User login
Patients with a baseline DLCO (diffusing capacity for carbon monoxide) of < 60% of predicted have more severe disease clinical expression with higher mortality risk, according to a long-term observational study of Global Initiative for Obstructive Lung Disease (GOLD) I chronic obstructive pulmonary disease (COPD) patients. Clarifying mechanisms of low DLCO may help clinicians direct interventions toward ameliorating the low capacity, Juan Pablo de Torres, MD, and colleagues wrote in the journal CHEST®.
Defining increased risk
“Can a DLCO threshold help define an increased risk of death and a different clinical presentation in GOLD I patients?” the researchers questioned. For evaluation of COPD, the GOLD does not currently promote the use of DLCO, and the clinical and prognostic utility of a low DLCO has not been studied, the authors noted.
Several COPD studies, however, have shown associations between low DLCO values and reduced exercise capacity, increased symptoms, risk of severe exacerbations, and mortality. The patients included in these studies, however, have generally had moderate to severe airflow limitation, and have not had postbronchodilator forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) < 0.70 and an FEV1 ≥ 80%, defined by GOLD as COPD spirometric stage I. These mild obstruction GOLD I patients, in large epidemiological studies, do have increased risk of death. But it is often assumed, Dr. de Torres and colleagues noted, that “mild” suggests a good prognosis. They propose that a simple DLCO measurement could help identify those GOLD I patients with “worse overall COPD compromise and an increased risk of death.” Importantly, GOLD I represents the largest percentage of patients with airflow limitation that epidemiological studies have identified.
The researchers enrolled 360 GOLD stage I COPD patients, recording their age, sex, pack-years’ history, body mass index, dyspnea, lung function measurements, exercise capacity, BODE (body mass index, airflow obstruction, dyspnea, and exercise capacity) index, and history of exacerbations, and followed them for a mean of 109 months. They identified a cutoff DLCO value for all-cause mortality, compared the clinical and physiological characteristics of patients above and below the threshold, and explored the predictive power of that cutoff value.
All-cause mortality difference
The mean age in the overall population studied was 63 years (31% were women), with 43% active smokers, and pack-years history of 45. Overall mortality was 11% during the follow-up period. The predominantly male population was mildly overweight, had few comorbidities, normal FEV1 values, mild dyspnea, normal 6-minute walk distance, and very few exacerbations.
Analysis showed a DLCO cutoff value of < 60% was associated with a significant all-cause mortality differential (DLCO ≥ 60%: 9% vs. DLCO < 60%: 23%, P = .01). At a same FEV1% predicted and Charlson score, patients with DLCO < 60% had lower BMI, more dyspnea, lower inspiratory capacity (IC)/total lung capacity (TLC) ratio, lower 6-minute walk distance, and higher BODE index. Adjusted Cox multiple regression analysis confirmed that a DLCO < 60% was associated with an all-cause mortality hazard ratio [HR] of 3.37, (95% confidence interval, 1.35-8.39; P = .009).
Multiorgan loss of tissue
The researchers found that patients with baseline DLCO < 60% were more likely to be women (46% versus 28%), and to have a lower BMI (25 vs. 27), higher pack-year history (54 vs. 43), the same spirometric values but lower IC/TLC ratio (.37 vs. .40), a lower walk distance (443 vs. 485 meters), higher dyspnea (MRC score 1.1 vs. .7), similar exacerbation rate, higher BODE index (.5 vs. .2) and higher mortality than patients with higher DLCO % predicted values. This group, Dr. de Torres and colleagues suggest, represents a multiorgan loss of tissue, a phenotype associated with worse clinical outcomes and prognosis.
“Low DLCO in these patients,” Dr. de Torres said in an interview, “could mainly be secondary to coexistent emphysema, which is the most common cause of low DLCO in this population. Also possible, but less likely, is coexistent pulmonary hypertension.” He noted further that “This study opens the door to research specifically testing if such is the case, and if it is, for clinicians to use available therapies to prevent adverse outcomes.”
Comorbidity burden
Patients with GOLD I COPD die more often of cardiovascular disease instead of underlying lung disease, according to Richard H. Zou, MD, and Jessica Bon, MD, of the University of Pittsburgh, in an accompanying editorial in the journal CHEST.
Increased mortality rates, they suggest, may be related to higher comorbidity burden, particularly comorbidities associated with cardiovascular-related health. Subclinical cardiovascular disease is a common comorbidity in COPD, and concomitant endothelial dysfunction has been associated with both cardiovascular disease and early emphysema in smokers. They may have disproportionately reduced DLCO levels because of parenchymal destruction.
“This study suggests that DLCO can be used to identify patients with GOLD I COPD at increased death risk and that individuals with mild airflow obstruction with DLCO <60% predicted are a clinical phenotype distinct from those with higher DLCO levels,” Dr. Zhou and Dr. Bon concluded.
The researchers and the editorialists declared that they had no disclosures. One of the three cohorts assessed in the current study (CHAIN cohort in Spain) received funding from AstraZeneca.
Patients with a baseline DLCO (diffusing capacity for carbon monoxide) of < 60% of predicted have more severe disease clinical expression with higher mortality risk, according to a long-term observational study of Global Initiative for Obstructive Lung Disease (GOLD) I chronic obstructive pulmonary disease (COPD) patients. Clarifying mechanisms of low DLCO may help clinicians direct interventions toward ameliorating the low capacity, Juan Pablo de Torres, MD, and colleagues wrote in the journal CHEST®.
Defining increased risk
“Can a DLCO threshold help define an increased risk of death and a different clinical presentation in GOLD I patients?” the researchers questioned. For evaluation of COPD, the GOLD does not currently promote the use of DLCO, and the clinical and prognostic utility of a low DLCO has not been studied, the authors noted.
Several COPD studies, however, have shown associations between low DLCO values and reduced exercise capacity, increased symptoms, risk of severe exacerbations, and mortality. The patients included in these studies, however, have generally had moderate to severe airflow limitation, and have not had postbronchodilator forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) < 0.70 and an FEV1 ≥ 80%, defined by GOLD as COPD spirometric stage I. These mild obstruction GOLD I patients, in large epidemiological studies, do have increased risk of death. But it is often assumed, Dr. de Torres and colleagues noted, that “mild” suggests a good prognosis. They propose that a simple DLCO measurement could help identify those GOLD I patients with “worse overall COPD compromise and an increased risk of death.” Importantly, GOLD I represents the largest percentage of patients with airflow limitation that epidemiological studies have identified.
The researchers enrolled 360 GOLD stage I COPD patients, recording their age, sex, pack-years’ history, body mass index, dyspnea, lung function measurements, exercise capacity, BODE (body mass index, airflow obstruction, dyspnea, and exercise capacity) index, and history of exacerbations, and followed them for a mean of 109 months. They identified a cutoff DLCO value for all-cause mortality, compared the clinical and physiological characteristics of patients above and below the threshold, and explored the predictive power of that cutoff value.
All-cause mortality difference
The mean age in the overall population studied was 63 years (31% were women), with 43% active smokers, and pack-years history of 45. Overall mortality was 11% during the follow-up period. The predominantly male population was mildly overweight, had few comorbidities, normal FEV1 values, mild dyspnea, normal 6-minute walk distance, and very few exacerbations.
Analysis showed a DLCO cutoff value of < 60% was associated with a significant all-cause mortality differential (DLCO ≥ 60%: 9% vs. DLCO < 60%: 23%, P = .01). At a same FEV1% predicted and Charlson score, patients with DLCO < 60% had lower BMI, more dyspnea, lower inspiratory capacity (IC)/total lung capacity (TLC) ratio, lower 6-minute walk distance, and higher BODE index. Adjusted Cox multiple regression analysis confirmed that a DLCO < 60% was associated with an all-cause mortality hazard ratio [HR] of 3.37, (95% confidence interval, 1.35-8.39; P = .009).
Multiorgan loss of tissue
The researchers found that patients with baseline DLCO < 60% were more likely to be women (46% versus 28%), and to have a lower BMI (25 vs. 27), higher pack-year history (54 vs. 43), the same spirometric values but lower IC/TLC ratio (.37 vs. .40), a lower walk distance (443 vs. 485 meters), higher dyspnea (MRC score 1.1 vs. .7), similar exacerbation rate, higher BODE index (.5 vs. .2) and higher mortality than patients with higher DLCO % predicted values. This group, Dr. de Torres and colleagues suggest, represents a multiorgan loss of tissue, a phenotype associated with worse clinical outcomes and prognosis.
“Low DLCO in these patients,” Dr. de Torres said in an interview, “could mainly be secondary to coexistent emphysema, which is the most common cause of low DLCO in this population. Also possible, but less likely, is coexistent pulmonary hypertension.” He noted further that “This study opens the door to research specifically testing if such is the case, and if it is, for clinicians to use available therapies to prevent adverse outcomes.”
Comorbidity burden
Patients with GOLD I COPD die more often of cardiovascular disease instead of underlying lung disease, according to Richard H. Zou, MD, and Jessica Bon, MD, of the University of Pittsburgh, in an accompanying editorial in the journal CHEST.
Increased mortality rates, they suggest, may be related to higher comorbidity burden, particularly comorbidities associated with cardiovascular-related health. Subclinical cardiovascular disease is a common comorbidity in COPD, and concomitant endothelial dysfunction has been associated with both cardiovascular disease and early emphysema in smokers. They may have disproportionately reduced DLCO levels because of parenchymal destruction.
“This study suggests that DLCO can be used to identify patients with GOLD I COPD at increased death risk and that individuals with mild airflow obstruction with DLCO <60% predicted are a clinical phenotype distinct from those with higher DLCO levels,” Dr. Zhou and Dr. Bon concluded.
The researchers and the editorialists declared that they had no disclosures. One of the three cohorts assessed in the current study (CHAIN cohort in Spain) received funding from AstraZeneca.
Patients with a baseline DLCO (diffusing capacity for carbon monoxide) of < 60% of predicted have more severe disease clinical expression with higher mortality risk, according to a long-term observational study of Global Initiative for Obstructive Lung Disease (GOLD) I chronic obstructive pulmonary disease (COPD) patients. Clarifying mechanisms of low DLCO may help clinicians direct interventions toward ameliorating the low capacity, Juan Pablo de Torres, MD, and colleagues wrote in the journal CHEST®.
Defining increased risk
“Can a DLCO threshold help define an increased risk of death and a different clinical presentation in GOLD I patients?” the researchers questioned. For evaluation of COPD, the GOLD does not currently promote the use of DLCO, and the clinical and prognostic utility of a low DLCO has not been studied, the authors noted.
Several COPD studies, however, have shown associations between low DLCO values and reduced exercise capacity, increased symptoms, risk of severe exacerbations, and mortality. The patients included in these studies, however, have generally had moderate to severe airflow limitation, and have not had postbronchodilator forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) < 0.70 and an FEV1 ≥ 80%, defined by GOLD as COPD spirometric stage I. These mild obstruction GOLD I patients, in large epidemiological studies, do have increased risk of death. But it is often assumed, Dr. de Torres and colleagues noted, that “mild” suggests a good prognosis. They propose that a simple DLCO measurement could help identify those GOLD I patients with “worse overall COPD compromise and an increased risk of death.” Importantly, GOLD I represents the largest percentage of patients with airflow limitation that epidemiological studies have identified.
The researchers enrolled 360 GOLD stage I COPD patients, recording their age, sex, pack-years’ history, body mass index, dyspnea, lung function measurements, exercise capacity, BODE (body mass index, airflow obstruction, dyspnea, and exercise capacity) index, and history of exacerbations, and followed them for a mean of 109 months. They identified a cutoff DLCO value for all-cause mortality, compared the clinical and physiological characteristics of patients above and below the threshold, and explored the predictive power of that cutoff value.
All-cause mortality difference
The mean age in the overall population studied was 63 years (31% were women), with 43% active smokers, and pack-years history of 45. Overall mortality was 11% during the follow-up period. The predominantly male population was mildly overweight, had few comorbidities, normal FEV1 values, mild dyspnea, normal 6-minute walk distance, and very few exacerbations.
Analysis showed a DLCO cutoff value of < 60% was associated with a significant all-cause mortality differential (DLCO ≥ 60%: 9% vs. DLCO < 60%: 23%, P = .01). At a same FEV1% predicted and Charlson score, patients with DLCO < 60% had lower BMI, more dyspnea, lower inspiratory capacity (IC)/total lung capacity (TLC) ratio, lower 6-minute walk distance, and higher BODE index. Adjusted Cox multiple regression analysis confirmed that a DLCO < 60% was associated with an all-cause mortality hazard ratio [HR] of 3.37, (95% confidence interval, 1.35-8.39; P = .009).
Multiorgan loss of tissue
The researchers found that patients with baseline DLCO < 60% were more likely to be women (46% versus 28%), and to have a lower BMI (25 vs. 27), higher pack-year history (54 vs. 43), the same spirometric values but lower IC/TLC ratio (.37 vs. .40), a lower walk distance (443 vs. 485 meters), higher dyspnea (MRC score 1.1 vs. .7), similar exacerbation rate, higher BODE index (.5 vs. .2) and higher mortality than patients with higher DLCO % predicted values. This group, Dr. de Torres and colleagues suggest, represents a multiorgan loss of tissue, a phenotype associated with worse clinical outcomes and prognosis.
“Low DLCO in these patients,” Dr. de Torres said in an interview, “could mainly be secondary to coexistent emphysema, which is the most common cause of low DLCO in this population. Also possible, but less likely, is coexistent pulmonary hypertension.” He noted further that “This study opens the door to research specifically testing if such is the case, and if it is, for clinicians to use available therapies to prevent adverse outcomes.”
Comorbidity burden
Patients with GOLD I COPD die more often of cardiovascular disease instead of underlying lung disease, according to Richard H. Zou, MD, and Jessica Bon, MD, of the University of Pittsburgh, in an accompanying editorial in the journal CHEST.
Increased mortality rates, they suggest, may be related to higher comorbidity burden, particularly comorbidities associated with cardiovascular-related health. Subclinical cardiovascular disease is a common comorbidity in COPD, and concomitant endothelial dysfunction has been associated with both cardiovascular disease and early emphysema in smokers. They may have disproportionately reduced DLCO levels because of parenchymal destruction.
“This study suggests that DLCO can be used to identify patients with GOLD I COPD at increased death risk and that individuals with mild airflow obstruction with DLCO <60% predicted are a clinical phenotype distinct from those with higher DLCO levels,” Dr. Zhou and Dr. Bon concluded.
The researchers and the editorialists declared that they had no disclosures. One of the three cohorts assessed in the current study (CHAIN cohort in Spain) received funding from AstraZeneca.
FROM THE JOURNAL CHEST®