Twice-a-day aspirin could increase stroke risk

For years, the medical and pharmaceutical industries have recommended taking daily aspirin as a way to reduce the risk of stroke.

However, a study published in the September 1999 issue of Stroke: Journal of the American Heart Association found that taking more than 15 aspirin tablets per week -- what researchers consider a "high dose" -- doubles the risk of developing a hemorrhagic stroke, caused by bleeding in the brain.

Ischemic stroke, the most common form of stroke, is caused by blood clots or other blockages in the arteries, thus restricting blood flow to the brain. Hemorrhagic strokes occur when a blood vessel or vessels inside the brain ruptures and bleeds, and is more likely to be fatal than an ischemic stroke.

"This is the first large-scale detailed study of the relationship between aspirin use and the risk of principal types of stroke," says lead author JoAnn E. Manson, M.D., professor of medicine at Harvard Medical School and Brigham and Women's Hospital.

Researchers examined aspirin use and stroke risk in 79,319 healthy women ages 34-59, and monitored participants over a 14-year period from 1980 to 1994 during which 295 ischemic strokes and 100 hemorrhagic strokes were recorded.

Dr. Manson noted that, while some research studies in the past have suggested when taken regularly by heart attack and stroke survivors, small doses of aspirin have been shown to help prevent recurrences, medical debate continues about whether healthy people with no history of cardiovascular disease should routinely use aspirin as a method to prevent a first heart attack or stroke.

Women who took more than 15 aspirin tablets per week were approximately twice as likely to suffer hemorrhagic strokes. The risk of hemorrhagic stroke was tripled in older women with high blood pressure who took more than 15 aspirins per week compared to women who did not take aspirin or took lower doses.

"This study indicates that it may be a good news-bad news situation in terms of the primary prevention of stroke," said Manson. "If low doses of aspirin reduce the risk of ischemic stroke in healthy individuals, this is important, since it is the most prevalent form of stroke. On the other hand, our findings suggest that taking too much aspirin could be dangerous."

SOURCES: Media advisory, American Heart Association, Sept. 2, 1999.