Aspirin therapy affects men, women differently

Orlando -- Gender is shaping up as the "ultimate pharmacologic effect," according to Paul Ridker, MD, senior investigator of the Women's Health Study, which has effectively derailed low-dose aspirin for primary prevention of heart attacks in women.

"I was very surprised by these results because this is exactly the opposite of what we see in men," said Dr. Ridker, who reported the results from the 40,000-woman study at the March American College of Cardiology Scientific Sessions.

The findings, which also were released online by the New England Journal of Medicine, found that 10 years of aspirin therapy (100 mg every other day) did not reduce the risk of first myocardial infarction nor did it reduce the risk of death from heart disease compared with placebo.

But low-dose aspirin did reduce women's risk of stroke by 17% and the risk of ischemic stroke by 24%. Although the study enrolled 39,876 healthy women ages 45 to 80, the stroke benefit is "greatest among women ages 65 and older, which is to be expected, since stroke risk increases with age," explained Julie Buring, ScD, Dr. Ridker's co-investigator.

Dr. Ridker said the clinical implications of the study are fairly straightforward and the decision to take aspirin should be between a woman and her doctor based on careful consideration of risks and benefits. Dr. Buring added that "for women over age 65, I would say that the benefit of stroke prevention outweighs the risk." These include increased rate of gastrointestinal bleeding and a nonsignificant increase in the risk of hemorrhagic stroke.

Meanwhile, the results pertain only to prevention of heart attacks or stroke in people with no history of heart disease, Dr. Buring said. For anyone who has had a heart attack, aspirin is still recommended to reduce risk of a second heart attack. Also, for someone having a heart attack -- man or woman -- the recommendation is still to take an aspirin to limit the damage.

Robert Harrington, MD, a professor of medicine and director of cardiovascular trials at Duke University School of Medicine in Durham, N.C., said he thought the findings were unambiguous. "We need to talk to our women patients aged 65 or older about stroke prevention with aspirin. But for younger women, it looks like aspirin is not a good option." Dr. Harrington chaired an ACC press conference where study results were discussed.

The American Heart Assn. responded with an official statement urging doctors to check the AHA's evidence-based guidelines on cardiovascular disease prevention in women. Lori Mosca, MD, who serves as chair of the AHA writing group on guidelines for women, said the AHA does not recommend routine use of aspirin for primary prevention in women. Dr. Mosca also said the AHA would study the stroke findings before making any changes in recommendations.