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March 1, 2006. The battle of the sexes may even extend to aspirin: A new meta-analysis, or "study of studies," finds the cardio-protective medication benefits men differently than it does women, according to a report in the Journal of the American Medical Association (JAMA).

The review of six studies, involving more than 95,000 persons, shows that aspirin therapy cut the incidence of stroke in women but not men. On the other hand, when it came to heart attack the reverse was true: Daily use of aspirin reduced the incidence of those events in men but not women. "Nobody has any ideas about the cause of the difference," says study senior author Dr. David L. Brown, chief of cardiology at the State University of New York at Stony Brook. "It needs to be an important research priority for the future," says Dr. Brown.

Looking at Aspirin Metabolization Next

He believes future research on the issue should center on factors such as how women and men "metabolize [break down and process in the body] aspirin, and how it acts on blood platelets [blood cells involved in blood clotting] and blood vessels." Three of the trials included only men, one included only women, and two included both sexes. All the participants were free of cardiovascular conditions at the start of the studies.

Overall, there was a 12 percent reduction in all cardiovascular events in women who took aspirin as compared to those who did not. The reduction for men was 14 percent. But those reductions occurred in strikingly different ways, based on gender. Aspirin treatment lowered the incidence of heart attacks in men by 32 percent, but had no effect on their incidence of stroke. For women, aspirin therapy decreased the incidence of stroke by 17 percent, with no significant effect on their risk of heart attack. "This adds to the continued research that men and women are different," notes Dr. Nieca Goldberg, chief of women's cardiac care at Lenox Hill Hospital in New York City, and author of the book Women Are Not Small Men. Aspirin has benefits for both sexes, "particularly when it comes to healthy men and women, those without heart disease or risk factors," she adds.

But risk factors such as high blood pressure and diabetes have to be taken into account when aspirin therapy is under consideration, says Dr. Brown. "The risk-benefit ratio has to be considered for any patient," he says. "The benefit is based on the risk factor profile, and the risk is based on the presence of such things as previous bleeding events and peptic ulcers."

Ask a Physician Before Starting Aspirin

No one should start taking aspirin before consulting a physician because it can cause bleeding. Aspirin therapy resulted in a 70 percent increase in the risk of major bleeding episodes across the six studies. Those studies offered no firm guideline on the amount of aspirin to be taken, Dr. Brown notes. The dosages ranged from a high of 500 milligrams a day, "which today no one would consider," to 100 milligrams every other day, he says. "I think a reasonable dose is 81 milligrams a day, the amount in one baby aspirin," explains Dr. Brown.

Always consult your physician for more information.