An analysis of previous studies indicates that use of aspirin significantly reduces the risk of cardiovascular events in women and in men, due to reducing the risk of stroke in women and reducing the risk of heart attack in men, according to a study in the January 18 issue of JAMA.

Although the benefits of aspirin therapy for reducing the risk of heart attack (myocardial infarction – MI), stroke, and vascular death among men and women with preexisting cardiovascular disease are well established, the role of aspirin in primary prevention is less clear, according to background information in the article. And it has not been clear if there is a differential beneficial effect between men and women.

Jeffrey S. Berger, M.D., M.S., of Duke University, Durham, N.C., and colleagues performed a sex-specific meta-analysis of aspirin therapy for the primary prevention of cardiovascular events to better understand the association of sex with the response to aspirin.

The researchers performed a search of databases to identify randomized controlled trials of aspirin therapy in participants without cardiovascular disease that reported data on heart attack, stroke, and cardiovascular death. Six trials with a total of 95,456 individuals were identified; 3 trials included only men, 1 included only women, and 2 included both sexes. The authors examined a combined endpoint of any major cardiovascular event (cardiovascular death, nonfatal heart attack, or nonfatal stroke), and each of these individual components separately.

The researchers found that among the 51,342 women, there were 625 strokes, 469 heart attacks, and 364 cardiovascular deaths. Aspirin therapy was associated with a significant 12 percent reduction in cardiovascular events and a 17 percent reduction in stroke, which was a reflection of a 24 percent reduced rate of ischemic stroke. There was no significant effect on heart attacks or cardiovascular death.

Among the 44,114 men, there were 597 strokes, 1,023 heart attacks, and 776 cardiovascular deaths. Aspirin therapy was associated with a significant 14 percent reduction in cardiovascular events and a 32 percent reduction in heart attacks. There was no significant effect on stroke or cardiovascular death. Aspirin treatment resulted in an approximately 70 percent increase in the risk of major bleeding events among women and men.

The authors add that aspirin therapy for an average of 6.4 years results in an average absolute benefit of approximately 3 cardiovascular events prevented per 1,000 women and 4 cardiovascular events prevented per 1,000 men.

“… the favorable effect of aspirin on the combined risk of cardiovascular events for women and men is apparent from these randomized studies. Aspirin use is also associated with a significant risk of major bleeding irrespective of sex. Both the beneficial and harmful effects of aspirin should be considered by the physician and patient before initiating aspirin for the primary prevention of cardiovascular disease in both sexes,” the authors conclude.

(JAMA. 2006;295:306-313. Available pre-embargo to the media at http://www.jamamedia.org)