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Aspirin's Cardiac Benefits Differ by Gender

January 23, 2006

Aspirin can help prevent cardiovascular events, but its effects differ between men and women, according to a new report.

The meta-analysis of data from over 51,000 women and 44,0000 men was published in the January 18 issue of the Journal of the American Medical Association and reported by MedPage Today on January 17, 2006.

In men, the analysis showed that aspirin helps to protect against heart attack, whereas in women it helps to protect against ischemic stroke. Also, aspirin protects men-but not women-against myocardial infarction (MI), and it does not protect either gender against cardiovascular mortality.

The meta-analysis was conducted by David L Brown, MD, of the State University of New York and colleagues from other medical centers.

"This is good news because many of the past studies of the effect of aspirin in preventing cardiovascular events looked only at men, so physicians were reluctant to prescribe aspirin for women because there was little data," said co-author Jeffrey Berger, MD of Duke University in Durham, NC, to MedPage Today. "But now, the combined data of recent trials involving women demonstrates that women can benefit just as much from aspirin therapy as men."

For both men and women, aspirin also significantly increased the incidence of major bleeding episodes.

Although the meta-analysis found gender differences in protective cardiovascular effects of aspirin, the authors noted that that, because men have a relatively small stroke incidence and women have fewer heart attacks, determining whether the genders differ in their physical responses to aspirin is difficult.

Clinical Trial

Berger et al conducted the meta-analysis to determine whether gender-based differences exist regarding the risks and benefits of aspirin for primary prevention of cardiovascular disease. The study included randomized, controlled trials of aspirin therapy in participants without cardiovascular disease, and every trial included data on MI, stroke and mortality. Primary endpoints included a composite of cardiovascular events (non-fatal MI, nonfatal stroke and cardiovascular mortality), each component separately, and major bleeding.

Women: Among the 51,342 women, 1,285 major cardiovascular events occurred: 625 strokes, 469 MIs and 364 cardiovascular deaths. Aspirin use in these women was associated with a 12% decrease in cardiovascular events and a 17% decrease in stroke that reflected a decrease in rates of ischemic stroke. Aspirin had no significant effect on MI or cardiovascular mortality among women.

Men: Among the 44,114 men, 2,047 major cardiovascular events occurred: 597 strokes, 1,023 MIs and 776 cardiovascular deaths. Similar to its effect in women, aspirin therapy in these men was associated with a 14% decrease in cardiovascular events; however, MI in the men also decreased (32%). Aspirin did not affect stroke risk or cardiovascular mortality in men.

Aspirin increased bleeding-risk by about 70% in both genders, with the gastrointestinal tract the major site of bleeding.

Benefits of Aspirin

Study results showed that taking aspirin for an average of 6.4 years results in an absolute benefit of three fewer cardiovascular events per 1,000 women, and four fewer events per 1,000 men, the investigators wrote.

The authors noted that the composite study population had a low risk of fatal or non-fatal vascular events. Because the cardio-protective benefit of aspirin is related to cardiovascular risk in a given study the population, the absolute risk-reduction for these events was small.

"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 said. They also noted that a "meta-analysis remains retrospective research that is subject to the methodological deficiencies of the included studies."

Aspirin Prevents Stroke in Women and Heart Attack in Men, MedPage Today, January 17, 2006.
Aspirin for the Primary Prevention of Cardiovascular Events in Women and Men: A Sex-Specific Meta-analysis of Randomized Controlled Trials. Berger JS et al, Journal of the American Medical Association, volume 295, pages 306-313.

Posted: January 2006