infrequently, be a consequence of stroke. It is significantly underdiagnosed in the general population and is highly prevalent in patients who have had a stroke. Many patients likely had their stroke because of this chronic untreated condition.

This review focuses on OSA and its prevalence, consequences, and treatment in patients after a stroke.

DEFINING AND QUANTIFYING OSA

OSA is the most common type of sleep-disordered breathing.^1,2 It involves repeated narrowing or complete collapse of the upper airway despite ongoing respiratory effort.^3,4 Apneic episodes are terminated by arousals from hypoxemia or efforts to breathe.⁵ In contrast, central sleep apnea is characterized by a patent airway but lack of airflow due to absent respiratory effort.⁵

In OSA, the number of episodes of apnea (absent airflow) and hypopnea (reduced airflow) are added together and divided by hours of sleep to calculate the apnea-hypopnea index (AHI). OSA is diagnosed by either of the following^3,4:

• AHI of 5 or higher, with clinical symptoms related to OSA (described below)
• AHI of 15 or higher, regardless of symptoms.

The AHI also defines OSA severity, as follows³:

• Mild: AHI 5 to 15
• Moderate: AHI 15 to 30
• Severe: AHI greater than 30.

Diagnostic criteria (eg, definition of hypopnea, testing methods, and AHI thresholds) have varied over time, an important consideration when reviewing the literature.

OSA IS MORE COMMON THAN EXPECTED AFTER STROKE

In the most methodologically sound and generalizable study of this topic to date, the Wisconsin Sleep Cohort Study⁶ reported in 2013 that about 14% of men and 5% of women ages 30 to 70 have an AHI greater than 5 (using 4% desaturation to score hypopneic episodes) with daytime sleepiness. Other studies suggest that 80% to 90% of people with OSA are undiagnosed and untreated.^1,7

The prevalence of OSA in patients who have had a stroke is much higher, ranging from 30% to 96% depending on the study methods and population.^1,8–12 A 2010 meta-analysis¹¹ of 29 studies reported that 72% of patients who had a stroke had an AHI greater than 5, and 29% had severe OSA. In this analysis, 7% of those with sleep-disordered breathing had central sleep apnea; still, these data indicate that the prevalence of OSA in these patients is about 5 times higher than in the general population.

RISK FACTORS MAY DIFFER IN STROKE POPULATION

Several risk factors for OSA have been identified.

Obesity is one of the strongest risk factors, with increasing body mass index (BMI) associated with increased OSA prevalence.^4,6,13 However, obesity appears to be a less significant risk factor in patients who have had a stroke than in the general population. In the 2010 meta-analysis¹¹ of OSA after stroke, the average BMI was only 26.4 kg/m² (with obesity defined as a BMI > 30.0 kg/m²), and increasing BMI was not associated with increasing AHI.

Male sex and advanced age are also OSA risk factors.^4,5 They remain significant in patients after a stroke; about 65% of poststroke patients who have OSA are men, and the older the patient, the more likely the AHI is greater than 10.¹¹

Ethnicity and genetics may also play important roles in OSA risk, with roughly 25% of OSA prevalence estimated to have a genetic basis.^14,15 Some risk factors for OSA such as craniofacial shape, upper airway anatomy, upper airway muscle dysfunction, increased respiratory chemosensitivity, and poor arousal threshold during sleep are likely determined by genetics and ethnicity.^14,15 Compared with people of European origin, Asians have a similar prevalence of OSA, but at a much lower average BMI, suggesting that other factors are significant.¹⁴ Possible genetically determined anatomic risk factors have not been specifically studied in the poststroke population, but it can be assumed they remain relevant.

Several studies have tried to find an association between OSA and type, location, etiology, or pattern of stroke.^{10,11,16–19} Although some suggest links between cardioembolic stroke and OSA,^16,20 or thrombolysis and OSA,¹⁰ most have found no association between OSA and stroke features.^11,12,21,22

HOW DOES OSA INCREASE STROKE RISK?

Untreated severe OSA is associated with increased cardiovascular mortality,^21,22 and OSA is an independent risk factor for incident stroke.²³ A number of mechanisms may explain these relationships.

Intermittent hypoxemia and recurrent sympathetic arousals resulting from OSA are thought to lead to many of the comorbid conditions with which it is associated: hypertension, coronary artery disease, heart failure, arrhythmias, pulmonary hypertension, and stroke. Repetitive decreases in ventilation lead to oxygen desaturations that result in cycles of increased sympathetic outflow and eventual sustained nocturnal hypertension and daytime chronic hypertension.^1,5,9,13 Also implicated are various changes in vasodilator and vasoconstrictor substances due to endothelial dysfunction and inflammation, which are thought to play a role in the atherogenic and prothrombotic states induced by OSA.^1,5,13

Cerebral circulation is altered primarily by the changes in partial pressure of carbon dioxide (Pco₂). During apnea, the Pco₂ rises, causing vasodilation and increased blood flow. After the apnea resolves, there is hyperpnea with resultant decreased Pco₂, and vasoconstriction. In a patient who already has vascular disease, the enhanced vasoconstriction could lead to ischemia.^1,5

Changes in intrathoracic pressure result in distortion of cardiac architecture. When the patient tries to breathe against an occluded airway, the intrathoracic pressure becomes more and more negative, increasing preload and afterload. When this happens repeatedly every night for years, it leads to remodeling of the heart such as left and right ventricular hypertrophy, with reduced stroke volume, myocardial ischemia, and increased risk of arrhythmia.^1,5,13

Untreated OSA is believed to predispose patients to develop atrial fibrillation through sympathetic overactivity, vascular inflammation, heart rate variability, and cardiac remodeling.²⁴ As atrial fibrillation is a major risk factor for stroke, particularly cardioembolic stroke, it may be another pathway of increased stroke risk in OSA.^16,20,25

 

 

CLINICAL MANIFESTATIONS OF OSA NOT OBVIOUS AFTER STROKE

OSA typically causes both daytime symptoms (excessive sleepiness, poor concentration, morning headache, depressive symptoms) and nighttime signs and symptoms (snoring, choking, gasping, night sweats, insomnia, nocturia, witnessed episodes of apnea).^3,4,26 Unfortunately, because these are nonspecific, OSA is often underdiagnosed.^4,26

Identifying OSA after a stroke may be a particular challenge, as patients often do not report classic symptoms, and the typical picture of OSA may have less predictive validity in these patients.^1,27,28 Within the first 24 hours after a stroke, hypersomnia, snoring history, and age are not predictive of OSA.¹ Patients found to have OSA after a stroke frequently do not have the traditional symptoms (sleepiness, snoring) seen in usual OSA patients. And they have higher rates of OSA at a younger age than the usual OSA patients, so age is not a predictive risk factor. In addition, daytime sleepiness and obesity are often absent or less prominent.^1,9,27,28  Finally, typical OSA signs and symptoms may be attributed to the stroke itself or to comorbidities affecting the patient, lowering suspicion for OSA.

OSA MAY HINDER STROKE RECOVERY, WORSEN OUTCOMES

OSA, particularly when moderate to severe, is linked to pathophysiologic changes that can hinder recovery from a stroke.

Intermittent hypoxemia during sleep can worsen vascular damage of at-risk tissue: nocturnal hypoxemia correlates with white matter hyperintensities on magnetic resonance imaging, a marker of ischemic demyelination.²⁹ Oxidative stress and release of inflammatory mediators associated with intermittent hypoxemia may impair vascular blood flow to brain tissue attempting to repair itself.³⁰ In addition, sympathetic overactivity and Pco₂ fluctuations associated with OSA may impede cerebral circulation.

Taken together, such ongoing nocturnal insults can lead to clinical consequences during this vulnerable period.

A 1996 study³¹ of patients recovering from a stroke found that an oxygen desaturation index (number of times that the blood oxygen level drops below a certain threshold, as measured by overnight oximetry) of more than 10 per hour was associated with worse functional recovery at discharge and at 3 and 12 months after discharge. This study also noted an association between time spent with oxygen saturations below 90% and the rate of death at 1 year.

A 2003 study³² reported that patients with an AHI greater than 10 by polysomnography spent an average of 13 days longer on the rehabilitation service and had worse functional and cognitive status on discharge, even after controlling for multiple confounders. Several subsequent studies have confirmed these and similar findings.^8,33,34

OSA has also been linked to depression,³⁵ which is common after stroke and may worsen outcomes.³⁶ The interaction between OSA, depression, and poststroke outcomes warrants further study.

In the general population, OSA has been independently associated with increased risk of stroke or death from any cause.^21,22,37 These associations have also been reported in the poststroke population: a 2014 meta-analysis found that OSA increased the risk of a repeat stroke (relative risk [RR] 1.8, 95% confidence interval [CI] 1.2–2.6) and all-cause mortality (RR 1.69, 95% CI 1.4–2.1).³⁸

TESTING FOR OSA AFTER STROKE

Because of the high prevalence of OSA in patients who have had a stroke and the potential for worse outcomes associated with untreated OSA, there should be a low threshold for evaluating for OSA soon after stroke. Objective testing is required to qualify for therapy,  and the gold standard for diagnosis of OSA is formal polysomnography conducted in a sleep laboratory.^2–4 Unfortunately, polysomnography may be unacceptable to some patients, is costly, and is resource-intensive, particularly in an inpatient or rehabilitation setting.²⁸ Ideally, to optimize testing efficiency, patients should be screened for the likelihood of OSA before polysomnography is ordered.

Questionnaires can help determine the need for further testing

Questionnaires developed to assess OSA risk³⁹ include the following:

The Berlin questionnaire, developed in 1999, has 10 questions assessing daytime and nighttime signs and symptoms and presence of hypertension.

The STOP questionnaire, developed in 2008, assesses snoring, tiredness, observed apneic episodes, and elevated blood pressure.

The STOP-BANG questionnaire, published in 2010, includes the STOP questions plus BMI over 35 kg/m², age over 50, neck circumference over 41 cm, and male gender.

A 2017 meta-analysis³⁹ of 108 studies with nearly 50,000 people found that the STOP-BANG questionnaire performed best with regard to sensitivity and diagnostic odds ratio, but with poor specificity.

These screening tools and modified versions of them have also been evaluated in patients who have had a stroke.

In 2015, Boulos et al²⁸ found that the STOP-BAG (a version of STOP-BANG that excludes neck circumference) and the 4-variable (4V) questionnaire (sex, BMI, blood pressure, snoring) had moderate predictive value for OSA within 6 months after sroke.

In 2016, Katzan et al⁴⁰ found that the STOP-BAG2 (STOP-BAG criteria plus continuous variables for BMI and age) had a high sensitivity for polysomnographically diagnosed OSA within the first year after a stroke. The specificity was significantly better than the STOP-BANG or the STOP-BAG questionnaire, although it remained suboptimal at 60.5%.

In 2017, Sico et al⁴¹ developed and assessed the SLEEP Inventory (sex, left heart failure, Epworth Sleepiness Scale, enlarged neck, weight in pounds, insulin resistance or diabetes, and National Institutes of Health Stroke Scale) and found that it outperformed the Berlin and STOP-BANG questionnaires in the poststroke setting. The SLEEP Inventory had the best specificity and negative predictive value, and a slightly better ability to correctly classify patients as having OSA or not, classifying 80% of patients correctly.

These newer screening tools (eg, STOP-BAG, STOP-BAG2, SLEEP) can be used to identify with reasonable accuracy which patients need definitive testing after stroke.

Pulse oximetry is another possible screening tool          

Overnight pulse oximetry may also help screen for sleep apnea and stratify risk after a stroke. A 2012 study⁴² of overnight oximetry to screen patients before surgery found that the oxygen desaturation index was significantly associated with the AHI measured by polysomnography. However, oximetry testing cannot distinguish between OSA and central sleep apnea, so it is insufficient to diagnose OSA or qualify patients for therapy. Further study is needed to examine the ability of overnight pulse oximetry to screen or to stratify risk for OSA after stroke.

Polysomnography vs home testing

Polysomnography is the gold standard for diagnosing OSA. Benefits include technical support and trouble-shooting, determining relationships between OSA, body position, and sleep stage, and the ability to intervene with treatment.² However, polysomnography can be cumbersome, costly, and resource-intensive.

A home sleep apnea test, ie, an unattended, limited-channel sleep study, may be an acceptable alternative.^2–4,43,44 Home testing does not require a sleep technologist to be present during testing, uses fewer sensors, and is less expensive than overnight polysomnography, but its utility can be limited: it fails to accurately discriminate between episodes of OSA and central sleep apnea, there is potential for false-negative results, and it can underestimate sleep apnea burden because it does not measure sleep.²

Institutional resources and logistics may influence the choice of diagnostic modality. No data exist on outcomes from different diagnostic testing methods in poststroke patients. Further research is needed.

 

 

POSITIVE AIRWAY PRESSURE THERAPY: BENEFITS, CHALLENGES, ALTERNATIVES

The first-line treatment for OSA is positive airway pressure (PAP).³ For most patients, this is continuous PAP (CPAP) or autoadjusting PAP (APAP). In some instances, particularly for those who cannot tolerate CPAP or who have comorbid hypoventilation, bilevel PAP (BPAP) may be indicated. More advanced PAP therapies are unlikely to be used after stroke.

PAP therapy is associated with reduced daytime sleepiness, improved mood, normalization of sleep architecture, improved systemic and pulmonary artery blood pressure, reduced rates of atrial fibrillation after ablation, and improved insulin sensitivity.^45–49 Whether it reduces the risk of cardiovascular events, including stroke, remains controversial; most data suggest that it does not.^50,51 However, when adherence to PAP therapy is considered rather than intention to treat, treatment has been found to lead to improved cardiovascular outcomes.⁵²

Mixed evidence of benefits after stroke

Observational studies provide evidence that CPAP may help patients with OSA after stroke, although results are mixed.^53–58 The studies ranged in size from 14 to 105 patients, enrolled patients with mostly moderate to severe OSA, and followed patients from 10 days to 7 years. Adherence to therapy was generally good in the short term (50%–70%), but only  15% to 30% of patients remained adherent at 5 to 7 years. Variable outcomes were reported, with some studies finding improved symptoms in the near term and mixed evidence of cardiovascular benefit in the longer ones. However, as these studies lacked randomization, drawing definitive conclusions on CPAP efficacy is difficult.

Patients were enrolled in the index admission or when starting a rehabilitation service—generally 2 to 3 weeks after their stroke. No clear association was found between the timing of initiating PAP therapy and outcomes. All patients had ischemic strokes, but few details were provided regarding stroke location, size, and severity. Exclusion criteria included severe underlying cardiopulmonary disease, confusion, severe stroke with marked impairment, and inability to cooperate. Almost all patients had moderate to severe OSA, and patients with central sleep apnea were excluded.

The major outcomes examined were drop-out rates, PAP adherence, and neurologic improvement based on neurologic functional scales (National Institutes of Health Stroke Scale and Canadian Neurologic Scale). As expected, dropout rates were higher in patients randomized to CPAP (OR 1.83, 95% CI 1.05–3.21, P = .03), although overall adherence was better than anticipated, with mean CPAP use across trials of 4.5 hours per night (95% CI 3.97–5.08) and with about 50% to 60% of patients adhering to therapy for at least 4 hours nightly.

Improvement in neurologic outcomes favored CPAP (standard mean difference 0.54, 95% CI 0.026–1.05), although considerable heterogeneity was seen. Improved sleepiness outcomes were inconsistent. Major cardiovascular outcomes were reported in only 2 studies (using the same data set) and showed delayed time to the next cardiovascular event for those treated with CPAP but no difference in cardiovascular event-free survival.

PAP poses more challenges after stroke

The primary limitation to PAP therapy is poor acceptance and adherence to therapy.⁵⁹ High rates of refusal of therapy and difficulty complying with treatment have been noted in the poststroke population, although recent studies have reported better adherence rates. How rates of adherence play out in real-world settings, outside of the controlled environment of a research study, has yet to be determined.

In general, CPAP adherence is affected by claustrophobia, difficulty tolerating a mask, problems with pressure intolerance, irritating air leaks, nasal congestion, and naso-oral dryness. Many such barriers can be overcome with use of a properly fitted mask, an appropriate pressure setting, heated humidification, nasal sprays (eg, saline, inhaled steroids), and education, encouragement, and reassurance.

After a stroke, additional obstacles may impede the ability to use PAP therapy.⁶⁸ Facial paresis (hemi- or bifacial) may make fitting of the mask problematic. Paralysis or weakness of the extremities may limit the ability to adjust or remove a mask. Aphasia can impair communication and understanding of the need to use PAP therapy, and upper-airway problems related to stroke, including dysphagia, may lead to pressure intolerance or risk of aspiration. Finally, a lack of perceived benefit, particularly if the patient does not have daytime sleepiness, may limit motivation.

Consider alternatives

For patients unlikely to succeed with PAP therapy, there are alternatives. Surgery and oral appliances are not usually realistic options in the setting of recent stroke, but positional therapy, including the use of body positioners to prevent supine sleep, as well as elevating the head of the bed, may be of some benefit.^69,70 A nasopharyngeal airway stenting device (nasal trumpet) may also be tolerated by some patients.

A proposed algorithm for screening, diagnosing, and treating OSA in patients after stroke is presented in Figure 1.

Should clinicians abandon the activated partial thromboplastin time (aPTT) for monitoring heparin therapy in favor of tests that measure the activity of the patient’s plasma against activated factor X (anti-Xa assays)?

Although other anticoagulants are now available for preventing and treating arterial and venous thromboembolism, unfractionated heparin—which requires laboratory monitoring of therapy—is still widely used. And this monitoring can be challenging. Despite its wide use, the aPTT lacks standardization, and the role of alternative monitoring assays such as the anti-Xa assay is not well defined.

This article reviews the advantages, limitations, and clinical applicability of anti-Xa assays for monitoring therapy with unfractionated heparin and other anticoagulants.

UNFRACTIONATED HEPARIN AND WARFARIN ARE STILL WIDELY USED

Until the mid-1990s, unfractionated heparin and oral vitamin K antagonists (eg, warfarin) were the only anticoagulants widely available for clinical use. These agents have complex pharmacokinetic and pharmacodynamic properties, resulting in highly variable dosing requirements (both between patients and in individual patients) and narrow therapeutic windows, making frequent laboratory monitoring and dose adjustments mandatory.

Over the past 3 decades, other anticoagulants have been approved, including low-molecular-weight heparins, fondaparinux, parenteral direct thrombin inhibitors, and direct oral anticoagulants. While these agents have expanded the options for preventing and treating thromboembolism, unfractionated heparin and warfarin are still the most appropriate choices for many patients, eg, those with stage 4 chronic kidney disease and end-stage renal disease on dialysis, and those with mechanical heart valves.

In addition, unfractionated heparin remains the anticoagulant of choice during procedures such as hemodialysis, percutaneous transluminal angioplasty, and cardiopulmonary bypass, as well as in hospitalized and critically ill patients, who often have acute kidney injury or require frequent interruptions of therapy for invasive procedures. In these scenarios, unfractionated heparin is typically preferred because of its short plasma half-life, complete reversibility by protamine, safety regardless of renal function, and low cost compared with parenteral direct thrombin inhibitors.

As long as unfractionated heparin and warfarin remain important therapies, the need for their laboratory monitoring continues. For warfarin monitoring, the prothrombin time and international normalized ratio are validated and widely reproducible methods. But monitoring unfractionated heparin therapy remains a challenge.

UNFRACTIONATED HEPARIN’S EFFECT IS UNPREDICTABLE

Unfractionated heparin, a negatively charged mucopolysaccharide, inhibits coagulation by binding to antithrombin through the high-affinity pentasaccharide sequence.^1–6 Such binding induces a conformational change in the antithrombin molecule, converting it to a rapid inhibitor of several coagulation proteins, especially factors IIa and Xa.^2–4

Unfractionated heparin inhibits factors IIa and Xa in a 1:1 ratio, but low-molecular-weight heparins inhibit factor Xa more than factor IIa, with IIa-Xa inhibition ratios ranging from 1:2 to 1:4, owing to their smaller molecular size.⁷

One of the most important reasons for the unpredictable and highly variable individual responses to unfractionated heparin is that, infused into the blood, the large and negatively charged unfractionated heparin molecules bind nonspecifically to positively charged plasma proteins.⁷ In patients who are critically ill, have acute infections or inflammatory states, or have undergone major surgery, unfractionated heparin binds to acute-phase proteins that are elevated, particularly factor VIII. This results in fewer free heparin molecules and a variable anticoagulant effect.⁸

In contrast, low-molecular-weight heparins have longer half-lives and bind less to plasma proteins, resulting in more predictable plasma levels following subcutaneous injection.⁹

 

 

MONITORING UNFRACTIONATED HEPARIN IMPROVES OUTCOMES

In 1960, Barritt and Jordan¹⁰ conducted a small but landmark trial that established the clinical importance of unfractionated heparin for treating venous thromboembolism. None of the patients who received unfractionated heparin for acute pulmonary embolism developed a recurrence during the subsequent 2 weeks, while 50% of those who did not receive it had recurrent pulmonary embolism, fatal in half of the cases.

The importance of achieving a specific aPTT therapeutic target was not demonstrated until a 1972 study by Basu et al,¹¹ in which 162 patients with venous thromboembolism were treated with heparin with a target aPTT of 1.5 to 2.5 times the control value. Patients who suffered recurrent events had subtherapeutic aPTT values on 71% of treatment days, while the rest of the patients, with no recurrences, had subtherapeutic aPTT values only 28% of treatment days. The different outcomes could not be explained by the average daily dose of unfractionated heparin, which was similar in the patients regardless of recurrence.

Subsequent studies showed that the best outcomes occur when unfractionated heparin is given in doses high enough to rapidly achieve a therapeutic prolongation of the aPTT,^12–14 and that the total daily dose is also important in preventing recurrences.^15,16 Failure to achieve a target aPTT within 24 hours of starting unfractionated heparin is associated with increased risk of recurrent venous thromboembolism.^13,17

Raschke et al¹⁷ found that patients prospectively randomized to weight-based doses of intravenous unfractionated heparin (bolus plus infusion) achieved significantly higher rates of therapeutic aPTT within 6 hours and 24 hours after starting the infusion, and had significantly lower rates of recurrent venous thromboembolism than those randomized to a fixed unfractionated heparin protocol, without an increase in major bleeding.

Smith et al,¹⁸ in a study of 400 consecutive patients with acute pulmonary embolism treated with unfractionated heparin, found that patients who achieved a therapeutic aPTT within 24 hours had lower in-hospital and 30-day mortality rates than those who did not achieve the first therapeutic aPTT until more than 24 hours after starting unfractionated heparin infusion.

Such data lend support to the widely accepted practice and current guideline recommendation⁸ of using laboratory assays to adjust the dose of unfractionated heparin to achieve and maintain a therapeutic target. The use of dosing nomograms significantly reduces the time to achieve a therapeutic aPTT while minimizing subtherapeutic and supratherapeutic unfractionated heparin levels.^19,20

THE aPTT REFLECTS THROMBIN INHIBITION

The aPTT has a log-linear relationship with plasma concentrations of unfractionated heparin,²¹ but it was not developed specifically for monitoring unfractionated heparin therapy. Originally described in 1953 as a screening tool for hemophilia,^22–24 the aPTT is prolonged in the setting of factor deficiencies (typically with levels < 45%, except for factors VII and XIII), as well as lupus anticoagulants and therapy with parenteral direct thrombin inhibitors.^8,25,26

Because thrombin (factor IIa) is 10 times more sensitive than factor Xa to inhibition by the heparin-antithrombin complex,^4,7 thrombin inhibition appears to be the most likely mechanism by which unfractionated heparin prolongs the aPTT. In contrast, aPTT is minimally or not at all prolonged by low-molecular-weight heparins, which are predominantly factor Xa inhibitors.⁷

HEPARIN ASSAYS MEASURE UNFRACTIONATED HEPARIN ACTIVITY

While the aPTT is a surrogate marker of unfractionated heparin activity in plasma, unfractionated heparin activity can be measured more precisely by so-called heparin assays, which are typically not direct measures of the plasma concentration of heparins, but rather functional assays that provide indirect estimates. They include protamine sulfate titration assays and anti-Xa assays.

Protamine sulfate titration assays measure the amount of protamine sulfate required to neutralize heparin: the more protamine required, the greater the estimated concentration of unfractionated heparin in plasma.^8,27–29 Protamine titration assays are technically demanding, so they are rarely used clinically.

Anti-Xa assays provide a measure of the functional level of heparins in plasma.^29–33 Chromogenic anti-Xa assays are available on automated analyzers with standardized kits^29,33,34 and may be faster to perform than the aPTT.³⁵

Experiments in rabbits show that unfractionated heparin inhibits thrombus formation and extension at concentrations of 0.2 to 0.4 U/mL as measured by the protamine titration assay,²⁷ which correlated with an anti-Xa activity of 0.35 to 0.67 U/mL in a randomized controlled trial.³²

Assays that directly measure the plasma concentration of heparin exist but are not clinically relevant because they also measure heparin molecules lacking the pentasaccharide sequence, which have no anticoagulant activity.³⁶

 

 

ANTI-Xa ASSAY VS THE aPTT

Anti-Xa assays are more expensive than the aPTT and are not available in all hospitals. For these reasons, the aPTT remains the most commonly used laboratory assay for monitoring unfractionated heparin therapy.

However, the aPTT correlates poorly with the activity level of unfractionated heparin in plasma. In one study, an anti-Xa level of 0.3 U/mL corresponded to aPTT results ranging from 47 to 108 seconds.³¹ Furthermore, in studies that used a heparin therapeutic target based on an aPTT ratio 1.5 to 2.5 times the control aPTT value, the lower end of that target range was often associated with subtherapeutic plasma unfractionated heparin activity measured by anti-Xa and protamine titration assays.^28,31

Because of these limitations, individual laboratories should determine their own aPTT therapeutic target ranges for unfractionated heparin based on the response curves obtained with the reagent and coagulometer used. The optimal therapeutic aPTT range for treating acute venous thromboembolism should be defined as the aPTT range (in seconds) that correlates with a plasma activity level of unfractionated heparin of 0.3 to 0.7 U/mL based on a chromogenic anti-Xa assay, or 0.2 to 0.4 U/mL based on a protamine titration assay.^32,34–36

Nevertheless, the anticoagulant effect of unfractionated heparin as measured by the aPTT can be unpredictable and can vary widely among individuals and in the same patient.⁷ This wide variability can be explained by a number of technical and biologic variables. Different commercial aPTT reagents, different lots of the same reagent, and different reagent and instrument combinations have different sensitivities to unfractionated heparin, which can lead to variable aPTT results.³⁷ Moreover, high plasma levels of acute-phase proteins, low plasma antithrombin levels, consumptive coagulopathies, liver failure, and lupus anticoagulants may also affect the aPTT.^{7,25,32,36–41} These variables account for the poor correlation—ranging from 25% to 66%—reported between aPTT and anti-Xa assays.^32,42–48

Such discrepancies may have serious clinical implications: if a patient’s aPTT is low (subtherapeutic) or high (supratherapeutic) but the anti-Xa assay result is within the therapeutic range (0.3–0.7 units/mL), changing the dose of unfractionated heparin (guided by an aPTT nomogram) may increase the risk of bleeding or of recurrent thromboembolism.

CLINICAL APPLICABILITY OF THE ANTI-Xa ASSAY

Neither anti-Xa nor protamine titration assays are standardized across reference laboratories, but chromogenic anti-Xa assays have better interlaboratory correlation than the aPTT^49,50 and can be calibrated specifically for unfractionated or low-molecular-weight heparins.^29,33

Although reagent costs are higher for chromogenic anti-Xa assays than for the aPTT, some technical variables (described below) may partially offset the cost difference.^29,33,41 In addition, unlike the aPTT, anti-Xa assays do not need local calibration; the therapeutic range for unfractionated heparin is the same (0.3–0.7 U/mL) regardless of instrument or reagent.^33,41

Most important, studies have found that patients monitored by anti-Xa assay achieve significantly higher rates of therapeutic anticoagulation within 24 and 48 hours after starting unfractionated heparin infusion than those monitored by the aPTT. Fewer dose adjustments and repeat tests are required, which may also result in lower cost.^32,51–55

While these studies found chromogenic anti-Xa assays better for achieving laboratory end points, data regarding relevant clinical outcomes are more limited. In a retrospective, observational cohort study,⁵¹ the rate of venous thromboembolism or bleeding-related death was 2% in patients receiving unfractionated heparin therapy monitored by anti-Xa assay and 6% in patients monitored by aPTT (P = .62). Rates of major hemorrhage were also not significantly different.

In a randomized controlled trial³² in 131 patients with acute venous thromboembolism and heparin resistance, rates of recurrent venous thromboembolism were 4.6% and 6.1% in the groups randomized to anti-Xa and aPTT monitoring, respectively, whereas overall bleeding rates were 1.5% and 6.1%, respectively. Again, the differences were not statistically significant.

Heparin resistance. Some patients require unusually high doses of unfractionated heparin to achieve a therapeutic aPTT: typically, more than 35,000 U over 24 hours,^7,8,32 or total daily doses that exceed their estimated weight-based requirements. Heparin resistance has been observed in various clinical settings.^{7,8,32,37–40,59–61} Patients with heparin resistance monitored by anti-Xa had similar rates of recurrent venous thromboembolism while receiving significantly lower doses of unfractionated heparin than those monitored by the aPTT.³²

Lupus anticoagulant. Patients with the specific antiphospholipid antibody known as lupus anticoagulant frequently have a prolonged baseline aPTT,²⁵ making it an unreliable marker of anticoagulant effect for intravenous unfractionated heparin therapy.

Critically ill infants and children. Arachchillage et al³⁵ found that infants (< 1 year old) treated with intravenous unfractionated heparin in an intensive care department had only a 32.4% correlation between aPTT and anti-Xa levels, which was lower than that found in children ages 1 to 15 (66%) and adults (52%). In two-thirds of cases of discordant aPTT and anti-Xa levels, the aPTT was elevated (supratherapeutic) while the anti-Xa assay was within the therapeutic range (0.3–0.7 U/mL). Despite the lack of data on clinical outcomes (eg, rates of thrombosis and bleeding) with the use of an anti-Xa assay, it has been considered the method of choice for unfractionated heparin monitoring in critically ill children, and especially in those under age 1.^{41,44,62–64}

While anti-Xa assays may also be better for unfractionated heparin monitoring in critically ill adults, the lack of clinical outcome data from large-scale randomized trials has precluded evidence-based recommendations favoring them over the aPTT.^8,34

 

 

LIMITATIONS OF ANTI-Xa ASSAYS

Anti-Xa assays are hampered by some technical limitations:

Samples must be processed within 1 hour to avoid heparin neutralization.³⁴

Samples must be clear. Hemolyzed or opaque samples (eg, due to bilirubin levels > 6.6 mg/dL or triglyceride levels > 360 mg/dL) cannot be processed, as they can cause falsely low levels.

Exposure to other anticoagulants can interfere with the results. The anti-Xa assay may be unreliable for unfractionated heparin monitoring in patients who are transitioned from low-molecular-weight heparins, fondaparinux, or an oral factor Xa inhibitor (apixaban, betrixaban, edoxaban, rivaroxaban) to intravenous unfractionated heparin, eg, due to hospitalization or acute kidney injury.^65,66 Different reports have found that anti-Xa assays may be elevated for as long as 63 to 96 hours after the last dose of oral Xa inhibitors,^67–69 potentially resulting in underdosing of unfractionated heparin. In such settings, unfractionated heparin therapy should be monitored by the aPTT.

ANTI-Xa ASSAYS AND LOW-MOLECULAR-WEIGHT HEPARINS

Most patients receiving low-molecular-weight heparins do not need laboratory monitoring.⁸ Alhenc-Gelas et al⁷⁰ randomized patients to receive dalteparin in doses either based on weight or guided by anti-Xa assay results, and found that dose adjustments were rare and lacked clinical benefit.

The suggested therapeutic anti-Xa levels for low-molecular-weight heparins are:

• 0.5–1.2 U/mL for twice-daily enoxaparin
• 1.0–2.0 U/mL for once-daily enoxaparin or dalteparin.

Levels should be measured at peak plasma level (ie, 3–4 hours after subcutaneous injection, except during pregnancy, when it is 4–6 hours), and only after at least 3 doses of low-molecular-weight heparin.^8,71 Unlike the anti-Xa therapeutic range recommended for unfractionated heparin therapy, these ranges are not based on prospective data, and if the assay result is outside the suggested therapeutic target range, current guidelines offer no advice on safely adjusting the dose.^8,71

Measuring anti-Xa activity is particularly important for pregnant women with a mechanical prosthetic heart valve who are treated with low-molecular-weight heparins. In this setting, valve thrombosis and cardioembolic events have been reported in patients with peak low-molecular-weight heparin anti-Xa assay levels below or even at the lower end of the therapeutic range, and increased bleeding risk has been reported with elevated anti-Xa levels.^71–74 Measuring trough low-molecular-weight heparin anti-Xa levels has been suggested to guide dose adjustments during pregnancy.⁷⁵

Clearance of low-molecular-weight heparins as measured by the anti-Xa assay is highly correlated with creatinine clearance.^76,77 A strong linear correlation has been demonstrated between creatine clearance and anti-Xa levels of enoxaparin after multiple therapeutic doses, and low-molecular-weight heparins accumulate in the plasma, especially in patients with creatine clearance less than 30 mL/min.⁷⁸ The risk of major bleeding is significantly increased in patients with severe renal insufficiency (creatinine clearance < 30 mL/min) not on dialysis who are treated with either prophylactic or therapeutic doses of low-molecular-weight heparin.^79–81 In a meta-analysis, the risk of bleeding with therapeutic-intensity doses of enoxaparin was 4 times higher than with prophylactic-intensity doses.⁷⁹ Although bleeding risk appears to be reduced when the enoxaparin dose is reduced by 50%,⁸ the efficacy and safety of this strategy has not been determined by prospective trials.

ANTI-Xa ASSAYS IN PATIENTS RECEIVING DIRECT ORAL ANTICOAGULANTS

Direct oral factor Xa inhibitors cannot be measured accurately by heparin anti-Xa assays. Nevertheless, such assays may be useful to assess whether clinically relevant plasma levels are present in cases of major bleeding, suspected anticoagulant failure, or patient noncompliance.⁸²

Intense research has focused on developing drug-specific chromogenic anti-Xa assays using calibrators and standards for apixaban, edoxaban, and rivaroxaban,^82,83 and good linear correlation has been shown with some assays.^82,84 In patients treated with oral factor Xa inhibitors who need to undergo an urgent invasive procedure associated with high bleeding risk, use of a specific reversal agent may be considered with drug concentrations more than 30 ng/mL measured by a drug-specific anti-Xa assay. A similar suggestion has been made for drug concentrations more than 50 ng/mL in the setting of major bleeding.⁸⁵ Unfortunately, such assays are not widely available at this time.^82,86

While drug-specific anti-Xa assays could become clinically important to guide reversal strategies, their relevance for drug monitoring remains uncertain. This is because no therapeutic target ranges have been established for any of the direct oral anticoagulants, which were approved on the basis of favorable clinical trial outcomes that neither measured nor were correlated with specific drug levels in plasma. Therefore, a specific anti-Xa level cannot yet be used as a marker of clinical efficacy for any specific oral direct Xa inhibitor.

Should clinicians abandon the activated partial thromboplastin time (aPTT) for monitoring heparin therapy in favor of tests that measure the activity of the patient’s plasma against activated factor X (anti-Xa assays)?

Although other anticoagulants are now available for preventing and treating arterial and venous thromboembolism, unfractionated heparin—which requires laboratory monitoring of therapy—is still widely used. And this monitoring can be challenging. Despite its wide use, the aPTT lacks standardization, and the role of alternative monitoring assays such as the anti-Xa assay is not well defined.

This article reviews the advantages, limitations, and clinical applicability of anti-Xa assays for monitoring therapy with unfractionated heparin and other anticoagulants.

UNFRACTIONATED HEPARIN AND WARFARIN ARE STILL WIDELY USED

Until the mid-1990s, unfractionated heparin and oral vitamin K antagonists (eg, warfarin) were the only anticoagulants widely available for clinical use. These agents have complex pharmacokinetic and pharmacodynamic properties, resulting in highly variable dosing requirements (both between patients and in individual patients) and narrow therapeutic windows, making frequent laboratory monitoring and dose adjustments mandatory.

Over the past 3 decades, other anticoagulants have been approved, including low-molecular-weight heparins, fondaparinux, parenteral direct thrombin inhibitors, and direct oral anticoagulants. While these agents have expanded the options for preventing and treating thromboembolism, unfractionated heparin and warfarin are still the most appropriate choices for many patients, eg, those with stage 4 chronic kidney disease and end-stage renal disease on dialysis, and those with mechanical heart valves.

In addition, unfractionated heparin remains the anticoagulant of choice during procedures such as hemodialysis, percutaneous transluminal angioplasty, and cardiopulmonary bypass, as well as in hospitalized and critically ill patients, who often have acute kidney injury or require frequent interruptions of therapy for invasive procedures. In these scenarios, unfractionated heparin is typically preferred because of its short plasma half-life, complete reversibility by protamine, safety regardless of renal function, and low cost compared with parenteral direct thrombin inhibitors.

As long as unfractionated heparin and warfarin remain important therapies, the need for their laboratory monitoring continues. For warfarin monitoring, the prothrombin time and international normalized ratio are validated and widely reproducible methods. But monitoring unfractionated heparin therapy remains a challenge.

UNFRACTIONATED HEPARIN’S EFFECT IS UNPREDICTABLE

Unfractionated heparin, a negatively charged mucopolysaccharide, inhibits coagulation by binding to antithrombin through the high-affinity pentasaccharide sequence.^1–6 Such binding induces a conformational change in the antithrombin molecule, converting it to a rapid inhibitor of several coagulation proteins, especially factors IIa and Xa.^2–4

Unfractionated heparin inhibits factors IIa and Xa in a 1:1 ratio, but low-molecular-weight heparins inhibit factor Xa more than factor IIa, with IIa-Xa inhibition ratios ranging from 1:2 to 1:4, owing to their smaller molecular size.⁷

One of the most important reasons for the unpredictable and highly variable individual responses to unfractionated heparin is that, infused into the blood, the large and negatively charged unfractionated heparin molecules bind nonspecifically to positively charged plasma proteins.⁷ In patients who are critically ill, have acute infections or inflammatory states, or have undergone major surgery, unfractionated heparin binds to acute-phase proteins that are elevated, particularly factor VIII. This results in fewer free heparin molecules and a variable anticoagulant effect.⁸

In contrast, low-molecular-weight heparins have longer half-lives and bind less to plasma proteins, resulting in more predictable plasma levels following subcutaneous injection.⁹

 

 

MONITORING UNFRACTIONATED HEPARIN IMPROVES OUTCOMES

In 1960, Barritt and Jordan¹⁰ conducted a small but landmark trial that established the clinical importance of unfractionated heparin for treating venous thromboembolism. None of the patients who received unfractionated heparin for acute pulmonary embolism developed a recurrence during the subsequent 2 weeks, while 50% of those who did not receive it had recurrent pulmonary embolism, fatal in half of the cases.

The importance of achieving a specific aPTT therapeutic target was not demonstrated until a 1972 study by Basu et al,¹¹ in which 162 patients with venous thromboembolism were treated with heparin with a target aPTT of 1.5 to 2.5 times the control value. Patients who suffered recurrent events had subtherapeutic aPTT values on 71% of treatment days, while the rest of the patients, with no recurrences, had subtherapeutic aPTT values only 28% of treatment days. The different outcomes could not be explained by the average daily dose of unfractionated heparin, which was similar in the patients regardless of recurrence.

Subsequent studies showed that the best outcomes occur when unfractionated heparin is given in doses high enough to rapidly achieve a therapeutic prolongation of the aPTT,^12–14 and that the total daily dose is also important in preventing recurrences.^15,16 Failure to achieve a target aPTT within 24 hours of starting unfractionated heparin is associated with increased risk of recurrent venous thromboembolism.^13,17

Raschke et al¹⁷ found that patients prospectively randomized to weight-based doses of intravenous unfractionated heparin (bolus plus infusion) achieved significantly higher rates of therapeutic aPTT within 6 hours and 24 hours after starting the infusion, and had significantly lower rates of recurrent venous thromboembolism than those randomized to a fixed unfractionated heparin protocol, without an increase in major bleeding.

Smith et al,¹⁸ in a study of 400 consecutive patients with acute pulmonary embolism treated with unfractionated heparin, found that patients who achieved a therapeutic aPTT within 24 hours had lower in-hospital and 30-day mortality rates than those who did not achieve the first therapeutic aPTT until more than 24 hours after starting unfractionated heparin infusion.

Such data lend support to the widely accepted practice and current guideline recommendation⁸ of using laboratory assays to adjust the dose of unfractionated heparin to achieve and maintain a therapeutic target. The use of dosing nomograms significantly reduces the time to achieve a therapeutic aPTT while minimizing subtherapeutic and supratherapeutic unfractionated heparin levels.^19,20

THE aPTT REFLECTS THROMBIN INHIBITION

The aPTT has a log-linear relationship with plasma concentrations of unfractionated heparin,²¹ but it was not developed specifically for monitoring unfractionated heparin therapy. Originally described in 1953 as a screening tool for hemophilia,^22–24 the aPTT is prolonged in the setting of factor deficiencies (typically with levels < 45%, except for factors VII and XIII), as well as lupus anticoagulants and therapy with parenteral direct thrombin inhibitors.^8,25,26

Because thrombin (factor IIa) is 10 times more sensitive than factor Xa to inhibition by the heparin-antithrombin complex,^4,7 thrombin inhibition appears to be the most likely mechanism by which unfractionated heparin prolongs the aPTT. In contrast, aPTT is minimally or not at all prolonged by low-molecular-weight heparins, which are predominantly factor Xa inhibitors.⁷

HEPARIN ASSAYS MEASURE UNFRACTIONATED HEPARIN ACTIVITY

While the aPTT is a surrogate marker of unfractionated heparin activity in plasma, unfractionated heparin activity can be measured more precisely by so-called heparin assays, which are typically not direct measures of the plasma concentration of heparins, but rather functional assays that provide indirect estimates. They include protamine sulfate titration assays and anti-Xa assays.

Protamine sulfate titration assays measure the amount of protamine sulfate required to neutralize heparin: the more protamine required, the greater the estimated concentration of unfractionated heparin in plasma.^8,27–29 Protamine titration assays are technically demanding, so they are rarely used clinically.

Anti-Xa assays provide a measure of the functional level of heparins in plasma.^29–33 Chromogenic anti-Xa assays are available on automated analyzers with standardized kits^29,33,34 and may be faster to perform than the aPTT.³⁵

Experiments in rabbits show that unfractionated heparin inhibits thrombus formation and extension at concentrations of 0.2 to 0.4 U/mL as measured by the protamine titration assay,²⁷ which correlated with an anti-Xa activity of 0.35 to 0.67 U/mL in a randomized controlled trial.³²

Assays that directly measure the plasma concentration of heparin exist but are not clinically relevant because they also measure heparin molecules lacking the pentasaccharide sequence, which have no anticoagulant activity.³⁶

 

 

ANTI-Xa ASSAY VS THE aPTT

Anti-Xa assays are more expensive than the aPTT and are not available in all hospitals. For these reasons, the aPTT remains the most commonly used laboratory assay for monitoring unfractionated heparin therapy.

However, the aPTT correlates poorly with the activity level of unfractionated heparin in plasma. In one study, an anti-Xa level of 0.3 U/mL corresponded to aPTT results ranging from 47 to 108 seconds.³¹ Furthermore, in studies that used a heparin therapeutic target based on an aPTT ratio 1.5 to 2.5 times the control aPTT value, the lower end of that target range was often associated with subtherapeutic plasma unfractionated heparin activity measured by anti-Xa and protamine titration assays.^28,31

Because of these limitations, individual laboratories should determine their own aPTT therapeutic target ranges for unfractionated heparin based on the response curves obtained with the reagent and coagulometer used. The optimal therapeutic aPTT range for treating acute venous thromboembolism should be defined as the aPTT range (in seconds) that correlates with a plasma activity level of unfractionated heparin of 0.3 to 0.7 U/mL based on a chromogenic anti-Xa assay, or 0.2 to 0.4 U/mL based on a protamine titration assay.^32,34–36

Nevertheless, the anticoagulant effect of unfractionated heparin as measured by the aPTT can be unpredictable and can vary widely among individuals and in the same patient.⁷ This wide variability can be explained by a number of technical and biologic variables. Different commercial aPTT reagents, different lots of the same reagent, and different reagent and instrument combinations have different sensitivities to unfractionated heparin, which can lead to variable aPTT results.³⁷ Moreover, high plasma levels of acute-phase proteins, low plasma antithrombin levels, consumptive coagulopathies, liver failure, and lupus anticoagulants may also affect the aPTT.^{7,25,32,36–41} These variables account for the poor correlation—ranging from 25% to 66%—reported between aPTT and anti-Xa assays.^32,42–48

Such discrepancies may have serious clinical implications: if a patient’s aPTT is low (subtherapeutic) or high (supratherapeutic) but the anti-Xa assay result is within the therapeutic range (0.3–0.7 units/mL), changing the dose of unfractionated heparin (guided by an aPTT nomogram) may increase the risk of bleeding or of recurrent thromboembolism.

CLINICAL APPLICABILITY OF THE ANTI-Xa ASSAY

Neither anti-Xa nor protamine titration assays are standardized across reference laboratories, but chromogenic anti-Xa assays have better interlaboratory correlation than the aPTT^49,50 and can be calibrated specifically for unfractionated or low-molecular-weight heparins.^29,33

Although reagent costs are higher for chromogenic anti-Xa assays than for the aPTT, some technical variables (described below) may partially offset the cost difference.^29,33,41 In addition, unlike the aPTT, anti-Xa assays do not need local calibration; the therapeutic range for unfractionated heparin is the same (0.3–0.7 U/mL) regardless of instrument or reagent.^33,41

Most important, studies have found that patients monitored by anti-Xa assay achieve significantly higher rates of therapeutic anticoagulation within 24 and 48 hours after starting unfractionated heparin infusion than those monitored by the aPTT. Fewer dose adjustments and repeat tests are required, which may also result in lower cost.^32,51–55

While these studies found chromogenic anti-Xa assays better for achieving laboratory end points, data regarding relevant clinical outcomes are more limited. In a retrospective, observational cohort study,⁵¹ the rate of venous thromboembolism or bleeding-related death was 2% in patients receiving unfractionated heparin therapy monitored by anti-Xa assay and 6% in patients monitored by aPTT (P = .62). Rates of major hemorrhage were also not significantly different.

In a randomized controlled trial³² in 131 patients with acute venous thromboembolism and heparin resistance, rates of recurrent venous thromboembolism were 4.6% and 6.1% in the groups randomized to anti-Xa and aPTT monitoring, respectively, whereas overall bleeding rates were 1.5% and 6.1%, respectively. Again, the differences were not statistically significant.

Heparin resistance. Some patients require unusually high doses of unfractionated heparin to achieve a therapeutic aPTT: typically, more than 35,000 U over 24 hours,^7,8,32 or total daily doses that exceed their estimated weight-based requirements. Heparin resistance has been observed in various clinical settings.^{7,8,32,37–40,59–61} Patients with heparin resistance monitored by anti-Xa had similar rates of recurrent venous thromboembolism while receiving significantly lower doses of unfractionated heparin than those monitored by the aPTT.³²

Lupus anticoagulant. Patients with the specific antiphospholipid antibody known as lupus anticoagulant frequently have a prolonged baseline aPTT,²⁵ making it an unreliable marker of anticoagulant effect for intravenous unfractionated heparin therapy.

Critically ill infants and children. Arachchillage et al³⁵ found that infants (< 1 year old) treated with intravenous unfractionated heparin in an intensive care department had only a 32.4% correlation between aPTT and anti-Xa levels, which was lower than that found in children ages 1 to 15 (66%) and adults (52%). In two-thirds of cases of discordant aPTT and anti-Xa levels, the aPTT was elevated (supratherapeutic) while the anti-Xa assay was within the therapeutic range (0.3–0.7 U/mL). Despite the lack of data on clinical outcomes (eg, rates of thrombosis and bleeding) with the use of an anti-Xa assay, it has been considered the method of choice for unfractionated heparin monitoring in critically ill children, and especially in those under age 1.^{41,44,62–64}

While anti-Xa assays may also be better for unfractionated heparin monitoring in critically ill adults, the lack of clinical outcome data from large-scale randomized trials has precluded evidence-based recommendations favoring them over the aPTT.^8,34

 

 

LIMITATIONS OF ANTI-Xa ASSAYS

Anti-Xa assays are hampered by some technical limitations:

Samples must be processed within 1 hour to avoid heparin neutralization.³⁴

Samples must be clear. Hemolyzed or opaque samples (eg, due to bilirubin levels > 6.6 mg/dL or triglyceride levels > 360 mg/dL) cannot be processed, as they can cause falsely low levels.

Exposure to other anticoagulants can interfere with the results. The anti-Xa assay may be unreliable for unfractionated heparin monitoring in patients who are transitioned from low-molecular-weight heparins, fondaparinux, or an oral factor Xa inhibitor (apixaban, betrixaban, edoxaban, rivaroxaban) to intravenous unfractionated heparin, eg, due to hospitalization or acute kidney injury.^65,66 Different reports have found that anti-Xa assays may be elevated for as long as 63 to 96 hours after the last dose of oral Xa inhibitors,^67–69 potentially resulting in underdosing of unfractionated heparin. In such settings, unfractionated heparin therapy should be monitored by the aPTT.

ANTI-Xa ASSAYS AND LOW-MOLECULAR-WEIGHT HEPARINS

Most patients receiving low-molecular-weight heparins do not need laboratory monitoring.⁸ Alhenc-Gelas et al⁷⁰ randomized patients to receive dalteparin in doses either based on weight or guided by anti-Xa assay results, and found that dose adjustments were rare and lacked clinical benefit.

The suggested therapeutic anti-Xa levels for low-molecular-weight heparins are:

• 0.5–1.2 U/mL for twice-daily enoxaparin
• 1.0–2.0 U/mL for once-daily enoxaparin or dalteparin.

Levels should be measured at peak plasma level (ie, 3–4 hours after subcutaneous injection, except during pregnancy, when it is 4–6 hours), and only after at least 3 doses of low-molecular-weight heparin.^8,71 Unlike the anti-Xa therapeutic range recommended for unfractionated heparin therapy, these ranges are not based on prospective data, and if the assay result is outside the suggested therapeutic target range, current guidelines offer no advice on safely adjusting the dose.^8,71

Measuring anti-Xa activity is particularly important for pregnant women with a mechanical prosthetic heart valve who are treated with low-molecular-weight heparins. In this setting, valve thrombosis and cardioembolic events have been reported in patients with peak low-molecular-weight heparin anti-Xa assay levels below or even at the lower end of the therapeutic range, and increased bleeding risk has been reported with elevated anti-Xa levels.^71–74 Measuring trough low-molecular-weight heparin anti-Xa levels has been suggested to guide dose adjustments during pregnancy.⁷⁵

Clearance of low-molecular-weight heparins as measured by the anti-Xa assay is highly correlated with creatinine clearance.^76,77 A strong linear correlation has been demonstrated between creatine clearance and anti-Xa levels of enoxaparin after multiple therapeutic doses, and low-molecular-weight heparins accumulate in the plasma, especially in patients with creatine clearance less than 30 mL/min.⁷⁸ The risk of major bleeding is significantly increased in patients with severe renal insufficiency (creatinine clearance < 30 mL/min) not on dialysis who are treated with either prophylactic or therapeutic doses of low-molecular-weight heparin.^79–81 In a meta-analysis, the risk of bleeding with therapeutic-intensity doses of enoxaparin was 4 times higher than with prophylactic-intensity doses.⁷⁹ Although bleeding risk appears to be reduced when the enoxaparin dose is reduced by 50%,⁸ the efficacy and safety of this strategy has not been determined by prospective trials.

ANTI-Xa ASSAYS IN PATIENTS RECEIVING DIRECT ORAL ANTICOAGULANTS

Direct oral factor Xa inhibitors cannot be measured accurately by heparin anti-Xa assays. Nevertheless, such assays may be useful to assess whether clinically relevant plasma levels are present in cases of major bleeding, suspected anticoagulant failure, or patient noncompliance.⁸²

Intense research has focused on developing drug-specific chromogenic anti-Xa assays using calibrators and standards for apixaban, edoxaban, and rivaroxaban,^82,83 and good linear correlation has been shown with some assays.^82,84 In patients treated with oral factor Xa inhibitors who need to undergo an urgent invasive procedure associated with high bleeding risk, use of a specific reversal agent may be considered with drug concentrations more than 30 ng/mL measured by a drug-specific anti-Xa assay. A similar suggestion has been made for drug concentrations more than 50 ng/mL in the setting of major bleeding.⁸⁵ Unfortunately, such assays are not widely available at this time.^82,86

While drug-specific anti-Xa assays could become clinically important to guide reversal strategies, their relevance for drug monitoring remains uncertain. This is because no therapeutic target ranges have been established for any of the direct oral anticoagulants, which were approved on the basis of favorable clinical trial outcomes that neither measured nor were correlated with specific drug levels in plasma. Therefore, a specific anti-Xa level cannot yet be used as a marker of clinical efficacy for any specific oral direct Xa inhibitor.

Should clinicians abandon the activated partial thromboplastin time (aPTT) for monitoring heparin therapy in favor of tests that measure the activity of the patient’s plasma against activated factor X (anti-Xa assays)?

Although other anticoagulants are now available for preventing and treating arterial and venous thromboembolism, unfractionated heparin—which requires laboratory monitoring of therapy—is still widely used. And this monitoring can be challenging. Despite its wide use, the aPTT lacks standardization, and the role of alternative monitoring assays such as the anti-Xa assay is not well defined.

This article reviews the advantages, limitations, and clinical applicability of anti-Xa assays for monitoring therapy with unfractionated heparin and other anticoagulants.

UNFRACTIONATED HEPARIN AND WARFARIN ARE STILL WIDELY USED

Until the mid-1990s, unfractionated heparin and oral vitamin K antagonists (eg, warfarin) were the only anticoagulants widely available for clinical use. These agents have complex pharmacokinetic and pharmacodynamic properties, resulting in highly variable dosing requirements (both between patients and in individual patients) and narrow therapeutic windows, making frequent laboratory monitoring and dose adjustments mandatory.

Over the past 3 decades, other anticoagulants have been approved, including low-molecular-weight heparins, fondaparinux, parenteral direct thrombin inhibitors, and direct oral anticoagulants. While these agents have expanded the options for preventing and treating thromboembolism, unfractionated heparin and warfarin are still the most appropriate choices for many patients, eg, those with stage 4 chronic kidney disease and end-stage renal disease on dialysis, and those with mechanical heart valves.

In addition, unfractionated heparin remains the anticoagulant of choice during procedures such as hemodialysis, percutaneous transluminal angioplasty, and cardiopulmonary bypass, as well as in hospitalized and critically ill patients, who often have acute kidney injury or require frequent interruptions of therapy for invasive procedures. In these scenarios, unfractionated heparin is typically preferred because of its short plasma half-life, complete reversibility by protamine, safety regardless of renal function, and low cost compared with parenteral direct thrombin inhibitors.

As long as unfractionated heparin and warfarin remain important therapies, the need for their laboratory monitoring continues. For warfarin monitoring, the prothrombin time and international normalized ratio are validated and widely reproducible methods. But monitoring unfractionated heparin therapy remains a challenge.

UNFRACTIONATED HEPARIN’S EFFECT IS UNPREDICTABLE

Unfractionated heparin, a negatively charged mucopolysaccharide, inhibits coagulation by binding to antithrombin through the high-affinity pentasaccharide sequence.^1–6 Such binding induces a conformational change in the antithrombin molecule, converting it to a rapid inhibitor of several coagulation proteins, especially factors IIa and Xa.^2–4

Unfractionated heparin inhibits factors IIa and Xa in a 1:1 ratio, but low-molecular-weight heparins inhibit factor Xa more than factor IIa, with IIa-Xa inhibition ratios ranging from 1:2 to 1:4, owing to their smaller molecular size.⁷

One of the most important reasons for the unpredictable and highly variable individual responses to unfractionated heparin is that, infused into the blood, the large and negatively charged unfractionated heparin molecules bind nonspecifically to positively charged plasma proteins.⁷ In patients who are critically ill, have acute infections or inflammatory states, or have undergone major surgery, unfractionated heparin binds to acute-phase proteins that are elevated, particularly factor VIII. This results in fewer free heparin molecules and a variable anticoagulant effect.⁸

In contrast, low-molecular-weight heparins have longer half-lives and bind less to plasma proteins, resulting in more predictable plasma levels following subcutaneous injection.⁹

 

 

MONITORING UNFRACTIONATED HEPARIN IMPROVES OUTCOMES

In 1960, Barritt and Jordan¹⁰ conducted a small but landmark trial that established the clinical importance of unfractionated heparin for treating venous thromboembolism. None of the patients who received unfractionated heparin for acute pulmonary embolism developed a recurrence during the subsequent 2 weeks, while 50% of those who did not receive it had recurrent pulmonary embolism, fatal in half of the cases.

The importance of achieving a specific aPTT therapeutic target was not demonstrated until a 1972 study by Basu et al,¹¹ in which 162 patients with venous thromboembolism were treated with heparin with a target aPTT of 1.5 to 2.5 times the control value. Patients who suffered recurrent events had subtherapeutic aPTT values on 71% of treatment days, while the rest of the patients, with no recurrences, had subtherapeutic aPTT values only 28% of treatment days. The different outcomes could not be explained by the average daily dose of unfractionated heparin, which was similar in the patients regardless of recurrence.

Subsequent studies showed that the best outcomes occur when unfractionated heparin is given in doses high enough to rapidly achieve a therapeutic prolongation of the aPTT,^12–14 and that the total daily dose is also important in preventing recurrences.^15,16 Failure to achieve a target aPTT within 24 hours of starting unfractionated heparin is associated with increased risk of recurrent venous thromboembolism.^13,17

Raschke et al¹⁷ found that patients prospectively randomized to weight-based doses of intravenous unfractionated heparin (bolus plus infusion) achieved significantly higher rates of therapeutic aPTT within 6 hours and 24 hours after starting the infusion, and had significantly lower rates of recurrent venous thromboembolism than those randomized to a fixed unfractionated heparin protocol, without an increase in major bleeding.

Smith et al,¹⁸ in a study of 400 consecutive patients with acute pulmonary embolism treated with unfractionated heparin, found that patients who achieved a therapeutic aPTT within 24 hours had lower in-hospital and 30-day mortality rates than those who did not achieve the first therapeutic aPTT until more than 24 hours after starting unfractionated heparin infusion.

Such data lend support to the widely accepted practice and current guideline recommendation⁸ of using laboratory assays to adjust the dose of unfractionated heparin to achieve and maintain a therapeutic target. The use of dosing nomograms significantly reduces the time to achieve a therapeutic aPTT while minimizing subtherapeutic and supratherapeutic unfractionated heparin levels.^19,20

THE aPTT REFLECTS THROMBIN INHIBITION

The aPTT has a log-linear relationship with plasma concentrations of unfractionated heparin,²¹ but it was not developed specifically for monitoring unfractionated heparin therapy. Originally described in 1953 as a screening tool for hemophilia,^22–24 the aPTT is prolonged in the setting of factor deficiencies (typically with levels < 45%, except for factors VII and XIII), as well as lupus anticoagulants and therapy with parenteral direct thrombin inhibitors.^8,25,26

Because thrombin (factor IIa) is 10 times more sensitive than factor Xa to inhibition by the heparin-antithrombin complex,^4,7 thrombin inhibition appears to be the most likely mechanism by which unfractionated heparin prolongs the aPTT. In contrast, aPTT is minimally or not at all prolonged by low-molecular-weight heparins, which are predominantly factor Xa inhibitors.⁷

HEPARIN ASSAYS MEASURE UNFRACTIONATED HEPARIN ACTIVITY

While the aPTT is a surrogate marker of unfractionated heparin activity in plasma, unfractionated heparin activity can be measured more precisely by so-called heparin assays, which are typically not direct measures of the plasma concentration of heparins, but rather functional assays that provide indirect estimates. They include protamine sulfate titration assays and anti-Xa assays.

Protamine sulfate titration assays measure the amount of protamine sulfate required to neutralize heparin: the more protamine required, the greater the estimated concentration of unfractionated heparin in plasma.^8,27–29 Protamine titration assays are technically demanding, so they are rarely used clinically.

Anti-Xa assays provide a measure of the functional level of heparins in plasma.^29–33 Chromogenic anti-Xa assays are available on automated analyzers with standardized kits^29,33,34 and may be faster to perform than the aPTT.³⁵

Experiments in rabbits show that unfractionated heparin inhibits thrombus formation and extension at concentrations of 0.2 to 0.4 U/mL as measured by the protamine titration assay,²⁷ which correlated with an anti-Xa activity of 0.35 to 0.67 U/mL in a randomized controlled trial.³²

Assays that directly measure the plasma concentration of heparin exist but are not clinically relevant because they also measure heparin molecules lacking the pentasaccharide sequence, which have no anticoagulant activity.³⁶

 

 

ANTI-Xa ASSAY VS THE aPTT

Anti-Xa assays are more expensive than the aPTT and are not available in all hospitals. For these reasons, the aPTT remains the most commonly used laboratory assay for monitoring unfractionated heparin therapy.

However, the aPTT correlates poorly with the activity level of unfractionated heparin in plasma. In one study, an anti-Xa level of 0.3 U/mL corresponded to aPTT results ranging from 47 to 108 seconds.³¹ Furthermore, in studies that used a heparin therapeutic target based on an aPTT ratio 1.5 to 2.5 times the control aPTT value, the lower end of that target range was often associated with subtherapeutic plasma unfractionated heparin activity measured by anti-Xa and protamine titration assays.^28,31

Because of these limitations, individual laboratories should determine their own aPTT therapeutic target ranges for unfractionated heparin based on the response curves obtained with the reagent and coagulometer used. The optimal therapeutic aPTT range for treating acute venous thromboembolism should be defined as the aPTT range (in seconds) that correlates with a plasma activity level of unfractionated heparin of 0.3 to 0.7 U/mL based on a chromogenic anti-Xa assay, or 0.2 to 0.4 U/mL based on a protamine titration assay.^32,34–36

Nevertheless, the anticoagulant effect of unfractionated heparin as measured by the aPTT can be unpredictable and can vary widely among individuals and in the same patient.⁷ This wide variability can be explained by a number of technical and biologic variables. Different commercial aPTT reagents, different lots of the same reagent, and different reagent and instrument combinations have different sensitivities to unfractionated heparin, which can lead to variable aPTT results.³⁷ Moreover, high plasma levels of acute-phase proteins, low plasma antithrombin levels, consumptive coagulopathies, liver failure, and lupus anticoagulants may also affect the aPTT.^{7,25,32,36–41} These variables account for the poor correlation—ranging from 25% to 66%—reported between aPTT and anti-Xa assays.^32,42–48

Such discrepancies may have serious clinical implications: if a patient’s aPTT is low (subtherapeutic) or high (supratherapeutic) but the anti-Xa assay result is within the therapeutic range (0.3–0.7 units/mL), changing the dose of unfractionated heparin (guided by an aPTT nomogram) may increase the risk of bleeding or of recurrent thromboembolism.

CLINICAL APPLICABILITY OF THE ANTI-Xa ASSAY

Neither anti-Xa nor protamine titration assays are standardized across reference laboratories, but chromogenic anti-Xa assays have better interlaboratory correlation than the aPTT^49,50 and can be calibrated specifically for unfractionated or low-molecular-weight heparins.^29,33

Although reagent costs are higher for chromogenic anti-Xa assays than for the aPTT, some technical variables (described below) may partially offset the cost difference.^29,33,41 In addition, unlike the aPTT, anti-Xa assays do not need local calibration; the therapeutic range for unfractionated heparin is the same (0.3–0.7 U/mL) regardless of instrument or reagent.^33,41

Most important, studies have found that patients monitored by anti-Xa assay achieve significantly higher rates of therapeutic anticoagulation within 24 and 48 hours after starting unfractionated heparin infusion than those monitored by the aPTT. Fewer dose adjustments and repeat tests are required, which may also result in lower cost.^32,51–55

While these studies found chromogenic anti-Xa assays better for achieving laboratory end points, data regarding relevant clinical outcomes are more limited. In a retrospective, observational cohort study,⁵¹ the rate of venous thromboembolism or bleeding-related death was 2% in patients receiving unfractionated heparin therapy monitored by anti-Xa assay and 6% in patients monitored by aPTT (P = .62). Rates of major hemorrhage were also not significantly different.

In a randomized controlled trial³² in 131 patients with acute venous thromboembolism and heparin resistance, rates of recurrent venous thromboembolism were 4.6% and 6.1% in the groups randomized to anti-Xa and aPTT monitoring, respectively, whereas overall bleeding rates were 1.5% and 6.1%, respectively. Again, the differences were not statistically significant.

Heparin resistance. Some patients require unusually high doses of unfractionated heparin to achieve a therapeutic aPTT: typically, more than 35,000 U over 24 hours,^7,8,32 or total daily doses that exceed their estimated weight-based requirements. Heparin resistance has been observed in various clinical settings.^{7,8,32,37–40,59–61} Patients with heparin resistance monitored by anti-Xa had similar rates of recurrent venous thromboembolism while receiving significantly lower doses of unfractionated heparin than those monitored by the aPTT.³²

Lupus anticoagulant. Patients with the specific antiphospholipid antibody known as lupus anticoagulant frequently have a prolonged baseline aPTT,²⁵ making it an unreliable marker of anticoagulant effect for intravenous unfractionated heparin therapy.

Critically ill infants and children. Arachchillage et al³⁵ found that infants (< 1 year old) treated with intravenous unfractionated heparin in an intensive care department had only a 32.4% correlation between aPTT and anti-Xa levels, which was lower than that found in children ages 1 to 15 (66%) and adults (52%). In two-thirds of cases of discordant aPTT and anti-Xa levels, the aPTT was elevated (supratherapeutic) while the anti-Xa assay was within the therapeutic range (0.3–0.7 U/mL). Despite the lack of data on clinical outcomes (eg, rates of thrombosis and bleeding) with the use of an anti-Xa assay, it has been considered the method of choice for unfractionated heparin monitoring in critically ill children, and especially in those under age 1.^{41,44,62–64}

While anti-Xa assays may also be better for unfractionated heparin monitoring in critically ill adults, the lack of clinical outcome data from large-scale randomized trials has precluded evidence-based recommendations favoring them over the aPTT.^8,34

 

 

LIMITATIONS OF ANTI-Xa ASSAYS

Anti-Xa assays are hampered by some technical limitations:

Samples must be processed within 1 hour to avoid heparin neutralization.³⁴

Samples must be clear. Hemolyzed or opaque samples (eg, due to bilirubin levels > 6.6 mg/dL or triglyceride levels > 360 mg/dL) cannot be processed, as they can cause falsely low levels.

Exposure to other anticoagulants can interfere with the results. The anti-Xa assay may be unreliable for unfractionated heparin monitoring in patients who are transitioned from low-molecular-weight heparins, fondaparinux, or an oral factor Xa inhibitor (apixaban, betrixaban, edoxaban, rivaroxaban) to intravenous unfractionated heparin, eg, due to hospitalization or acute kidney injury.^65,66 Different reports have found that anti-Xa assays may be elevated for as long as 63 to 96 hours after the last dose of oral Xa inhibitors,^67–69 potentially resulting in underdosing of unfractionated heparin. In such settings, unfractionated heparin therapy should be monitored by the aPTT.

ANTI-Xa ASSAYS AND LOW-MOLECULAR-WEIGHT HEPARINS

Most patients receiving low-molecular-weight heparins do not need laboratory monitoring.⁸ Alhenc-Gelas et al⁷⁰ randomized patients to receive dalteparin in doses either based on weight or guided by anti-Xa assay results, and found that dose adjustments were rare and lacked clinical benefit.

The suggested therapeutic anti-Xa levels for low-molecular-weight heparins are:

• 0.5–1.2 U/mL for twice-daily enoxaparin
• 1.0–2.0 U/mL for once-daily enoxaparin or dalteparin.

Levels should be measured at peak plasma level (ie, 3–4 hours after subcutaneous injection, except during pregnancy, when it is 4–6 hours), and only after at least 3 doses of low-molecular-weight heparin.^8,71 Unlike the anti-Xa therapeutic range recommended for unfractionated heparin therapy, these ranges are not based on prospective data, and if the assay result is outside the suggested therapeutic target range, current guidelines offer no advice on safely adjusting the dose.^8,71

Measuring anti-Xa activity is particularly important for pregnant women with a mechanical prosthetic heart valve who are treated with low-molecular-weight heparins. In this setting, valve thrombosis and cardioembolic events have been reported in patients with peak low-molecular-weight heparin anti-Xa assay levels below or even at the lower end of the therapeutic range, and increased bleeding risk has been reported with elevated anti-Xa levels.^71–74 Measuring trough low-molecular-weight heparin anti-Xa levels has been suggested to guide dose adjustments during pregnancy.⁷⁵

Clearance of low-molecular-weight heparins as measured by the anti-Xa assay is highly correlated with creatinine clearance.^76,77 A strong linear correlation has been demonstrated between creatine clearance and anti-Xa levels of enoxaparin after multiple therapeutic doses, and low-molecular-weight heparins accumulate in the plasma, especially in patients with creatine clearance less than 30 mL/min.⁷⁸ The risk of major bleeding is significantly increased in patients with severe renal insufficiency (creatinine clearance < 30 mL/min) not on dialysis who are treated with either prophylactic or therapeutic doses of low-molecular-weight heparin.^79–81 In a meta-analysis, the risk of bleeding with therapeutic-intensity doses of enoxaparin was 4 times higher than with prophylactic-intensity doses.⁷⁹ Although bleeding risk appears to be reduced when the enoxaparin dose is reduced by 50%,⁸ the efficacy and safety of this strategy has not been determined by prospective trials.

ANTI-Xa ASSAYS IN PATIENTS RECEIVING DIRECT ORAL ANTICOAGULANTS

Direct oral factor Xa inhibitors cannot be measured accurately by heparin anti-Xa assays. Nevertheless, such assays may be useful to assess whether clinically relevant plasma levels are present in cases of major bleeding, suspected anticoagulant failure, or patient noncompliance.⁸²

Intense research has focused on developing drug-specific chromogenic anti-Xa assays using calibrators and standards for apixaban, edoxaban, and rivaroxaban,^82,83 and good linear correlation has been shown with some assays.^82,84 In patients treated with oral factor Xa inhibitors who need to undergo an urgent invasive procedure associated with high bleeding risk, use of a specific reversal agent may be considered with drug concentrations more than 30 ng/mL measured by a drug-specific anti-Xa assay. A similar suggestion has been made for drug concentrations more than 50 ng/mL in the setting of major bleeding.⁸⁵ Unfortunately, such assays are not widely available at this time.^82,86

While drug-specific anti-Xa assays could become clinically important to guide reversal strategies, their relevance for drug monitoring remains uncertain. This is because no therapeutic target ranges have been established for any of the direct oral anticoagulants, which were approved on the basis of favorable clinical trial outcomes that neither measured nor were correlated with specific drug levels in plasma. Therefore, a specific anti-Xa level cannot yet be used as a marker of clinical efficacy for any specific oral direct Xa inhibitor.

So why are we, the trustworthy, having such a tough time convincing people to get routine vaccines for themselves and for their kids? In a sea of truthopenia, we need to do more.

Not everyone refuses vaccines. It is the rare patient in my examination room who, after a discussion, still steadfastly refuses to get a flu shot or pneumonia vaccine. But our dialogue has changed somewhat. Patients still tell me that they or someone they know got the flu from the flu shot or got sick from the pneumonia vaccine (explainable by discussing the immune system’s systemic anamnestic response to a vaccine in the setting of partial immunity—“It’s a good thing”). But more often, I’m hearing detailed stories from the Internet or social media. We heard a less-than-endorsing reflection on the value of vaccines from 2 potential presidential candidates, 1 being a physician, during a televised presidential primary debate. Then there are the tabloid stories, and, of course, there are the celebrity authors and TV talk show doctors touting the unsubstantiated or incompletely substantiated virtues of “anti-inflammatory” and “immune-boosting” diets and supplements as obvious and total truth, while I’m  recommending vaccinations and traditional drug therapies. Who can the patient believe? In our limited office-visit time, we must somehow put this external noise into perspective and individualize our suggestions for the patient in front of us.

Certainly the major news media research teams and the on-screen physician consultants to the major news networks have offered up evidence-based discussions on vaccination, the impact of preventable infections on the unvaccinated, and the limitations and reasonable potential benefits of specific dietary interventions and supplements. Unfortunately, their message is being contaminated by the untrusting aura that surrounds mainstream written and TV media.

Despite physicians’ continued high professional rating in the 2018 Gallup poll, some patients, families, and communities are swayed by arguments offered outside of our offices. And when it comes to our summarizing large studies published in major medical journals, the rolling echo of possible fake news and alternative facts comes to the fore. Can they really trust the establishment? There remains doubt in some patients’ minds.

The problem with measles, as Porter and Goldfarb discuss in this issue of the Journal, is that it is extremely contagious. For “herd immunity” to provide protection and prevent outbreaks, nearly everyone must be vaccinated or have natural immunity from childhood infection. Those who are at special risk from infection include the very young, who have an underdeveloped immune system, and adults who were not appropriately vaccinated (eg, those who may only have gotten a single measles vaccination as a child or whose immune system is weakened by disease or immunosuppressive drugs).

What can we do? We need, as a united front, to know the evidence that supports the relative value of vaccination of our child and adult patients and pass it on. We need to confront, accept, and explain to patients that all vaccines are not 100% successful (measles seems to be pretty close, based on the near-eradication of the disease in vaccinated communities up until now), but that even partial immunity is probably beneficial with all vaccines. We need to have a united front when discussing the bulk of evidence that debunks the vaccination-autism connection. We need to support federal and state funding so that all children can get their routine medical exams and vaccinations. We need to support sufficient financial protection for those companies who in good faith continue to develop and test new and improved vaccines for use in this country and around the world; infections can be introduced by travelers who have passed through areas endemic for infections rarely seen in the United States and who may not be aware of their own infection.

We need to live up to our Gallup poll ranking as highly trusted professionals. And we need to partner with our even more highly trusted nursing colleagues to take every opportunity to inform our patients and fight the spread of disinformation.

The morbilliform rash attributed to measles—and not to a sulfa allergy—should have been a phenomenon of the past. We didn’t need to see it again.

So why are we, the trustworthy, having such a tough time convincing people to get routine vaccines for themselves and for their kids? In a sea of truthopenia, we need to do more.

Not everyone refuses vaccines. It is the rare patient in my examination room who, after a discussion, still steadfastly refuses to get a flu shot or pneumonia vaccine. But our dialogue has changed somewhat. Patients still tell me that they or someone they know got the flu from the flu shot or got sick from the pneumonia vaccine (explainable by discussing the immune system’s systemic anamnestic response to a vaccine in the setting of partial immunity—“It’s a good thing”). But more often, I’m hearing detailed stories from the Internet or social media. We heard a less-than-endorsing reflection on the value of vaccines from 2 potential presidential candidates, 1 being a physician, during a televised presidential primary debate. Then there are the tabloid stories, and, of course, there are the celebrity authors and TV talk show doctors touting the unsubstantiated or incompletely substantiated virtues of “anti-inflammatory” and “immune-boosting” diets and supplements as obvious and total truth, while I’m  recommending vaccinations and traditional drug therapies. Who can the patient believe? In our limited office-visit time, we must somehow put this external noise into perspective and individualize our suggestions for the patient in front of us.

Certainly the major news media research teams and the on-screen physician consultants to the major news networks have offered up evidence-based discussions on vaccination, the impact of preventable infections on the unvaccinated, and the limitations and reasonable potential benefits of specific dietary interventions and supplements. Unfortunately, their message is being contaminated by the untrusting aura that surrounds mainstream written and TV media.

Despite physicians’ continued high professional rating in the 2018 Gallup poll, some patients, families, and communities are swayed by arguments offered outside of our offices. And when it comes to our summarizing large studies published in major medical journals, the rolling echo of possible fake news and alternative facts comes to the fore. Can they really trust the establishment? There remains doubt in some patients’ minds.

The problem with measles, as Porter and Goldfarb discuss in this issue of the Journal, is that it is extremely contagious. For “herd immunity” to provide protection and prevent outbreaks, nearly everyone must be vaccinated or have natural immunity from childhood infection. Those who are at special risk from infection include the very young, who have an underdeveloped immune system, and adults who were not appropriately vaccinated (eg, those who may only have gotten a single measles vaccination as a child or whose immune system is weakened by disease or immunosuppressive drugs).

What can we do? We need, as a united front, to know the evidence that supports the relative value of vaccination of our child and adult patients and pass it on. We need to confront, accept, and explain to patients that all vaccines are not 100% successful (measles seems to be pretty close, based on the near-eradication of the disease in vaccinated communities up until now), but that even partial immunity is probably beneficial with all vaccines. We need to have a united front when discussing the bulk of evidence that debunks the vaccination-autism connection. We need to support federal and state funding so that all children can get their routine medical exams and vaccinations. We need to support sufficient financial protection for those companies who in good faith continue to develop and test new and improved vaccines for use in this country and around the world; infections can be introduced by travelers who have passed through areas endemic for infections rarely seen in the United States and who may not be aware of their own infection.

We need to live up to our Gallup poll ranking as highly trusted professionals. And we need to partner with our even more highly trusted nursing colleagues to take every opportunity to inform our patients and fight the spread of disinformation.

The morbilliform rash attributed to measles—and not to a sulfa allergy—should have been a phenomenon of the past. We didn’t need to see it again.

So why are we, the trustworthy, having such a tough time convincing people to get routine vaccines for themselves and for their kids? In a sea of truthopenia, we need to do more.

Not everyone refuses vaccines. It is the rare patient in my examination room who, after a discussion, still steadfastly refuses to get a flu shot or pneumonia vaccine. But our dialogue has changed somewhat. Patients still tell me that they or someone they know got the flu from the flu shot or got sick from the pneumonia vaccine (explainable by discussing the immune system’s systemic anamnestic response to a vaccine in the setting of partial immunity—“It’s a good thing”). But more often, I’m hearing detailed stories from the Internet or social media. We heard a less-than-endorsing reflection on the value of vaccines from 2 potential presidential candidates, 1 being a physician, during a televised presidential primary debate. Then there are the tabloid stories, and, of course, there are the celebrity authors and TV talk show doctors touting the unsubstantiated or incompletely substantiated virtues of “anti-inflammatory” and “immune-boosting” diets and supplements as obvious and total truth, while I’m  recommending vaccinations and traditional drug therapies. Who can the patient believe? In our limited office-visit time, we must somehow put this external noise into perspective and individualize our suggestions for the patient in front of us.

Certainly the major news media research teams and the on-screen physician consultants to the major news networks have offered up evidence-based discussions on vaccination, the impact of preventable infections on the unvaccinated, and the limitations and reasonable potential benefits of specific dietary interventions and supplements. Unfortunately, their message is being contaminated by the untrusting aura that surrounds mainstream written and TV media.

Despite physicians’ continued high professional rating in the 2018 Gallup poll, some patients, families, and communities are swayed by arguments offered outside of our offices. And when it comes to our summarizing large studies published in major medical journals, the rolling echo of possible fake news and alternative facts comes to the fore. Can they really trust the establishment? There remains doubt in some patients’ minds.

The problem with measles, as Porter and Goldfarb discuss in this issue of the Journal, is that it is extremely contagious. For “herd immunity” to provide protection and prevent outbreaks, nearly everyone must be vaccinated or have natural immunity from childhood infection. Those who are at special risk from infection include the very young, who have an underdeveloped immune system, and adults who were not appropriately vaccinated (eg, those who may only have gotten a single measles vaccination as a child or whose immune system is weakened by disease or immunosuppressive drugs).

What can we do? We need, as a united front, to know the evidence that supports the relative value of vaccination of our child and adult patients and pass it on. We need to confront, accept, and explain to patients that all vaccines are not 100% successful (measles seems to be pretty close, based on the near-eradication of the disease in vaccinated communities up until now), but that even partial immunity is probably beneficial with all vaccines. We need to have a united front when discussing the bulk of evidence that debunks the vaccination-autism connection. We need to support federal and state funding so that all children can get their routine medical exams and vaccinations. We need to support sufficient financial protection for those companies who in good faith continue to develop and test new and improved vaccines for use in this country and around the world; infections can be introduced by travelers who have passed through areas endemic for infections rarely seen in the United States and who may not be aware of their own infection.

We need to live up to our Gallup poll ranking as highly trusted professionals. And we need to partner with our even more highly trusted nursing colleagues to take every opportunity to inform our patients and fight the spread of disinformation.

The morbilliform rash attributed to measles—and not to a sulfa allergy—should have been a phenomenon of the past. We didn’t need to see it again.

A 57-year-old woman was admitted to our hospital for progressive hypoxic respiratory failure that developed after 10 days of empiric treatment at another hospital for an exacerbation of chronic obstructive pulmonary disease (COPD).

Computed tomography (CT) showed a lesion in the upper lobe of the left lung, with new ground-glass opacities with cystic and cavitary changes raising concern for an inflammatory or infectious cause (Figure 1). Respiratory culture of expectorated secretions grew Aspergillus. Assays for beta-d-glucan and serum Aspergillus immunoglobulin G (IgG) antibodies were positive, although given the improvement in her oxygenation requirements and overall clinical status, these were thought to be trivial. Tests for immunoglobulin deficiencies and human immunodeficiency virus were negative, ruling out primary immunodeficiency. However, within the next 48 hours, her respiratory status declined, and voriconazole was started out of concern for invasive pulmonary aspergillosis based on results of serum IgG testing.

Despite 2 days of treatment with voriconazole, the patient developed respiratory failure. Repeat CT showed that the ground-glass opacities were more dense, especially in the lower lobes, and new patchy infiltrates were noted in the left lung. The patient developed a right tension pneumothorax requiring emergency intubation and chest tube insertion.¹ She subsequently developed acute abdominal pain with worsening abdominal distention, diagnosed as pneumoperitoneum. Emergency exploratory laparotomy revealed perforations in the cecum with fecal spillage, requiring ileo­cecectomy and ileostomy.

Pathologic study of bowel specimens confirmed fungal hyphae with “tree-branch” structures consistent with fungal infection in the bowel (Figure 2).

Oral voriconazole was continued. The patient’s respiratory status improved, and she no longer required supplemental oxygen. She was discharged on a regimen of oral voriconazole 200 mg twice daily. However, over the next 12 months, she had additional hospitalizations for severe sepsis from abdominal wound infections, pneumonia, and Clostridium difficile infection. She will require lifelong antifungal treatment.

INVASIVE PULMONARY ASPERGILLOSIS

Invasive pulmonary aspergillosis is the most severe form of aspergillosis and is most often seen in immunocompromised patients. The death rate is as high as 50% in neutropenic patients regardless of the time to diagnosis or effective treatment.² It becomes life-threatening as the infection enters the blood stream, leading to formation of thrombi and precipitating embolism and necrosis in the lungs.³

In immunocompetent patients, COPD, tuberculosis, bronchiectasis, liver disease, severe sepsis, and diabetes mellitus predispose to invasive pulmonary aspergillosis.² Other risk factors include long-term steroid therapy at doses equivalent to prednisone 20 mg/day for at least 13 weeks⁴ and viral infection such as influenza.⁵ Chronic use of inhaled corticosteroids has been hypothesized to increase risk.⁴

Histopathologic confirmation of fungal elements is the gold standard for diagnosis.³ New biomarkers such as beta-d-glucan have shown promise in enabling earlier diagnosis to allow effective treatment of disseminated aspergillosis, as in our patient.⁶

TAKE-HOME MESSAGE

Although not common, invasive aspergillosis can occur in immunocompetent and near-immunocompetent patients, particularly those with COPD or other underlying lung disease.

Acknowledgment: The authors thank Kimberley Woodward, MD, Inova Fairfax Hospital, Falls Church, VA, for her study of the bowel specimen and for providing the histology slide.

A 57-year-old woman was admitted to our hospital for progressive hypoxic respiratory failure that developed after 10 days of empiric treatment at another hospital for an exacerbation of chronic obstructive pulmonary disease (COPD).

Computed tomography (CT) showed a lesion in the upper lobe of the left lung, with new ground-glass opacities with cystic and cavitary changes raising concern for an inflammatory or infectious cause (Figure 1). Respiratory culture of expectorated secretions grew Aspergillus. Assays for beta-d-glucan and serum Aspergillus immunoglobulin G (IgG) antibodies were positive, although given the improvement in her oxygenation requirements and overall clinical status, these were thought to be trivial. Tests for immunoglobulin deficiencies and human immunodeficiency virus were negative, ruling out primary immunodeficiency. However, within the next 48 hours, her respiratory status declined, and voriconazole was started out of concern for invasive pulmonary aspergillosis based on results of serum IgG testing.

Despite 2 days of treatment with voriconazole, the patient developed respiratory failure. Repeat CT showed that the ground-glass opacities were more dense, especially in the lower lobes, and new patchy infiltrates were noted in the left lung. The patient developed a right tension pneumothorax requiring emergency intubation and chest tube insertion.¹ She subsequently developed acute abdominal pain with worsening abdominal distention, diagnosed as pneumoperitoneum. Emergency exploratory laparotomy revealed perforations in the cecum with fecal spillage, requiring ileo­cecectomy and ileostomy.

Pathologic study of bowel specimens confirmed fungal hyphae with “tree-branch” structures consistent with fungal infection in the bowel (Figure 2).

Oral voriconazole was continued. The patient’s respiratory status improved, and she no longer required supplemental oxygen. She was discharged on a regimen of oral voriconazole 200 mg twice daily. However, over the next 12 months, she had additional hospitalizations for severe sepsis from abdominal wound infections, pneumonia, and Clostridium difficile infection. She will require lifelong antifungal treatment.

INVASIVE PULMONARY ASPERGILLOSIS

Invasive pulmonary aspergillosis is the most severe form of aspergillosis and is most often seen in immunocompromised patients. The death rate is as high as 50% in neutropenic patients regardless of the time to diagnosis or effective treatment.² It becomes life-threatening as the infection enters the blood stream, leading to formation of thrombi and precipitating embolism and necrosis in the lungs.³

In immunocompetent patients, COPD, tuberculosis, bronchiectasis, liver disease, severe sepsis, and diabetes mellitus predispose to invasive pulmonary aspergillosis.² Other risk factors include long-term steroid therapy at doses equivalent to prednisone 20 mg/day for at least 13 weeks⁴ and viral infection such as influenza.⁵ Chronic use of inhaled corticosteroids has been hypothesized to increase risk.⁴

Histopathologic confirmation of fungal elements is the gold standard for diagnosis.³ New biomarkers such as beta-d-glucan have shown promise in enabling earlier diagnosis to allow effective treatment of disseminated aspergillosis, as in our patient.⁶

TAKE-HOME MESSAGE

Although not common, invasive aspergillosis can occur in immunocompetent and near-immunocompetent patients, particularly those with COPD or other underlying lung disease.

Acknowledgment: The authors thank Kimberley Woodward, MD, Inova Fairfax Hospital, Falls Church, VA, for her study of the bowel specimen and for providing the histology slide.

A 57-year-old woman was admitted to our hospital for progressive hypoxic respiratory failure that developed after 10 days of empiric treatment at another hospital for an exacerbation of chronic obstructive pulmonary disease (COPD).

Computed tomography (CT) showed a lesion in the upper lobe of the left lung, with new ground-glass opacities with cystic and cavitary changes raising concern for an inflammatory or infectious cause (Figure 1). Respiratory culture of expectorated secretions grew Aspergillus. Assays for beta-d-glucan and serum Aspergillus immunoglobulin G (IgG) antibodies were positive, although given the improvement in her oxygenation requirements and overall clinical status, these were thought to be trivial. Tests for immunoglobulin deficiencies and human immunodeficiency virus were negative, ruling out primary immunodeficiency. However, within the next 48 hours, her respiratory status declined, and voriconazole was started out of concern for invasive pulmonary aspergillosis based on results of serum IgG testing.

Despite 2 days of treatment with voriconazole, the patient developed respiratory failure. Repeat CT showed that the ground-glass opacities were more dense, especially in the lower lobes, and new patchy infiltrates were noted in the left lung. The patient developed a right tension pneumothorax requiring emergency intubation and chest tube insertion.¹ She subsequently developed acute abdominal pain with worsening abdominal distention, diagnosed as pneumoperitoneum. Emergency exploratory laparotomy revealed perforations in the cecum with fecal spillage, requiring ileo­cecectomy and ileostomy.

Pathologic study of bowel specimens confirmed fungal hyphae with “tree-branch” structures consistent with fungal infection in the bowel (Figure 2).

Oral voriconazole was continued. The patient’s respiratory status improved, and she no longer required supplemental oxygen. She was discharged on a regimen of oral voriconazole 200 mg twice daily. However, over the next 12 months, she had additional hospitalizations for severe sepsis from abdominal wound infections, pneumonia, and Clostridium difficile infection. She will require lifelong antifungal treatment.

INVASIVE PULMONARY ASPERGILLOSIS

Invasive pulmonary aspergillosis is the most severe form of aspergillosis and is most often seen in immunocompromised patients. The death rate is as high as 50% in neutropenic patients regardless of the time to diagnosis or effective treatment.² It becomes life-threatening as the infection enters the blood stream, leading to formation of thrombi and precipitating embolism and necrosis in the lungs.³

In immunocompetent patients, COPD, tuberculosis, bronchiectasis, liver disease, severe sepsis, and diabetes mellitus predispose to invasive pulmonary aspergillosis.² Other risk factors include long-term steroid therapy at doses equivalent to prednisone 20 mg/day for at least 13 weeks⁴ and viral infection such as influenza.⁵ Chronic use of inhaled corticosteroids has been hypothesized to increase risk.⁴

Histopathologic confirmation of fungal elements is the gold standard for diagnosis.³ New biomarkers such as beta-d-glucan have shown promise in enabling earlier diagnosis to allow effective treatment of disseminated aspergillosis, as in our patient.⁶

TAKE-HOME MESSAGE

Although not common, invasive aspergillosis can occur in immunocompetent and near-immunocompetent patients, particularly those with COPD or other underlying lung disease.

Acknowledgment: The authors thank Kimberley Woodward, MD, Inova Fairfax Hospital, Falls Church, VA, for her study of the bowel specimen and for providing the histology slide.

No. After thoracentesis, chest radiography or another lung imaging study should be done only if pneumothorax is suspected, if thoracentesis requires more than 1 attempt, if the patient is on mechanical ventilation or has pre-existing lung disease, or if a large volume (> 1,500 mL) of fluid is removed. Radiography is also usually not necessary after diagnostic thoracentesis in a patient breathing spontaneously. In most cases, pneumothorax found incidentally after thoracentesis does not require decompression and can be managed supportively.

WHAT ARE THE RISKS OF THORACENTESIS?

Thoracentesis is a minimally invasive procedure usually performed at the bedside that involves insertion of a needle into the pleural cavity for drainage of fluid.¹ Diagnostic thoracentesis should be done in most cases of a new pleural effusion unless the effusion is small and with a clear diagnosis, or in cases of typical heart failure.

Therapeutic thoracentesis, often called large-volume thoracentesis, aims to improve symptoms such as dyspnea attributed to the pleural effusion by removing at least 1 L of pleural fluid. The presence of active respiratory symptoms and suspicion of infected pleural effusion should lead to thoracentesis as soon as possible.

Complications of thoracentesis may be benign, such as pain and anxiety associated with the procedure and external bleeding at the site of needle insertion. Pneumothorax is the most common serious procedural complication and the principal reason to order postprocedural chest radiography.¹ Less common complications include hemothorax, re-expansion pulmonary edema, infection, subdiaphragmatic organ puncture, and procedure-related death. Bleeding complications and hemothorax are rare even in patients with underlying coagulopathy.²

Point-of-care pleural ultrasonography is now considered the standard of care to guide optimal needle location for the procedure and to exclude other conditions that can mimic pleural effusion on chest radiography, such as lung consolidation and atelectasis.³ High proficiency in the use of preprocedural point-of-care ultrasonography reduces the rate of procedural complications, though it does not eliminate the risk entirely.^3,4

Factors associated with higher rates of complications include lack of operator proficiency, poor understanding of the anatomy, poor patient positioning, poor patient cooperation with the procedure, lack of availability of bedside ultrasonography, and drainage of more than 1,500 mL of fluid. Addressing these factors has been shown to decrease the risk of pneumothorax and infection.^1–5

HOW OFTEN DOES PNEUMOTHORAX OCCUR AFTER THORACENTESIS?

Several early studies have examined the incidence of pneumothorax after thoracentesis. Lack of ultrasonography use likely explains a higher incidence of complications in early studies: rates of pneumothorax after thoracentesis without ultrasonographic guidance ranged from 5.2% to 26%.^6,7

Gervais et al⁸ analyzed thoracentesis with ultrasonographic guidance in 434 patients, 92 of whom were intubated, and reported that pneumothorax occurred in 10 patients, of whom 6 were intubated. Two of the intubated patients required chest tubes. Other studies have confirmed the low incidence of pneumothorax in patients undergoing thoracentesis, with rates such as 0.61%,¹ 5%,9 and 4%.¹⁰

The major predictor of postprocedural pneumothorax was the presence of symptoms such as chest pain and dyspnea. No intervention was necessary for most cases of pneumothorax in asymptomatic patients. The more widespread use of procedural ultrasonography may explain some discrepancies between the early^5,6 and more recent studies.^1,8–10

Several studies have demonstrated that postprocedural radiography is unnecessary unless a complication is suspected based on the patient’s symptoms or the need to demonstrate lung re-expansion.^1,4,9,10 Clinical suspicion and the patient’s symptoms are the major predictors of procedure-related pneumothorax requiring treatment with a chest tube. Otherwise, incidentally discovered pneumothorax can usually be observed and managed supportively.

 

 

WHAT MECHANISMS UNDERLIE POSTPROCEDURAL PNEUMOTHORAX?

Major causes of pneumothorax in patients undergoing thoracentesis are direct puncture during needle or catheter insertion, the introduction of air through the needle or catheter into the pleural cavity, and the inability of the ipsilateral lung to fully expand after drainage of a large volume of fluid, known as pneumothorax ex vacuo.⁵

Pneumothorax ex vacuo may be seen in patients with medical conditions such as endobronchial obstruction, pleural scarring from long-standing pleural effusion, and lung malignancy, all of which can impair the lung’s ability to expand after removal of a large volume of pleural fluid. It is believed that transient parenchymal pleural fistulae form if the lung cannot expand, causing air leakage into the pleural cavity.^5,8,9 Pleural manometry to monitor changes in pleural pressure and elastance can decrease the rates of pneumothorax ex vacuo in patients with the above risk factors.⁵

WHEN IS RADIOGRAPHY INDICATED AFTER THORACENTESIS?

Current literature suggests that imaging to evaluate for postprocedural complications should be done if there is suspicion of a complication, if thoracentesis required multiple attempts, if the procedure caused aspiration of air, if the patient has advanced lung disease, if the patient is scheduled to undergo thoracic radiation, if the patient is on mechanical ventilation, and after therapeutic thoracentesis if a large volume of fluid is removed.^1–10 Routine chest radiography after thoracentesis is not supported in the literature in the absence of these risk factors.

Some practitioners order chest imaging after therapeutic thoracentesis to assess for residual pleural fluid and for visualization of other abnormalities previously hidden by pleural effusion, rather than simply to exclude postprocedural pneumothorax. Alternatively, postprocedural bedside pleural ultrasonography with recording of images can be done to assess for complications and residual pleural fluid volume without exposing the patient to radiation.¹¹

Needle decompression and chest tube insertion should be considered in patients with tension pneumothorax, large pneumothorax (distance from the chest wall to the visceral pleural line of at least 2 cm), mechanical ventilation, progressing pneumothorax, and symptoms.

KEY POINTS

• Pneumothorax is a rare complication of thoracentesis when performed by a skilled operator using ultrasonographic guidance.
• Mechanisms behind the occurrence of pneumothorax are direct lung puncture, introduction of air into the pleural cavity, and pneumothorax ex vacuo.
• In asymptomatic patients, pneumothorax after thoracentesis rarely requires intervention beyond supportive care and close observation.
• Factors such as multiple thoracentesis attempts, symptoms, clinical suspicion, air aspiration during thoracentesis, presence of previous lung disease, and removal of a large volume of fluid may require postprocedural lung imaging (eg, bedside ultrasonography, radiography).

No. After thoracentesis, chest radiography or another lung imaging study should be done only if pneumothorax is suspected, if thoracentesis requires more than 1 attempt, if the patient is on mechanical ventilation or has pre-existing lung disease, or if a large volume (> 1,500 mL) of fluid is removed. Radiography is also usually not necessary after diagnostic thoracentesis in a patient breathing spontaneously. In most cases, pneumothorax found incidentally after thoracentesis does not require decompression and can be managed supportively.

WHAT ARE THE RISKS OF THORACENTESIS?

Thoracentesis is a minimally invasive procedure usually performed at the bedside that involves insertion of a needle into the pleural cavity for drainage of fluid.¹ Diagnostic thoracentesis should be done in most cases of a new pleural effusion unless the effusion is small and with a clear diagnosis, or in cases of typical heart failure.

Therapeutic thoracentesis, often called large-volume thoracentesis, aims to improve symptoms such as dyspnea attributed to the pleural effusion by removing at least 1 L of pleural fluid. The presence of active respiratory symptoms and suspicion of infected pleural effusion should lead to thoracentesis as soon as possible.

Complications of thoracentesis may be benign, such as pain and anxiety associated with the procedure and external bleeding at the site of needle insertion. Pneumothorax is the most common serious procedural complication and the principal reason to order postprocedural chest radiography.¹ Less common complications include hemothorax, re-expansion pulmonary edema, infection, subdiaphragmatic organ puncture, and procedure-related death. Bleeding complications and hemothorax are rare even in patients with underlying coagulopathy.²

Point-of-care pleural ultrasonography is now considered the standard of care to guide optimal needle location for the procedure and to exclude other conditions that can mimic pleural effusion on chest radiography, such as lung consolidation and atelectasis.³ High proficiency in the use of preprocedural point-of-care ultrasonography reduces the rate of procedural complications, though it does not eliminate the risk entirely.^3,4

Factors associated with higher rates of complications include lack of operator proficiency, poor understanding of the anatomy, poor patient positioning, poor patient cooperation with the procedure, lack of availability of bedside ultrasonography, and drainage of more than 1,500 mL of fluid. Addressing these factors has been shown to decrease the risk of pneumothorax and infection.^1–5

HOW OFTEN DOES PNEUMOTHORAX OCCUR AFTER THORACENTESIS?

Several early studies have examined the incidence of pneumothorax after thoracentesis. Lack of ultrasonography use likely explains a higher incidence of complications in early studies: rates of pneumothorax after thoracentesis without ultrasonographic guidance ranged from 5.2% to 26%.^6,7

Gervais et al⁸ analyzed thoracentesis with ultrasonographic guidance in 434 patients, 92 of whom were intubated, and reported that pneumothorax occurred in 10 patients, of whom 6 were intubated. Two of the intubated patients required chest tubes. Other studies have confirmed the low incidence of pneumothorax in patients undergoing thoracentesis, with rates such as 0.61%,¹ 5%,9 and 4%.¹⁰

The major predictor of postprocedural pneumothorax was the presence of symptoms such as chest pain and dyspnea. No intervention was necessary for most cases of pneumothorax in asymptomatic patients. The more widespread use of procedural ultrasonography may explain some discrepancies between the early^5,6 and more recent studies.^1,8–10

Several studies have demonstrated that postprocedural radiography is unnecessary unless a complication is suspected based on the patient’s symptoms or the need to demonstrate lung re-expansion.^1,4,9,10 Clinical suspicion and the patient’s symptoms are the major predictors of procedure-related pneumothorax requiring treatment with a chest tube. Otherwise, incidentally discovered pneumothorax can usually be observed and managed supportively.

 

 

WHAT MECHANISMS UNDERLIE POSTPROCEDURAL PNEUMOTHORAX?

Major causes of pneumothorax in patients undergoing thoracentesis are direct puncture during needle or catheter insertion, the introduction of air through the needle or catheter into the pleural cavity, and the inability of the ipsilateral lung to fully expand after drainage of a large volume of fluid, known as pneumothorax ex vacuo.⁵

Pneumothorax ex vacuo may be seen in patients with medical conditions such as endobronchial obstruction, pleural scarring from long-standing pleural effusion, and lung malignancy, all of which can impair the lung’s ability to expand after removal of a large volume of pleural fluid. It is believed that transient parenchymal pleural fistulae form if the lung cannot expand, causing air leakage into the pleural cavity.^5,8,9 Pleural manometry to monitor changes in pleural pressure and elastance can decrease the rates of pneumothorax ex vacuo in patients with the above risk factors.⁵

WHEN IS RADIOGRAPHY INDICATED AFTER THORACENTESIS?

Current literature suggests that imaging to evaluate for postprocedural complications should be done if there is suspicion of a complication, if thoracentesis required multiple attempts, if the procedure caused aspiration of air, if the patient has advanced lung disease, if the patient is scheduled to undergo thoracic radiation, if the patient is on mechanical ventilation, and after therapeutic thoracentesis if a large volume of fluid is removed.^1–10 Routine chest radiography after thoracentesis is not supported in the literature in the absence of these risk factors.

Some practitioners order chest imaging after therapeutic thoracentesis to assess for residual pleural fluid and for visualization of other abnormalities previously hidden by pleural effusion, rather than simply to exclude postprocedural pneumothorax. Alternatively, postprocedural bedside pleural ultrasonography with recording of images can be done to assess for complications and residual pleural fluid volume without exposing the patient to radiation.¹¹

Needle decompression and chest tube insertion should be considered in patients with tension pneumothorax, large pneumothorax (distance from the chest wall to the visceral pleural line of at least 2 cm), mechanical ventilation, progressing pneumothorax, and symptoms.

KEY POINTS

• Pneumothorax is a rare complication of thoracentesis when performed by a skilled operator using ultrasonographic guidance.
• Mechanisms behind the occurrence of pneumothorax are direct lung puncture, introduction of air into the pleural cavity, and pneumothorax ex vacuo.
• In asymptomatic patients, pneumothorax after thoracentesis rarely requires intervention beyond supportive care and close observation.
• Factors such as multiple thoracentesis attempts, symptoms, clinical suspicion, air aspiration during thoracentesis, presence of previous lung disease, and removal of a large volume of fluid may require postprocedural lung imaging (eg, bedside ultrasonography, radiography).

No. After thoracentesis, chest radiography or another lung imaging study should be done only if pneumothorax is suspected, if thoracentesis requires more than 1 attempt, if the patient is on mechanical ventilation or has pre-existing lung disease, or if a large volume (> 1,500 mL) of fluid is removed. Radiography is also usually not necessary after diagnostic thoracentesis in a patient breathing spontaneously. In most cases, pneumothorax found incidentally after thoracentesis does not require decompression and can be managed supportively.

WHAT ARE THE RISKS OF THORACENTESIS?

Thoracentesis is a minimally invasive procedure usually performed at the bedside that involves insertion of a needle into the pleural cavity for drainage of fluid.¹ Diagnostic thoracentesis should be done in most cases of a new pleural effusion unless the effusion is small and with a clear diagnosis, or in cases of typical heart failure.

Therapeutic thoracentesis, often called large-volume thoracentesis, aims to improve symptoms such as dyspnea attributed to the pleural effusion by removing at least 1 L of pleural fluid. The presence of active respiratory symptoms and suspicion of infected pleural effusion should lead to thoracentesis as soon as possible.

Complications of thoracentesis may be benign, such as pain and anxiety associated with the procedure and external bleeding at the site of needle insertion. Pneumothorax is the most common serious procedural complication and the principal reason to order postprocedural chest radiography.¹ Less common complications include hemothorax, re-expansion pulmonary edema, infection, subdiaphragmatic organ puncture, and procedure-related death. Bleeding complications and hemothorax are rare even in patients with underlying coagulopathy.²

Point-of-care pleural ultrasonography is now considered the standard of care to guide optimal needle location for the procedure and to exclude other conditions that can mimic pleural effusion on chest radiography, such as lung consolidation and atelectasis.³ High proficiency in the use of preprocedural point-of-care ultrasonography reduces the rate of procedural complications, though it does not eliminate the risk entirely.^3,4

Factors associated with higher rates of complications include lack of operator proficiency, poor understanding of the anatomy, poor patient positioning, poor patient cooperation with the procedure, lack of availability of bedside ultrasonography, and drainage of more than 1,500 mL of fluid. Addressing these factors has been shown to decrease the risk of pneumothorax and infection.^1–5

HOW OFTEN DOES PNEUMOTHORAX OCCUR AFTER THORACENTESIS?

Several early studies have examined the incidence of pneumothorax after thoracentesis. Lack of ultrasonography use likely explains a higher incidence of complications in early studies: rates of pneumothorax after thoracentesis without ultrasonographic guidance ranged from 5.2% to 26%.^6,7

Gervais et al⁸ analyzed thoracentesis with ultrasonographic guidance in 434 patients, 92 of whom were intubated, and reported that pneumothorax occurred in 10 patients, of whom 6 were intubated. Two of the intubated patients required chest tubes. Other studies have confirmed the low incidence of pneumothorax in patients undergoing thoracentesis, with rates such as 0.61%,¹ 5%,9 and 4%.¹⁰

The major predictor of postprocedural pneumothorax was the presence of symptoms such as chest pain and dyspnea. No intervention was necessary for most cases of pneumothorax in asymptomatic patients. The more widespread use of procedural ultrasonography may explain some discrepancies between the early^5,6 and more recent studies.^1,8–10

Several studies have demonstrated that postprocedural radiography is unnecessary unless a complication is suspected based on the patient’s symptoms or the need to demonstrate lung re-expansion.^1,4,9,10 Clinical suspicion and the patient’s symptoms are the major predictors of procedure-related pneumothorax requiring treatment with a chest tube. Otherwise, incidentally discovered pneumothorax can usually be observed and managed supportively.

 

 

WHAT MECHANISMS UNDERLIE POSTPROCEDURAL PNEUMOTHORAX?

Major causes of pneumothorax in patients undergoing thoracentesis are direct puncture during needle or catheter insertion, the introduction of air through the needle or catheter into the pleural cavity, and the inability of the ipsilateral lung to fully expand after drainage of a large volume of fluid, known as pneumothorax ex vacuo.⁵

Pneumothorax ex vacuo may be seen in patients with medical conditions such as endobronchial obstruction, pleural scarring from long-standing pleural effusion, and lung malignancy, all of which can impair the lung’s ability to expand after removal of a large volume of pleural fluid. It is believed that transient parenchymal pleural fistulae form if the lung cannot expand, causing air leakage into the pleural cavity.^5,8,9 Pleural manometry to monitor changes in pleural pressure and elastance can decrease the rates of pneumothorax ex vacuo in patients with the above risk factors.⁵

WHEN IS RADIOGRAPHY INDICATED AFTER THORACENTESIS?

Current literature suggests that imaging to evaluate for postprocedural complications should be done if there is suspicion of a complication, if thoracentesis required multiple attempts, if the procedure caused aspiration of air, if the patient has advanced lung disease, if the patient is scheduled to undergo thoracic radiation, if the patient is on mechanical ventilation, and after therapeutic thoracentesis if a large volume of fluid is removed.^1–10 Routine chest radiography after thoracentesis is not supported in the literature in the absence of these risk factors.

Some practitioners order chest imaging after therapeutic thoracentesis to assess for residual pleural fluid and for visualization of other abnormalities previously hidden by pleural effusion, rather than simply to exclude postprocedural pneumothorax. Alternatively, postprocedural bedside pleural ultrasonography with recording of images can be done to assess for complications and residual pleural fluid volume without exposing the patient to radiation.¹¹

Needle decompression and chest tube insertion should be considered in patients with tension pneumothorax, large pneumothorax (distance from the chest wall to the visceral pleural line of at least 2 cm), mechanical ventilation, progressing pneumothorax, and symptoms.

KEY POINTS

• Pneumothorax is a rare complication of thoracentesis when performed by a skilled operator using ultrasonographic guidance.
• Mechanisms behind the occurrence of pneumothorax are direct lung puncture, introduction of air into the pleural cavity, and pneumothorax ex vacuo.
• In asymptomatic patients, pneumothorax after thoracentesis rarely requires intervention beyond supportive care and close observation.
• Factors such as multiple thoracentesis attempts, symptoms, clinical suspicion, air aspiration during thoracentesis, presence of previous lung disease, and removal of a large volume of fluid may require postprocedural lung imaging (eg, bedside ultrasonography, radiography).

A 69-year-old woman was admitted to the hospital with double vision, weakness in the lower extremities, sensory loss, pain, and falls. Her symptoms started with sudden onset of horizontal diplopia 6 weeks before, followed by gradually worsening lower-extremity weakness, as well as ataxia and patchy and bilateral radicular burning leg pain more pronounced on the right. Her medical history included narcolepsy, obstructive sleep apnea, hypertension, hyperlipidemia, and bilateral knee replacements for osteoarthritis.

Neurologic examination showed inability to abduct the right eye, bilateral hip flexion weakness, decreased pinprick response, decreased proprioception, and diminished muscle stretch reflexes in the lower extremities. Magnetic resonance imaging (MRI) of the brain without contrast and magnetic resonance angiography of the brain and carotid arteries showed no evidence of acute stroke. No abnormalities were noted on electrocardiography and echocardiography.

A diagnosis of idiopathic peripheral neuropathy was made, and outpatient physical therapy was recommended. Over the subsequent 2 weeks, her condition declined to the point where she needed a walker. She continued to have worsening leg weakness with falls, prompting hospital readmission.

INITIAL EVALUATION

In addition to her diplopia and weakness, she said she had lost 15 pounds since the onset of symptoms and had experienced symptoms suggesting urinary retention.

Physical examination

Her temperature was 37°C (98.6°F), heart rate 79 beats per minute, blood pressure 117/86 mm Hg, respiratory rate 14 breaths per minute, and oxygen saturation 98% on room air. Examination of the head, neck, heart, lung, abdomen, lymph nodes, and extremities yielded nothing remarkable except for chronic venous changes in the lower extremities.

The neurologic examination showed incomplete lateral gaze bilaterally (cranial nerve VI dysfunction). Strength in the upper extremities was normal. In the legs, the Medical Research Council scale score for proximal muscle strength was 2 to 3 out of 5, and for distal muscles 3 to 4 out of 5, with the right side worse than the left and flexors and extensors affected equally. Muscle stretch reflexes were absent in both lower extremities and the left upper extremity, but intact in the right upper extremity. No abnormal corticospinal tract reflexes were elicited.

Sensory testing revealed diminished pin-prick perception in a length-dependent fashion in the lower extremities, reduced 50% compared with the hands. Gait could not be assessed due to weakness.

Initial laboratory testing

Results of initial laboratory tests—complete blood cell count, complete metabolic panel, erythrocyte sedimentation rate, C-reactive protein, thyroid-stimulating hormone, and hemoglobin A_1c—were unremarkable.

 

 

FURTHER EVALUATION AND DIFFERENTIAL DIAGNOSIS

1. Which of the following is the most likely diagnosis at this point?

• Cerebral infarction
• Guillain-Barré syndrome
• Progressive polyneuropathy
• Transverse myelitis
• Polyradiculopathy

In the absence of definitive diagnostic tests, all of the above options were considered in the differential diagnosis for this patient.

Cerebral infarction

Although acute-onset diplopia can be explained by brainstem stroke involving cranial nerve nuclei or their projections, the onset of diplopia with progressive bilateral lower-extremity weakness makes stroke unlikely. Flaccid paralysis, areflexia of the lower extremities, and sensory involvement can also be caused by acute anterior spinal artery occlusion leading to spinal cord infarction; however, the deficits are usually maximal at onset.

Guillain-Barré syndrome

The combination of acute-subacute progressive ascending weakness, sensory involvement, and diminished or absent reflexes is typical of Guillain-Barré syndrome. Cranial nerve involvement can overlap with the more typical features of the syndrome. However, most patients reach the nadir of their disease by 4 weeks after initial symptom onset, even without treatment.¹ This patient’s condition continued to worsen over 8 weeks. In addition, the asymmetric lower-extremity weakness and sparing of the arms are atypical for Guillain-Barré syndrome.

Given the progression of symptoms, chronic inflammatory demyelinating polyneuropathy is also a consideration, typically presenting as a relapsing or progressive neuropathy in proximal and distal muscles and worsening over at least an 8-week period.²

The initial workup for Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy includes lumbar puncture to assess for albuminocytologic dissociation (elevated protein with normal white blood cell count) in cerebrospinal fluid (CSF), and electromyography (EMG) to assess for neuro­physiologic evidence of peripheral nerve demyelination. In Miller-Fisher syndrome, a rare variant of Guillain-Barré syndrome characterized by ataxia, ophthalmoparesis, and areflexia, serum ganglioside antibodies to GQ1b are found in over 90% of patients.^3,4 Although MRI of the spine is not necessary to diagnose Guillain-Barré syndrome, it is often done to exclude other causes of lower-extremity weakness such as spinal cord or cauda equina compression that would require urgent neurosurgical consultation. MRI can support the diagnosis of Guillain-Barré syndrome when it reveals enhancement of the spinal nerve roots or cauda equina.

Other polyneuropathies

Polyneuropathy is caused by a variety of diseases that affect the function of peripheral motor, sensory, or autonomic nerves. The differential diagnosis is broad and involves inflammatory diseases (including autoimmune and paraneoplastic causes), hereditary disorders, infection, toxicity, and ischemic and nutritional deficiencies.⁵ Polyneuropathy can present in a distal-predominant, generalized, or asymmetric pattern involving individual nerve trunks termed “mononeuropathy multiplex,” as in our patient’s presentation. The initial workup includes EMG and a battery of serologic tests. In cases of severe and progressive polyneuropathy, nerve biopsy can assess for the presence of vasculitis, amyloidosis, and paraprotein deposition.

Transverse myelitis

Transverse myelitis is an inflammatory myelopathy that usually presents with acute or subacute weakness of the upper extremities or lower extremities, or both, corresponding to the level of the lesion, hyperreflexia, bladder and bowel dysfunction, spinal level of sensory loss, and autonomic involvement.⁶ The differential diagnosis of acute myelopathy includes:

• Infection (eg, herpes simplex virus, West Nile virus, Lyme disease, Mycoplasma pneumoniae, human immunodeficiency virus)
• Systemic inflammatory disease (systemic lupus erythematosus, sarcoidosis, Sjögren syndrome, scleroderma, paraneoplastic syndrome)
• Central nervous system demyelinating disease (acute disseminated encephalomyelitis, multiple sclerosis, neuromyelitis optica)
• Vascular malformation (dural arteriovenous fistula)
• Compression due to tumor, bleeding, disc herniation, infection, or abscess.

The workup involves laboratory tests to exclude systemic inflammatory and infectious causes, as well as MRI of the spine with and without contrast to identify a causative lesion. Lumbar puncture and CSF analysis may show pleocytosis, elevated protein concentration, and increased intrathecal immunoglobulin G (IgG) index.⁷

Although our patient’s presentation with subacute lower-extremity weakness, sensory changes, and bladder dysfunction were consistent with transverse myelitis, her cranial nerve abnormalities would be atypical for it.

Polyradiculopathy


Polyradiculopathy has many possible causes. In the United States, the most common causes are lumbar spondylosis, lumbar canal stenosis, and diabetic polyradiculoneuropathy.

When multiple spinal segments are affected, leptomeningeal disease involving the arachnoid and pia mater should be considered. Causes include malignant invasion, inflammatory cell accumulation, and protein deposition, leading to patchy but widespread dysfunction of spinal nerve roots and cranial nerves. Specific causes are myriad and include carcinomatous meningitis,⁸ syphilis, tuberculosis, sarcoidosis, and paraproteinemias. CSF and MRI changes are often nonspecific, leading to the need for meningeal biopsy for diagnosis.

 

 

CASE CONTINUED

During her hospitalization, our patient developed acute right upper and lower facial weakness consistent with peripheral facial mononeuropathy. Bilateral lower-extremity weakness progressed to disabling paraparesis.

She underwent lumbar puncture and CSF analysis (Table 1). The most notable findings were significant pleocytosis (72% lymphocytic predominance), protein elevation, and elevated IgG index (indicative of elevated intrathecal immunoglobulin synthesis in the central nervous system). Viral, bacterial, and fungal studies were negative. Guillain-Barré syndrome, other polyneuropathies, and spinal cord infarction would not be expected with these CSF features.

Surface EMG demonstrated normal sensory responses, and needle EMG showed chronic and active motor axon loss in the L3 and S1 root distributions, suggesting polyradiculopathy without polyneuropathy. These findings would not be expected in typical acute transverse myelitis but could be seen with spinal cord infarction.

MRI of the entire spine with and without contrast showed cauda equina nerve root thickening and enhancement, especially involving the L5 and S1 roots (Figure 1). The spinal cord appeared normal. These findings further supported polyradiculopathy and a leptomeningeal process.

Further evaluation included chest radiography, erythrocyte sedimentation rate, C-reactive protein, hemoglobin A_1c, human immunodeficiency virus testing, antinuclear antibody, antineutrophil cytoplasmic antibody, extractable nuclear antibody, GQ1b antibody, serum and CSF paraneoplastic panels, levels of vitamin B₁, B₁₂, and B₆, copper, and ceruloplasmin, and a screen for heavy metals. All results were within normal ranges.

ESTABLISHING THE DIAGNOSIS

Serum monoclonal protein analysis with immunofixation revealed IgM kappa monoclonal gammopathy with an IgM level of 1,570 (reference range 53–334 mg/dL) and M-spike 0.75 (0.00 mg/dL), serum free kappa light chains 61.1 (3.30–19.40 mg/L), lambda 9.3 (5.7–26.3 mg/L), and kappa-lambda ratio 6.57 (0.26–1.65).

2. Which is the best next step in this patient’s neurologic evaluation?

• Test CSF angiotensin-converting enzyme level
• CSF cytology
• Meningeal biopsy
• Peripheral nerve biopsy

Given the high suspicion for malignancy, CSF cytology was performed and showed increased numbers of mononuclear chronic inflammatory cells, including a mixture of lymphocytes and monocytes, favoring a reactive lymphoid pleocytosis. Flow cytometry indicated the presence of a monoclonal, CD5- and CD10- negative, B-cell lymphoproliferative disorder. The immunophenotypic findings were not specific for a single diagnosis. The differential diagnosis included marginal zone lymphoma and lymphoplasmacytic lymphoma.

3. Given the presence of serum IgM monoclonal gammopathy in this patient, which is the most likely diagnosis?

• Neurosarcoidosis
• Multiple myeloma
• Waldenström macroglobulinemia
• Carcinomatous meningitis

Study of bone marrow biopsy demonstrated limited bone marrow involvement (1%) by a lymphoproliferative disorder with plasmacytoid features, and DNA testing detected an MYD88 L265P mutation, reported to be present in 90% of patients with Waldenström macroglobulinemia.⁹ This finding confirmed the diagnosis of Waldenström macroglobulinemia with central nervous system involvement. Our patient began therapy with rituximab and methotrexate, which resulted in some improvement in strength, gait, and vision.

 

 

WALDENSTRÖM MACROGLOBULINEMIA AND BING-NEEL SYNDROME

Waldenström macroglobulinemia is a lympho­plasmacytic lymphoma associated with a monoclonal IgM protein.¹⁰ It is considered a paraproteinemic disorder, similar to multiple myeloma. The presenting symptoms and complications are related to direct tumor infiltration, hyperviscosity syndrome, and deposition of IgM in various tissues.^11,12

Waldenström macroglobulinemia is usually indolent, and treatment is reserved for patients with symptoms.^13,14 It includes rituximab, usually in combination with chemotherapy or other targeted agents.^15,16

Paraneoplastic antibody-mediated polyneuropathy may occur in these patients. However, the pattern is usually symmetrical clinically, with demyelination on EMG, and is not associated with cranial nerve or meningeal involvement. Management with plasmapheresis, corticosteroids, and intravenous immunoglobulin has not been shown to be effective.¹⁷

Involvement of the central nervous system as a complication of Waldenström macroglobulinemia has been described as Bing-Neel syndrome. It can present as diffuse malignant cell infiltration of the leptomeningeal space, white matter, or spinal cord, or in a tumoral form presenting as intraparenchymal masses or nodular lesions. The distinction between the tumoral and diffuse forms is based primarily on imaging findings.¹⁸

In a report of 44 patients with Bing-Neel syndrome, 36% presented with the disorder as the initial manifestation of Waldenström macroglobulinemia.¹⁸ The primary presenting symptoms were imbalance and gait difficulty (48%) and cranial nerve involvement (36%), which presented as predominantly facial or oculomotor nerve palsy. Cauda equina syndrome with motor involvement (seen in our patient) occurred in 14% of patients. Other presenting symptoms included cognitive impairment, sensory deficits, headache, dysarthria, aphasia, and seizures.

LEARNING POINTS

The differential diagnosis for patients presenting with multifocal neurologic symptoms can be broad, and a systematic approach to the diagnosis is necessary. Localizing the lesion is important in determining the diagnosis for patients presenting with neurologic symptoms. The process of localization begins with taking the history, is further refined during the examination, and is confirmed with diagnostic studies. Atypical presentations of relatively common neurologic diseases such as Guillain-Barré syndrome, transverse myelitis, and peripheral polyneuropathy do occur, but uncommon diagnoses need to be considered when support for the initial diagnosis is lacking.

A 69-year-old woman was admitted to the hospital with double vision, weakness in the lower extremities, sensory loss, pain, and falls. Her symptoms started with sudden onset of horizontal diplopia 6 weeks before, followed by gradually worsening lower-extremity weakness, as well as ataxia and patchy and bilateral radicular burning leg pain more pronounced on the right. Her medical history included narcolepsy, obstructive sleep apnea, hypertension, hyperlipidemia, and bilateral knee replacements for osteoarthritis.

Neurologic examination showed inability to abduct the right eye, bilateral hip flexion weakness, decreased pinprick response, decreased proprioception, and diminished muscle stretch reflexes in the lower extremities. Magnetic resonance imaging (MRI) of the brain without contrast and magnetic resonance angiography of the brain and carotid arteries showed no evidence of acute stroke. No abnormalities were noted on electrocardiography and echocardiography.

A diagnosis of idiopathic peripheral neuropathy was made, and outpatient physical therapy was recommended. Over the subsequent 2 weeks, her condition declined to the point where she needed a walker. She continued to have worsening leg weakness with falls, prompting hospital readmission.

INITIAL EVALUATION

In addition to her diplopia and weakness, she said she had lost 15 pounds since the onset of symptoms and had experienced symptoms suggesting urinary retention.

Physical examination

Her temperature was 37°C (98.6°F), heart rate 79 beats per minute, blood pressure 117/86 mm Hg, respiratory rate 14 breaths per minute, and oxygen saturation 98% on room air. Examination of the head, neck, heart, lung, abdomen, lymph nodes, and extremities yielded nothing remarkable except for chronic venous changes in the lower extremities.

The neurologic examination showed incomplete lateral gaze bilaterally (cranial nerve VI dysfunction). Strength in the upper extremities was normal. In the legs, the Medical Research Council scale score for proximal muscle strength was 2 to 3 out of 5, and for distal muscles 3 to 4 out of 5, with the right side worse than the left and flexors and extensors affected equally. Muscle stretch reflexes were absent in both lower extremities and the left upper extremity, but intact in the right upper extremity. No abnormal corticospinal tract reflexes were elicited.

Sensory testing revealed diminished pin-prick perception in a length-dependent fashion in the lower extremities, reduced 50% compared with the hands. Gait could not be assessed due to weakness.

Initial laboratory testing

Results of initial laboratory tests—complete blood cell count, complete metabolic panel, erythrocyte sedimentation rate, C-reactive protein, thyroid-stimulating hormone, and hemoglobin A_1c—were unremarkable.

 

 

FURTHER EVALUATION AND DIFFERENTIAL DIAGNOSIS

1. Which of the following is the most likely diagnosis at this point?

• Cerebral infarction
• Guillain-Barré syndrome
• Progressive polyneuropathy
• Transverse myelitis
• Polyradiculopathy

In the absence of definitive diagnostic tests, all of the above options were considered in the differential diagnosis for this patient.

Cerebral infarction

Although acute-onset diplopia can be explained by brainstem stroke involving cranial nerve nuclei or their projections, the onset of diplopia with progressive bilateral lower-extremity weakness makes stroke unlikely. Flaccid paralysis, areflexia of the lower extremities, and sensory involvement can also be caused by acute anterior spinal artery occlusion leading to spinal cord infarction; however, the deficits are usually maximal at onset.

Guillain-Barré syndrome

The combination of acute-subacute progressive ascending weakness, sensory involvement, and diminished or absent reflexes is typical of Guillain-Barré syndrome. Cranial nerve involvement can overlap with the more typical features of the syndrome. However, most patients reach the nadir of their disease by 4 weeks after initial symptom onset, even without treatment.¹ This patient’s condition continued to worsen over 8 weeks. In addition, the asymmetric lower-extremity weakness and sparing of the arms are atypical for Guillain-Barré syndrome.

Given the progression of symptoms, chronic inflammatory demyelinating polyneuropathy is also a consideration, typically presenting as a relapsing or progressive neuropathy in proximal and distal muscles and worsening over at least an 8-week period.²

The initial workup for Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy includes lumbar puncture to assess for albuminocytologic dissociation (elevated protein with normal white blood cell count) in cerebrospinal fluid (CSF), and electromyography (EMG) to assess for neuro­physiologic evidence of peripheral nerve demyelination. In Miller-Fisher syndrome, a rare variant of Guillain-Barré syndrome characterized by ataxia, ophthalmoparesis, and areflexia, serum ganglioside antibodies to GQ1b are found in over 90% of patients.^3,4 Although MRI of the spine is not necessary to diagnose Guillain-Barré syndrome, it is often done to exclude other causes of lower-extremity weakness such as spinal cord or cauda equina compression that would require urgent neurosurgical consultation. MRI can support the diagnosis of Guillain-Barré syndrome when it reveals enhancement of the spinal nerve roots or cauda equina.

Other polyneuropathies

Polyneuropathy is caused by a variety of diseases that affect the function of peripheral motor, sensory, or autonomic nerves. The differential diagnosis is broad and involves inflammatory diseases (including autoimmune and paraneoplastic causes), hereditary disorders, infection, toxicity, and ischemic and nutritional deficiencies.⁵ Polyneuropathy can present in a distal-predominant, generalized, or asymmetric pattern involving individual nerve trunks termed “mononeuropathy multiplex,” as in our patient’s presentation. The initial workup includes EMG and a battery of serologic tests. In cases of severe and progressive polyneuropathy, nerve biopsy can assess for the presence of vasculitis, amyloidosis, and paraprotein deposition.

Transverse myelitis

Transverse myelitis is an inflammatory myelopathy that usually presents with acute or subacute weakness of the upper extremities or lower extremities, or both, corresponding to the level of the lesion, hyperreflexia, bladder and bowel dysfunction, spinal level of sensory loss, and autonomic involvement.⁶ The differential diagnosis of acute myelopathy includes:

• Infection (eg, herpes simplex virus, West Nile virus, Lyme disease, Mycoplasma pneumoniae, human immunodeficiency virus)
• Systemic inflammatory disease (systemic lupus erythematosus, sarcoidosis, Sjögren syndrome, scleroderma, paraneoplastic syndrome)
• Central nervous system demyelinating disease (acute disseminated encephalomyelitis, multiple sclerosis, neuromyelitis optica)
• Vascular malformation (dural arteriovenous fistula)
• Compression due to tumor, bleeding, disc herniation, infection, or abscess.

The workup involves laboratory tests to exclude systemic inflammatory and infectious causes, as well as MRI of the spine with and without contrast to identify a causative lesion. Lumbar puncture and CSF analysis may show pleocytosis, elevated protein concentration, and increased intrathecal immunoglobulin G (IgG) index.⁷

Although our patient’s presentation with subacute lower-extremity weakness, sensory changes, and bladder dysfunction were consistent with transverse myelitis, her cranial nerve abnormalities would be atypical for it.

Polyradiculopathy


Polyradiculopathy has many possible causes. In the United States, the most common causes are lumbar spondylosis, lumbar canal stenosis, and diabetic polyradiculoneuropathy.

When multiple spinal segments are affected, leptomeningeal disease involving the arachnoid and pia mater should be considered. Causes include malignant invasion, inflammatory cell accumulation, and protein deposition, leading to patchy but widespread dysfunction of spinal nerve roots and cranial nerves. Specific causes are myriad and include carcinomatous meningitis,⁸ syphilis, tuberculosis, sarcoidosis, and paraproteinemias. CSF and MRI changes are often nonspecific, leading to the need for meningeal biopsy for diagnosis.

 

 

CASE CONTINUED

During her hospitalization, our patient developed acute right upper and lower facial weakness consistent with peripheral facial mononeuropathy. Bilateral lower-extremity weakness progressed to disabling paraparesis.

She underwent lumbar puncture and CSF analysis (Table 1). The most notable findings were significant pleocytosis (72% lymphocytic predominance), protein elevation, and elevated IgG index (indicative of elevated intrathecal immunoglobulin synthesis in the central nervous system). Viral, bacterial, and fungal studies were negative. Guillain-Barré syndrome, other polyneuropathies, and spinal cord infarction would not be expected with these CSF features.

Surface EMG demonstrated normal sensory responses, and needle EMG showed chronic and active motor axon loss in the L3 and S1 root distributions, suggesting polyradiculopathy without polyneuropathy. These findings would not be expected in typical acute transverse myelitis but could be seen with spinal cord infarction.

MRI of the entire spine with and without contrast showed cauda equina nerve root thickening and enhancement, especially involving the L5 and S1 roots (Figure 1). The spinal cord appeared normal. These findings further supported polyradiculopathy and a leptomeningeal process.

Further evaluation included chest radiography, erythrocyte sedimentation rate, C-reactive protein, hemoglobin A_1c, human immunodeficiency virus testing, antinuclear antibody, antineutrophil cytoplasmic antibody, extractable nuclear antibody, GQ1b antibody, serum and CSF paraneoplastic panels, levels of vitamin B₁, B₁₂, and B₆, copper, and ceruloplasmin, and a screen for heavy metals. All results were within normal ranges.

ESTABLISHING THE DIAGNOSIS

Serum monoclonal protein analysis with immunofixation revealed IgM kappa monoclonal gammopathy with an IgM level of 1,570 (reference range 53–334 mg/dL) and M-spike 0.75 (0.00 mg/dL), serum free kappa light chains 61.1 (3.30–19.40 mg/L), lambda 9.3 (5.7–26.3 mg/L), and kappa-lambda ratio 6.57 (0.26–1.65).

2. Which is the best next step in this patient’s neurologic evaluation?

• Test CSF angiotensin-converting enzyme level
• CSF cytology
• Meningeal biopsy
• Peripheral nerve biopsy

Given the high suspicion for malignancy, CSF cytology was performed and showed increased numbers of mononuclear chronic inflammatory cells, including a mixture of lymphocytes and monocytes, favoring a reactive lymphoid pleocytosis. Flow cytometry indicated the presence of a monoclonal, CD5- and CD10- negative, B-cell lymphoproliferative disorder. The immunophenotypic findings were not specific for a single diagnosis. The differential diagnosis included marginal zone lymphoma and lymphoplasmacytic lymphoma.

3. Given the presence of serum IgM monoclonal gammopathy in this patient, which is the most likely diagnosis?

• Neurosarcoidosis
• Multiple myeloma
• Waldenström macroglobulinemia
• Carcinomatous meningitis

Study of bone marrow biopsy demonstrated limited bone marrow involvement (1%) by a lymphoproliferative disorder with plasmacytoid features, and DNA testing detected an MYD88 L265P mutation, reported to be present in 90% of patients with Waldenström macroglobulinemia.⁹ This finding confirmed the diagnosis of Waldenström macroglobulinemia with central nervous system involvement. Our patient began therapy with rituximab and methotrexate, which resulted in some improvement in strength, gait, and vision.

 

 

WALDENSTRÖM MACROGLOBULINEMIA AND BING-NEEL SYNDROME

Waldenström macroglobulinemia is a lympho­plasmacytic lymphoma associated with a monoclonal IgM protein.¹⁰ It is considered a paraproteinemic disorder, similar to multiple myeloma. The presenting symptoms and complications are related to direct tumor infiltration, hyperviscosity syndrome, and deposition of IgM in various tissues.^11,12

Waldenström macroglobulinemia is usually indolent, and treatment is reserved for patients with symptoms.^13,14 It includes rituximab, usually in combination with chemotherapy or other targeted agents.^15,16

Paraneoplastic antibody-mediated polyneuropathy may occur in these patients. However, the pattern is usually symmetrical clinically, with demyelination on EMG, and is not associated with cranial nerve or meningeal involvement. Management with plasmapheresis, corticosteroids, and intravenous immunoglobulin has not been shown to be effective.¹⁷

Involvement of the central nervous system as a complication of Waldenström macroglobulinemia has been described as Bing-Neel syndrome. It can present as diffuse malignant cell infiltration of the leptomeningeal space, white matter, or spinal cord, or in a tumoral form presenting as intraparenchymal masses or nodular lesions. The distinction between the tumoral and diffuse forms is based primarily on imaging findings.¹⁸

In a report of 44 patients with Bing-Neel syndrome, 36% presented with the disorder as the initial manifestation of Waldenström macroglobulinemia.¹⁸ The primary presenting symptoms were imbalance and gait difficulty (48%) and cranial nerve involvement (36%), which presented as predominantly facial or oculomotor nerve palsy. Cauda equina syndrome with motor involvement (seen in our patient) occurred in 14% of patients. Other presenting symptoms included cognitive impairment, sensory deficits, headache, dysarthria, aphasia, and seizures.

LEARNING POINTS

The differential diagnosis for patients presenting with multifocal neurologic symptoms can be broad, and a systematic approach to the diagnosis is necessary. Localizing the lesion is important in determining the diagnosis for patients presenting with neurologic symptoms. The process of localization begins with taking the history, is further refined during the examination, and is confirmed with diagnostic studies. Atypical presentations of relatively common neurologic diseases such as Guillain-Barré syndrome, transverse myelitis, and peripheral polyneuropathy do occur, but uncommon diagnoses need to be considered when support for the initial diagnosis is lacking.

A 69-year-old woman was admitted to the hospital with double vision, weakness in the lower extremities, sensory loss, pain, and falls. Her symptoms started with sudden onset of horizontal diplopia 6 weeks before, followed by gradually worsening lower-extremity weakness, as well as ataxia and patchy and bilateral radicular burning leg pain more pronounced on the right. Her medical history included narcolepsy, obstructive sleep apnea, hypertension, hyperlipidemia, and bilateral knee replacements for osteoarthritis.

Neurologic examination showed inability to abduct the right eye, bilateral hip flexion weakness, decreased pinprick response, decreased proprioception, and diminished muscle stretch reflexes in the lower extremities. Magnetic resonance imaging (MRI) of the brain without contrast and magnetic resonance angiography of the brain and carotid arteries showed no evidence of acute stroke. No abnormalities were noted on electrocardiography and echocardiography.

A diagnosis of idiopathic peripheral neuropathy was made, and outpatient physical therapy was recommended. Over the subsequent 2 weeks, her condition declined to the point where she needed a walker. She continued to have worsening leg weakness with falls, prompting hospital readmission.

INITIAL EVALUATION

In addition to her diplopia and weakness, she said she had lost 15 pounds since the onset of symptoms and had experienced symptoms suggesting urinary retention.

Physical examination

Her temperature was 37°C (98.6°F), heart rate 79 beats per minute, blood pressure 117/86 mm Hg, respiratory rate 14 breaths per minute, and oxygen saturation 98% on room air. Examination of the head, neck, heart, lung, abdomen, lymph nodes, and extremities yielded nothing remarkable except for chronic venous changes in the lower extremities.

The neurologic examination showed incomplete lateral gaze bilaterally (cranial nerve VI dysfunction). Strength in the upper extremities was normal. In the legs, the Medical Research Council scale score for proximal muscle strength was 2 to 3 out of 5, and for distal muscles 3 to 4 out of 5, with the right side worse than the left and flexors and extensors affected equally. Muscle stretch reflexes were absent in both lower extremities and the left upper extremity, but intact in the right upper extremity. No abnormal corticospinal tract reflexes were elicited.

Sensory testing revealed diminished pin-prick perception in a length-dependent fashion in the lower extremities, reduced 50% compared with the hands. Gait could not be assessed due to weakness.

Initial laboratory testing

Results of initial laboratory tests—complete blood cell count, complete metabolic panel, erythrocyte sedimentation rate, C-reactive protein, thyroid-stimulating hormone, and hemoglobin A_1c—were unremarkable.

 

 

FURTHER EVALUATION AND DIFFERENTIAL DIAGNOSIS

1. Which of the following is the most likely diagnosis at this point?

• Cerebral infarction
• Guillain-Barré syndrome
• Progressive polyneuropathy
• Transverse myelitis
• Polyradiculopathy

In the absence of definitive diagnostic tests, all of the above options were considered in the differential diagnosis for this patient.

Cerebral infarction

Although acute-onset diplopia can be explained by brainstem stroke involving cranial nerve nuclei or their projections, the onset of diplopia with progressive bilateral lower-extremity weakness makes stroke unlikely. Flaccid paralysis, areflexia of the lower extremities, and sensory involvement can also be caused by acute anterior spinal artery occlusion leading to spinal cord infarction; however, the deficits are usually maximal at onset.

Guillain-Barré syndrome

The combination of acute-subacute progressive ascending weakness, sensory involvement, and diminished or absent reflexes is typical of Guillain-Barré syndrome. Cranial nerve involvement can overlap with the more typical features of the syndrome. However, most patients reach the nadir of their disease by 4 weeks after initial symptom onset, even without treatment.¹ This patient’s condition continued to worsen over 8 weeks. In addition, the asymmetric lower-extremity weakness and sparing of the arms are atypical for Guillain-Barré syndrome.

Given the progression of symptoms, chronic inflammatory demyelinating polyneuropathy is also a consideration, typically presenting as a relapsing or progressive neuropathy in proximal and distal muscles and worsening over at least an 8-week period.²

The initial workup for Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy includes lumbar puncture to assess for albuminocytologic dissociation (elevated protein with normal white blood cell count) in cerebrospinal fluid (CSF), and electromyography (EMG) to assess for neuro­physiologic evidence of peripheral nerve demyelination. In Miller-Fisher syndrome, a rare variant of Guillain-Barré syndrome characterized by ataxia, ophthalmoparesis, and areflexia, serum ganglioside antibodies to GQ1b are found in over 90% of patients.^3,4 Although MRI of the spine is not necessary to diagnose Guillain-Barré syndrome, it is often done to exclude other causes of lower-extremity weakness such as spinal cord or cauda equina compression that would require urgent neurosurgical consultation. MRI can support the diagnosis of Guillain-Barré syndrome when it reveals enhancement of the spinal nerve roots or cauda equina.

Other polyneuropathies

Polyneuropathy is caused by a variety of diseases that affect the function of peripheral motor, sensory, or autonomic nerves. The differential diagnosis is broad and involves inflammatory diseases (including autoimmune and paraneoplastic causes), hereditary disorders, infection, toxicity, and ischemic and nutritional deficiencies.⁵ Polyneuropathy can present in a distal-predominant, generalized, or asymmetric pattern involving individual nerve trunks termed “mononeuropathy multiplex,” as in our patient’s presentation. The initial workup includes EMG and a battery of serologic tests. In cases of severe and progressive polyneuropathy, nerve biopsy can assess for the presence of vasculitis, amyloidosis, and paraprotein deposition.

Transverse myelitis

Transverse myelitis is an inflammatory myelopathy that usually presents with acute or subacute weakness of the upper extremities or lower extremities, or both, corresponding to the level of the lesion, hyperreflexia, bladder and bowel dysfunction, spinal level of sensory loss, and autonomic involvement.⁶ The differential diagnosis of acute myelopathy includes:

• Infection (eg, herpes simplex virus, West Nile virus, Lyme disease, Mycoplasma pneumoniae, human immunodeficiency virus)
• Systemic inflammatory disease (systemic lupus erythematosus, sarcoidosis, Sjögren syndrome, scleroderma, paraneoplastic syndrome)
• Central nervous system demyelinating disease (acute disseminated encephalomyelitis, multiple sclerosis, neuromyelitis optica)
• Vascular malformation (dural arteriovenous fistula)
• Compression due to tumor, bleeding, disc herniation, infection, or abscess.

The workup involves laboratory tests to exclude systemic inflammatory and infectious causes, as well as MRI of the spine with and without contrast to identify a causative lesion. Lumbar puncture and CSF analysis may show pleocytosis, elevated protein concentration, and increased intrathecal immunoglobulin G (IgG) index.⁷

Although our patient’s presentation with subacute lower-extremity weakness, sensory changes, and bladder dysfunction were consistent with transverse myelitis, her cranial nerve abnormalities would be atypical for it.

Polyradiculopathy


Polyradiculopathy has many possible causes. In the United States, the most common causes are lumbar spondylosis, lumbar canal stenosis, and diabetic polyradiculoneuropathy.

When multiple spinal segments are affected, leptomeningeal disease involving the arachnoid and pia mater should be considered. Causes include malignant invasion, inflammatory cell accumulation, and protein deposition, leading to patchy but widespread dysfunction of spinal nerve roots and cranial nerves. Specific causes are myriad and include carcinomatous meningitis,⁸ syphilis, tuberculosis, sarcoidosis, and paraproteinemias. CSF and MRI changes are often nonspecific, leading to the need for meningeal biopsy for diagnosis.

 

 

CASE CONTINUED

During her hospitalization, our patient developed acute right upper and lower facial weakness consistent with peripheral facial mononeuropathy. Bilateral lower-extremity weakness progressed to disabling paraparesis.

She underwent lumbar puncture and CSF analysis (Table 1). The most notable findings were significant pleocytosis (72% lymphocytic predominance), protein elevation, and elevated IgG index (indicative of elevated intrathecal immunoglobulin synthesis in the central nervous system). Viral, bacterial, and fungal studies were negative. Guillain-Barré syndrome, other polyneuropathies, and spinal cord infarction would not be expected with these CSF features.

Surface EMG demonstrated normal sensory responses, and needle EMG showed chronic and active motor axon loss in the L3 and S1 root distributions, suggesting polyradiculopathy without polyneuropathy. These findings would not be expected in typical acute transverse myelitis but could be seen with spinal cord infarction.

MRI of the entire spine with and without contrast showed cauda equina nerve root thickening and enhancement, especially involving the L5 and S1 roots (Figure 1). The spinal cord appeared normal. These findings further supported polyradiculopathy and a leptomeningeal process.

Further evaluation included chest radiography, erythrocyte sedimentation rate, C-reactive protein, hemoglobin A_1c, human immunodeficiency virus testing, antinuclear antibody, antineutrophil cytoplasmic antibody, extractable nuclear antibody, GQ1b antibody, serum and CSF paraneoplastic panels, levels of vitamin B₁, B₁₂, and B₆, copper, and ceruloplasmin, and a screen for heavy metals. All results were within normal ranges.

ESTABLISHING THE DIAGNOSIS

Serum monoclonal protein analysis with immunofixation revealed IgM kappa monoclonal gammopathy with an IgM level of 1,570 (reference range 53–334 mg/dL) and M-spike 0.75 (0.00 mg/dL), serum free kappa light chains 61.1 (3.30–19.40 mg/L), lambda 9.3 (5.7–26.3 mg/L), and kappa-lambda ratio 6.57 (0.26–1.65).

2. Which is the best next step in this patient’s neurologic evaluation?

• Test CSF angiotensin-converting enzyme level
• CSF cytology
• Meningeal biopsy
• Peripheral nerve biopsy

Given the high suspicion for malignancy, CSF cytology was performed and showed increased numbers of mononuclear chronic inflammatory cells, including a mixture of lymphocytes and monocytes, favoring a reactive lymphoid pleocytosis. Flow cytometry indicated the presence of a monoclonal, CD5- and CD10- negative, B-cell lymphoproliferative disorder. The immunophenotypic findings were not specific for a single diagnosis. The differential diagnosis included marginal zone lymphoma and lymphoplasmacytic lymphoma.

3. Given the presence of serum IgM monoclonal gammopathy in this patient, which is the most likely diagnosis?

• Neurosarcoidosis
• Multiple myeloma
• Waldenström macroglobulinemia
• Carcinomatous meningitis

Study of bone marrow biopsy demonstrated limited bone marrow involvement (1%) by a lymphoproliferative disorder with plasmacytoid features, and DNA testing detected an MYD88 L265P mutation, reported to be present in 90% of patients with Waldenström macroglobulinemia.⁹ This finding confirmed the diagnosis of Waldenström macroglobulinemia with central nervous system involvement. Our patient began therapy with rituximab and methotrexate, which resulted in some improvement in strength, gait, and vision.

 

 

WALDENSTRÖM MACROGLOBULINEMIA AND BING-NEEL SYNDROME

Waldenström macroglobulinemia is a lympho­plasmacytic lymphoma associated with a monoclonal IgM protein.¹⁰ It is considered a paraproteinemic disorder, similar to multiple myeloma. The presenting symptoms and complications are related to direct tumor infiltration, hyperviscosity syndrome, and deposition of IgM in various tissues.^11,12

Waldenström macroglobulinemia is usually indolent, and treatment is reserved for patients with symptoms.^13,14 It includes rituximab, usually in combination with chemotherapy or other targeted agents.^15,16

Paraneoplastic antibody-mediated polyneuropathy may occur in these patients. However, the pattern is usually symmetrical clinically, with demyelination on EMG, and is not associated with cranial nerve or meningeal involvement. Management with plasmapheresis, corticosteroids, and intravenous immunoglobulin has not been shown to be effective.¹⁷

Involvement of the central nervous system as a complication of Waldenström macroglobulinemia has been described as Bing-Neel syndrome. It can present as diffuse malignant cell infiltration of the leptomeningeal space, white matter, or spinal cord, or in a tumoral form presenting as intraparenchymal masses or nodular lesions. The distinction between the tumoral and diffuse forms is based primarily on imaging findings.¹⁸

In a report of 44 patients with Bing-Neel syndrome, 36% presented with the disorder as the initial manifestation of Waldenström macroglobulinemia.¹⁸ The primary presenting symptoms were imbalance and gait difficulty (48%) and cranial nerve involvement (36%), which presented as predominantly facial or oculomotor nerve palsy. Cauda equina syndrome with motor involvement (seen in our patient) occurred in 14% of patients. Other presenting symptoms included cognitive impairment, sensory deficits, headache, dysarthria, aphasia, and seizures.

LEARNING POINTS

The differential diagnosis for patients presenting with multifocal neurologic symptoms can be broad, and a systematic approach to the diagnosis is necessary. Localizing the lesion is important in determining the diagnosis for patients presenting with neurologic symptoms. The process of localization begins with taking the history, is further refined during the examination, and is confirmed with diagnostic studies. Atypical presentations of relatively common neurologic diseases such as Guillain-Barré syndrome, transverse myelitis, and peripheral polyneuropathy do occur, but uncommon diagnoses need to be considered when support for the initial diagnosis is lacking.

To the Editor: The review by May et al¹ of 3 neglected numbers in the complete blood cell count (CBC) was a good reminder to look more closely at the results of the CBCs we often order in primary care. I was surprised to see no mention of the red cell distribution width in relation to another cardiovascular disorder—obstructive sleep apnea.^2,3 I wonder if the authors would comment on this association?

To the Editor: The review by May et al¹ of 3 neglected numbers in the complete blood cell count (CBC) was a good reminder to look more closely at the results of the CBCs we often order in primary care. I was surprised to see no mention of the red cell distribution width in relation to another cardiovascular disorder—obstructive sleep apnea.^2,3 I wonder if the authors would comment on this association?

To the Editor: The review by May et al¹ of 3 neglected numbers in the complete blood cell count (CBC) was a good reminder to look more closely at the results of the CBCs we often order in primary care. I was surprised to see no mention of the red cell distribution width in relation to another cardiovascular disorder—obstructive sleep apnea.^2,3 I wonder if the authors would comment on this association?

In Reply: We thank Dr. Homler for his question and for highlighting another important disease state, obstructive sleep apnea, in which a high red cell distribution width (RDW) has correlated with disease severity.^1,2 The 2 retrospective studies he mentioned indicated that RDW is negatively correlated with metrics such as oxygen saturation, sleep time, and sleep quality. Interestingly, another retrospective study showed that RDW was significantly higher in patients with concurrent obstructive sleep apnea and cardiovascular disease than in patients with obstructive sleep apnea alone, suggesting that the presence of anisocytosis in obstructive sleep apnea may be due to its link to cardiovascular disease.³

Although we focused on cardiovascular disease in our review, RDW has also shown prognostic significance in many other disorders including ischemic stroke,⁴ pneumonia,^5,6 chronic kidney disease,⁷ and gastrointestinal disorders.⁸ Collectively, these studies indicate that RDW may serve as a red flag for clinicians, raising concern for increased disease severity and potential adverse outcomes. However, further research is needed to determine if and how RDW monitoring should be used to prompt interventions to improve patient outcomes.

In Reply: We thank Dr. Homler for his question and for highlighting another important disease state, obstructive sleep apnea, in which a high red cell distribution width (RDW) has correlated with disease severity.^1,2 The 2 retrospective studies he mentioned indicated that RDW is negatively correlated with metrics such as oxygen saturation, sleep time, and sleep quality. Interestingly, another retrospective study showed that RDW was significantly higher in patients with concurrent obstructive sleep apnea and cardiovascular disease than in patients with obstructive sleep apnea alone, suggesting that the presence of anisocytosis in obstructive sleep apnea may be due to its link to cardiovascular disease.³

Although we focused on cardiovascular disease in our review, RDW has also shown prognostic significance in many other disorders including ischemic stroke,⁴ pneumonia,^5,6 chronic kidney disease,⁷ and gastrointestinal disorders.⁸ Collectively, these studies indicate that RDW may serve as a red flag for clinicians, raising concern for increased disease severity and potential adverse outcomes. However, further research is needed to determine if and how RDW monitoring should be used to prompt interventions to improve patient outcomes.

In Reply: We thank Dr. Homler for his question and for highlighting another important disease state, obstructive sleep apnea, in which a high red cell distribution width (RDW) has correlated with disease severity.^1,2 The 2 retrospective studies he mentioned indicated that RDW is negatively correlated with metrics such as oxygen saturation, sleep time, and sleep quality. Interestingly, another retrospective study showed that RDW was significantly higher in patients with concurrent obstructive sleep apnea and cardiovascular disease than in patients with obstructive sleep apnea alone, suggesting that the presence of anisocytosis in obstructive sleep apnea may be due to its link to cardiovascular disease.³

Although we focused on cardiovascular disease in our review, RDW has also shown prognostic significance in many other disorders including ischemic stroke,⁴ pneumonia,^5,6 chronic kidney disease,⁷ and gastrointestinal disorders.⁸ Collectively, these studies indicate that RDW may serve as a red flag for clinicians, raising concern for increased disease severity and potential adverse outcomes. However, further research is needed to determine if and how RDW monitoring should be used to prompt interventions to improve patient outcomes.

In Azim S, Nasr C, “Subclinical hypothyroidism: When to treat,” Cleve Clin J Med 2019; 86(2):101–110, on page 103, in the section “Subclinical hypothyroidism can resolve or progress,” the sentence “The rate of progression to overt hypothyroidism is estimated to be 33% to 35% over 10 to 20 years of follow-up” contained an error. The correct rate of progression is 33% to 55%. This error has been corrected online.

In Azim S, Nasr C, “Subclinical hypothyroidism: When to treat,” Cleve Clin J Med 2019; 86(2):101–110, on page 103, in the section “Subclinical hypothyroidism can resolve or progress,” the sentence “The rate of progression to overt hypothyroidism is estimated to be 33% to 35% over 10 to 20 years of follow-up” contained an error. The correct rate of progression is 33% to 55%. This error has been corrected online.

In Azim S, Nasr C, “Subclinical hypothyroidism: When to treat,” Cleve Clin J Med 2019; 86(2):101–110, on page 103, in the section “Subclinical hypothyroidism can resolve or progress,” the sentence “The rate of progression to overt hypothyroidism is estimated to be 33% to 35% over 10 to 20 years of follow-up” contained an error. The correct rate of progression is 33% to 55%. This error has been corrected online.