Aspirin Effects Vary by Sex

A recent study by researchers from Harvard-affiliated Brigham and Women’s Hospital (BWH) has revealed significant gender differences in the effect of aspirin on men and women.

Aspirin is recommended to people who have had or are undergoing a heart attack, according to Julie E. Buring, principal investigator of the study.

The study, which will be published in the print edition of the New England Journal of Medicine later this month, found that aspirin can reduce the risk of stroke in women, but has little or no effect on the risk of heart attack. The opposite is found in studies conducted with male participants, the study said.

Researchers said that the study highlights the role of genetics in medicine.

“Perhaps we have to think about drugs along gender lines,” said Paul M. Ridker, Harvard Medical School (HMS) Braunwald professor of medicine and a researcher of the study. Testing men and proscribing the results to women ignores “real differences between men and women,” he said.

Researchers monitored nearly 40,000 women for 10 years, comparing those given low doses of aspirin with those taking a placebo, according to the study. The study found that the risk of heart attack in women is largely unaffected by the drug, except in women over the age of 65, who experience both a reduction in the risk of strokes and of heart attacks.

The risk of stroke, however, was 17 percent lower in women taking aspirin as opposed to those taking a placebo, the study said. Similarly, the risk due to blood clotting, the primary cause of strokes, was 24 percent lower in female aspirin users, according to the study.

In 2003, women accounted for around 61 percent of stroke deaths in the United States, according to the American Heart Association. But because of the side-effects associated with aspirin use, there will never be “an across-the-board recommendation,” Buring said.

Women and men who take aspirin face an increased risk of internal bleeding, according to Buring. She also stressed the importance of weighing the adverse effects of aspirin against the potential benefits on an individual basis. “Aspirin is a drug, and that is something people seem to forget,” she said.