In a clinical trial involving nearly 40,000 initially healthy middle-aged American women, regular use of low-dose aspirin over a ten-year period was found to reduce the risk of stroke 17 per cent. However, among the same population, low-dose aspirin did not appear to prevent first heart attacks or cardiac deaths. These are findings from the Women’s Health study, led by Brigham and Women's Hospital (BWH) researchers Julie Buring, and Paul Ridker.

This study “overwhelmingly demonstrates the importance of studying medical therapies among women as well as men,” said BWH’s Julie Buring, principal investigator of the Women’s Health Study. “Although not widely recognized, women tend to suffer more strokes than heart attacks as compared to men, and thus these prevention data for low-dose aspirin have important public health implications,” she said.

The Women’s Health Study is a large, randomized, double-blind, placebo-controlled trial to evaluate the benefits and risks of low-dose aspirin (100 mg every other day) as well as vitamin E supplementation (600 IU every other day) in the primary prevention of cardiovascular disease. The trial included 39,876 healthy women with 45 years of age and older who were monitored for 10 years for first major cardiovascular events including heart attack, stroke and death from cardiovascular causes.

“From a clinical standpoint, the new data suggest that many women, particularly those over the age of 65, are likely to attain a net benefit from preventive aspirin therapy,” Paul Ridker, a BWH cardiologist also involved in the WHS clinical trial said adding, “However, as with men, women considering the use of aspirin to prevent cardiovascular disease must balance both benefits and risks, and thus should consult with their personal physician before beginning therapy.”

The study also evaluated vitamin E as compared to placebo in the same group of nearly 40,000 women. Overall, women who took vitamin E had almost exactly the same risk of future cardiovascular events as did those allocated to placebo.