Aspirin prophylaxis cuts strokes in healthy women: benefits clearest for those 65 and older.(Gynecology)

ORLANDO, FLA. -- Aspirin's role in preventing initial cardiovascular events in women was dramatically focused by the results of the first study to test aspirin prophylaxis in a large number of apparently healthy women, the Women's Health Study.

The clearest result was that among women at least 65 years old, a regimen of 100 mg of aspirin every other day cut the incidence of ischemic stroke, MI, and all major cardiovascular disease (CVD) events, while causing a small number of adverse events. Among women younger than 65, the benefit was limited to cutting the risk of ischemic strokes, and the reduction was so modest that aspirin prophylaxis will have to be targeted to a select group of women for whom the likely benefits of regular aspirin will outweigh the risks.

"For women 65 and older, the risk and benefit balance may tip toward benefit, but for women younger than 65, patients and physicians will need to look very carefully," Julie E. Buring, Sc.D., said during the annual meeting of the American College of Cardiology.

The results also surprised researchers by the way they high lighted intrinsic differences in the way that CVD plays out in women, compared with men. In this study of women, strokes were more common than MIs, and aspirin's benefit was largely in stroke prevention. In contrast, results from prior studies in healthy men, including the very similarly designed Physicians' Health Study, showed that MIs were the primary threat and that the benefit from aspirin prophylaxis was greatest for MI prevention.

"The results show the danger of generalization," said Paul M. Ridker, M.D., director of the Center for Cardiovascular Disease Prevention at Brigham and Women's Hospital in Boston and co-principal investigator for the study along with Dr. Buring.

"The finding that women behave differently than men with respect to aspirin was not what we expected, but we shouldn't be that surprised. Many of us look for genetic effects, and gender is the ultimate genetic effect," he continued.

For example, in 2002, American women had 373,000 new strokes and 345,000 new MIs, said Dr. Buring, a professor of epidemiology at Harvard School of Public Health, Boston. In contrast, men had 520,000 new MIs and 323,000 new strokes.