Aspirin Reduces Recurrence of Vascular Events and VTEs

A 100-mg daily dose of aspirin reduced by one-third the rate of recurrent major vascular events for patients who had one acute unprovoked venous thromboembolism and were switched from anticoagulant therapy to either aspirin or placebo after 3 months of anticoagulant therapy.*

Patients with one episode of unprovoked VTE often discontinue anticoagulant therapy due to inconvenience and the risk of bleeding, said Dr. Timothy A. Brighton of the University of Sydney, Australia, and his colleagues. For those patients, 100 mg of aspirin per day appears to be a safe alternative.

Dr. Brighton and his colleagues reported the findings based on combined data from the ASPIRE (Aspirin to Prevent Recurrent Venous Thromboembolism) study and the WARFASA (Warfarin and Aspirin) study. The findings of ASPIRE were simultaneously published in the New England Journal of Medicine and presented at the annual meeting of the American Heart Association in Los Angeles. The findings of WARFASA were previously published in the same journal.

ASPIRE examined the effect of a 100-mg daily dose of aspirin in patients who had a history of a first-ever unprovoked VTE and had completed initial anticoagulation therapy. The study population included 822 adults who were randomized to a placebo or aspirin at 56 sites in five countries from May 2003 and August 2011. Roughly half of the patients were men; 56% had a proximal deep-vein thrombosis as an index event; 29% had a pulmonary embolism as an index event, and 14% had both conditions as an index event (N. Engl. J. Med. 2012 Nov. 4 [doi: 10.1056/NEJMoa1210384]).

Overall, VTE recurred in 57 patients (14%) in the aspirin group, compared with 73 patients (18%) in the placebo group (rates of 5% and 7% per year, respectively, a nonsignificant difference).

However, the rates of two secondary composite outcomes were significantly reduced in patients who took aspirin compared with those on placebo, the researchers noted. The rate of a composite outcome including VTE, myocardial infarction, stroke, or cardiovascular death was reduced by 34% in aspirin patients (5% per year for aspirin vs. 8% per year for placebo).

The rate of a composite outcome including VTE, myocardial infarction, stroke, major bleeding, or death from any cause was reduce by 33% in aspirin patients (6% per year for aspirin vs. 9% per year for placebo).

No significant differences in serious adverse events or in the rates of major or clinically relevant nonmajor bleeding were observed between the aspirin and placebo groups, the researchers noted.

The findings were limited by the low number of patients in the study, however. The ASPIRE data alone were not adequately powered to show a significant reduction in the recurrence of VTE.

To address the issue, researchers combined the ASPIRE data with data from a similar population of 402 patients in the WARFASA (Warfarin and Aspirin) study (N. Engl. J. Med. 2012; 366:1959-67). In this multicenter, double-blind study, patients with first-ever unprovoked venous thromboembolism completed 6-18 months of oral anticoagulant treatment and were randomly assigned to aspirin, 100 mg daily, or placebo for 2 years.

VTE recurred in 28 of the 205 patients who received aspirin and in 43 of the 197 patients who received placebo (6.6% vs. 11.2% per year; hazard ratio, 0.58; 95% confidence interval [CI], 0.36 – 0.93). One patient in each treatment group had a major bleeding episode. Adverse events were similar in the two groups.

Using the combined data from both studies, the researchers found “a highly significant reduction of 32% in the rate of recurrence of venous thromboembolism and a reduction of 34% in the rate of major vascular events with no excess of bleeding.”

Therefore, the combined results of the two studies support the use of low-dose aspirin to prevent both recurrent VTE and major vascular events in patients who have had a first episode of unprovoked VTE, the researchers said.

Lead author Dr. Brighton disclosed serving as a consultant for Pfizer, GlaxoSmithKline, and other companies. The study was supported by grants from the National Health and Medical Research Council (Australia), the Health Research Council (New Zealand), the National Heart Foundation of Australia, Bayer HealthCare (Germany), and the Australasian Society of Haematology and Thrombosis

* This story was updated on 11/7/12.

A 100-mg daily dose of aspirin reduced by one-third the rate of recurrent major vascular events for patients who had one acute unprovoked venous thromboembolism and were switched from anticoagulant therapy to either aspirin or placebo after 3 months of anticoagulant therapy.*

Patients with one episode of unprovoked VTE often discontinue anticoagulant therapy due to inconvenience and the risk of bleeding, said Dr. Timothy A. Brighton of the University of Sydney, Australia, and his colleagues. For those patients, 100 mg of aspirin per day appears to be a safe alternative.

Dr. Brighton and his colleagues reported the findings based on combined data from the ASPIRE (Aspirin to Prevent Recurrent Venous Thromboembolism) study and the WARFASA (Warfarin and Aspirin) study. The findings of ASPIRE were simultaneously published in the New England Journal of Medicine and presented at the annual meeting of the American Heart Association in Los Angeles. The findings of WARFASA were previously published in the same journal.

ASPIRE examined the effect of a 100-mg daily dose of aspirin in patients who had a history of a first-ever unprovoked VTE and had completed initial anticoagulation therapy. The study population included 822 adults who were randomized to a placebo or aspirin at 56 sites in five countries from May 2003 and August 2011. Roughly half of the patients were men; 56% had a proximal deep-vein thrombosis as an index event; 29% had a pulmonary embolism as an index event, and 14% had both conditions as an index event (N. Engl. J. Med. 2012 Nov. 4 [doi: 10.1056/NEJMoa1210384]).

Overall, VTE recurred in 57 patients (14%) in the aspirin group, compared with 73 patients (18%) in the placebo group (rates of 5% and 7% per year, respectively, a nonsignificant difference).

However, the rates of two secondary composite outcomes were significantly reduced in patients who took aspirin compared with those on placebo, the researchers noted. The rate of a composite outcome including VTE, myocardial infarction, stroke, or cardiovascular death was reduced by 34% in aspirin patients (5% per year for aspirin vs. 8% per year for placebo).

The rate of a composite outcome including VTE, myocardial infarction, stroke, major bleeding, or death from any cause was reduce by 33% in aspirin patients (6% per year for aspirin vs. 9% per year for placebo).

No significant differences in serious adverse events or in the rates of major or clinically relevant nonmajor bleeding were observed between the aspirin and placebo groups, the researchers noted.

The findings were limited by the low number of patients in the study, however. The ASPIRE data alone were not adequately powered to show a significant reduction in the recurrence of VTE.

To address the issue, researchers combined the ASPIRE data with data from a similar population of 402 patients in the WARFASA (Warfarin and Aspirin) study (N. Engl. J. Med. 2012; 366:1959-67). In this multicenter, double-blind study, patients with first-ever unprovoked venous thromboembolism completed 6-18 months of oral anticoagulant treatment and were randomly assigned to aspirin, 100 mg daily, or placebo for 2 years.

VTE recurred in 28 of the 205 patients who received aspirin and in 43 of the 197 patients who received placebo (6.6% vs. 11.2% per year; hazard ratio, 0.58; 95% confidence interval [CI], 0.36 – 0.93). One patient in each treatment group had a major bleeding episode. Adverse events were similar in the two groups.

Using the combined data from both studies, the researchers found “a highly significant reduction of 32% in the rate of recurrence of venous thromboembolism and a reduction of 34% in the rate of major vascular events with no excess of bleeding.”

Therefore, the combined results of the two studies support the use of low-dose aspirin to prevent both recurrent VTE and major vascular events in patients who have had a first episode of unprovoked VTE, the researchers said.

Lead author Dr. Brighton disclosed serving as a consultant for Pfizer, GlaxoSmithKline, and other companies. The study was supported by grants from the National Health and Medical Research Council (Australia), the Health Research Council (New Zealand), the National Heart Foundation of Australia, Bayer HealthCare (Germany), and the Australasian Society of Haematology and Thrombosis

* This story was updated on 11/7/12.

A 100-mg daily dose of aspirin reduced by one-third the rate of recurrent major vascular events for patients who had one acute unprovoked venous thromboembolism and were switched from anticoagulant therapy to either aspirin or placebo after 3 months of anticoagulant therapy.*

Patients with one episode of unprovoked VTE often discontinue anticoagulant therapy due to inconvenience and the risk of bleeding, said Dr. Timothy A. Brighton of the University of Sydney, Australia, and his colleagues. For those patients, 100 mg of aspirin per day appears to be a safe alternative.

Dr. Brighton and his colleagues reported the findings based on combined data from the ASPIRE (Aspirin to Prevent Recurrent Venous Thromboembolism) study and the WARFASA (Warfarin and Aspirin) study. The findings of ASPIRE were simultaneously published in the New England Journal of Medicine and presented at the annual meeting of the American Heart Association in Los Angeles. The findings of WARFASA were previously published in the same journal.

ASPIRE examined the effect of a 100-mg daily dose of aspirin in patients who had a history of a first-ever unprovoked VTE and had completed initial anticoagulation therapy. The study population included 822 adults who were randomized to a placebo or aspirin at 56 sites in five countries from May 2003 and August 2011. Roughly half of the patients were men; 56% had a proximal deep-vein thrombosis as an index event; 29% had a pulmonary embolism as an index event, and 14% had both conditions as an index event (N. Engl. J. Med. 2012 Nov. 4 [doi: 10.1056/NEJMoa1210384]).

Overall, VTE recurred in 57 patients (14%) in the aspirin group, compared with 73 patients (18%) in the placebo group (rates of 5% and 7% per year, respectively, a nonsignificant difference).

However, the rates of two secondary composite outcomes were significantly reduced in patients who took aspirin compared with those on placebo, the researchers noted. The rate of a composite outcome including VTE, myocardial infarction, stroke, or cardiovascular death was reduced by 34% in aspirin patients (5% per year for aspirin vs. 8% per year for placebo).

The rate of a composite outcome including VTE, myocardial infarction, stroke, major bleeding, or death from any cause was reduce by 33% in aspirin patients (6% per year for aspirin vs. 9% per year for placebo).

No significant differences in serious adverse events or in the rates of major or clinically relevant nonmajor bleeding were observed between the aspirin and placebo groups, the researchers noted.

The findings were limited by the low number of patients in the study, however. The ASPIRE data alone were not adequately powered to show a significant reduction in the recurrence of VTE.

To address the issue, researchers combined the ASPIRE data with data from a similar population of 402 patients in the WARFASA (Warfarin and Aspirin) study (N. Engl. J. Med. 2012; 366:1959-67). In this multicenter, double-blind study, patients with first-ever unprovoked venous thromboembolism completed 6-18 months of oral anticoagulant treatment and were randomly assigned to aspirin, 100 mg daily, or placebo for 2 years.

VTE recurred in 28 of the 205 patients who received aspirin and in 43 of the 197 patients who received placebo (6.6% vs. 11.2% per year; hazard ratio, 0.58; 95% confidence interval [CI], 0.36 – 0.93). One patient in each treatment group had a major bleeding episode. Adverse events were similar in the two groups.

Using the combined data from both studies, the researchers found “a highly significant reduction of 32% in the rate of recurrence of venous thromboembolism and a reduction of 34% in the rate of major vascular events with no excess of bleeding.”

Therefore, the combined results of the two studies support the use of low-dose aspirin to prevent both recurrent VTE and major vascular events in patients who have had a first episode of unprovoked VTE, the researchers said.

Lead author Dr. Brighton disclosed serving as a consultant for Pfizer, GlaxoSmithKline, and other companies. The study was supported by grants from the National Health and Medical Research Council (Australia), the Health Research Council (New Zealand), the National Heart Foundation of Australia, Bayer HealthCare (Germany), and the Australasian Society of Haematology and Thrombosis

* This story was updated on 11/7/12.