Cardiovascular disease (CVD) is the leading cause of death among women, yet very little research has been done focusing specifically on women and CVD. Recent recognition that studies on men are not always applicable to women has led to an increase in clinical research that accounts for gender differences, and focuses on women.

Primary prevention includes educating people about reducing or altering their risk factors for CVD, while secondary prevention identifies and treats people who have CVD without symptoms or are at high risk for CVD. Primary prevention studies on men have shown that aspirin is effective at preventing heart attacks in people who have not previously had one. These results were assumed to apply to women as well, yet no study had been done on a large population of just women.

Researchers interested in pursuing this assumption conducted the largest study to date on the use of aspirin to prevent CVD in women. Their results, published in the March 31, 2005 issue of the New England Journal of Medicine , found that aspirin actually had no effect on women’s risk of heart attack, but did reduce their risk of stroke.

About the Study

The Women’s Health Study was designed to determine the lowest dose of aspirin that would be effective at preventing a first major cardiovascular event ( heart attack , stroke , or death from cardiovascular causes) in women.

The study began in 1993 and followed nearly 40,000 female health professionals for ten years. The participants were age 45 and older, and had no history of heart disease. Half of the group took 100 milligrams of aspirin on alternate days, and the other half took a placebo pill. Researchers monitored the participants from each group for a first major cardiovascular event and compared the results.

The Findings

The study concluded that women taking aspirin were no less likely to experience a heart attack or death from cardiovascular causes than those taking the placebo. However, those in the aspirin group experienced a 17% reduction in the incidence of all strokes and a 24% reduction in the incidence of ischemic strokes (caused by blood clots). Interestingly, these findings are the inverse of what has been determined for men.

Women age 65 and over who took aspirin, however, did experience a 26% reduction in the incidence of both stroke and heart attack.

One of the side effects of aspirin use is stomach bleeding from ulcers; 127 women required a blood transfusion due to this condition.

How Does This Affect You?

Although the results of this study are important, further research will help discover the reason for the sex-based differences in aspirin therapy, and determine the best course of action for women under 65.

The decision to use aspirin is ultimately made by a woman and her doctor, and should be based on a careful review of the risks and benefits. Women who are 65 or older and have no problems with stomach bleeding may safely reduce their risk of stroke or heart attack by taking a low dose of aspirin. This is especially true for women at risk of having a cardiovascular event in the next ten years, since the benefits of aspirin are likely to outweigh its risks.

CVD is highly preventable. Regardless of whether aspirin therapy is recommended or not, women should adopt lifestyle habits that are proven to reduce CVD risk: eat a healthful diet; exercise regularly; maintain a healthy weight; avoid tobacco; and control high blood pressure , high cholesterol , and diabetes .