Aspirin study refocuses prevention message for women

Aspirin therapy does less than anticipated in preventing heart attacks in women — but more than we knew in warding off strokes.

Everyone was surprised by the long-awaited results of the Women's Health Study, released in March 2005. The 10-year study of almost 40,000 healthy women showed that low-dose aspirin did not protect them from first heart attacks but did modestly reduce their risk of stroke. Results were almost the opposite of those from earlier trials that involved mostly men. Those studies, which included the landmark Physicians' Health Study, showed that aspirin therapy lowers the risk of heart attack but slightly increases the risk of having a stroke. Do the reverse findings mean that men and women respond differently to aspirin?

Sex-based differences could theoretically play a role in who benefits from aspirin therapy. Certainly, the Women's Health Study findings underscore the need to investigate medications and other interventions in women as well as men. We also want to make sure that studies involving both sexes are designed to take gender into account. But it's unclear whether sex is the reason for the differences reported in these studies. Age appears to be more relevant: Older aspirin takers in the Women's Health Study did have a lower risk for heart attack.

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