Study: Aspirin’s Benefit to Women Mixed ; Stroke Risk Reduced, but Heart Attack Help Only in Those Over 65

ORLANDO, Fla.- In a stunning example of gender differences in medicine, a major new study found that aspirin helps healthy women avoid strokes but makes no difference in their risk of heart attacks unless they’re 65 or older — the polar opposite of how the drug affects men.

Aspirin is recommended now for both men and women at high risk of heart disease. Many doctors have assumed it also prevented heart problems in healthy women because of research showing it helped healthy men.

The new study “raises issues about the dangers of generalization,” said Dr. Paul Ridker of Harvard Medical School and Brigham and Women’s Hospital in Boston, one of the researchers. “This is an issue we thought we already had an answer to.”

The Women’s Health Study was the first rigorous test of aspirin and vitamin E in women. It found that taking vitamin E did no good, adding to a large body of evidence that such supplements don’t help and might even be harmful.

“Bottom line: There wasn’t a benefit but there wasn’t harm” from vitamin E in the new study, said Harvard epidemiologist Julie Buring. “The better thing to do is to have a heart-healthy diet.”

She presented results Monday at the American College of Cardiology meeting. They also were published online by the New England Journal of Medicine and will be in the March 31 print edition.

“This is a very important study with major public health implications,” said Dr. Elizabeth Nabel, director of the National Heart, Lung and Blood Institute, which funded it with the National Cancer Institute.

Many of the authors have been consultants to aspirin makers, but the companies did not run the study. Bayer Healthcare supplied aspirin for it and the Natural Source Vitamin E Association supplied that nutrient.

Nearly 40,000 female health professionals 45 and older were randomly assigned to take either fake pills or 100 milligrams of aspirin — slightly more than the 81-milligram “baby aspirin” pills commonly sold — every other day.

After 10 years, aspirin users had a 17 percent lower risk of stroke and a 24 percent lower risk of strokes caused by blood clots – - the majority of strokes — probably due to aspirin’s well-known anti-clotting properties, researchers believe.

Helpful, but not without risk

Women 65 and older got the most benefit: They were 30 percent less likely to have a stroke caused by a blood clot and 34 percent less likely to suffer a heart attack.

But the benefits came with a cost. Stomach or intestinal bleeding requiring a blood transfusion occurred in 127 women on aspirin and in 91 women taking dummy pills.

“Is it manageable? Yes. Is it worth it? That’s an individual decision,” Nabel said, adding that anyone considering taking aspirin should talk with his or her doctor about the relative risks.

The results generally are good news, because women proportionately suffer more strokes and men more heart attacks; therefore aspirin cuts the risk of the top concern for each sex, specialists said.

In 2002, there were 345,000 heart attacks in American women and 373,000 strokes. Men suffered 520,000 heart attacks and 327,000 strokes.

But they also point out the gender gap in medical studies, which involve too few women, elderly and minorities, said Dr. Sidney C. Smith, a spokesman for the American Heart Association and cardiology chief at the University of North Carolina who has been a speaker in the past for Bayer.

“We do our best on intuition, but when it comes to medical therapy, you want more than intuition on your side,” Smith said.

The new study fills gaps in knowledge because virtually all research in the past on this issue was done in men, Buring said.

“We finally have the evidence base needed for women to make rational decisions about the use of aspirin in preventing cardiovascular disease,” she said.

Reasons for the gender differences are unclear. Strokes usually occur from blood clots that form in neck arteries; heart attacks, from coronary artery clots. Aspirin may affect one or the other more in men than in women.