Low-dose Aspirin Shown to Reduce Risk of First Stroke in Women
Results of 10-year clinical trial suggest most consistent benefits among women 65 years and older
Boston, MA – In a long-awaited clinical trial conducted among nearly 40,000 initially healthy middle-aged American women, regular use of low-dose aspirin over a ten-year period was found to reduce the risk of stroke 17 percent. However, among the same population, researchers from the Brigham and Women’s Hospital (BWH) also found that low-dose aspirin did not benefit most women in terms of preventing first heart attacks or cardiac deaths.
“Although not widely recognized, women tend to suffer more strokes than heart attacks as compared to men, and thus these prevention data for low-dose aspirin have important public health implications,” said BWH’s Julie E Buring, ScD and principal investigator of the Women’s Health Study (WHS). The results of the cardiovascular component of the WHS are being presented at the American College of Cardiology (ACC) 54th Annual Scientific Session in Orlando, Florida and will also be published simultaneously in the New England Journal of Medicine online March 7, 2005 and then in print in the March 31, 2005 issue.
The WHS is a large, randomized, double-blind, placebo controlled trial funded by both the National Heart, Lung and Blood Institute and the National Cancer Institute to evaluate the benefits and risks of low dose aspirin (100 mg every other day) as well as vitamin E supplementation (600 IU every other day) in the primary prevention of cardiovascular disease. The trial included 39,876 healthy women 45 years of age and older who were monitored for 10 years for first major cardiovascular events including heart attack, stroke and death from cardiovascular causes.
With regard to aspirin, while previous trials primarily done in men have shown aspirin to be effective in lowering the risk of a first heart attack, data addressing this question in women have been limited. During follow-up, 477 major cardiovascular events were confirmed in the aspirin group as compared to 522 in the placebo group, a 9 percent overall reduction that was not statistically significant. However, in a pattern seemingly different to that previously observed among men, the benefit of aspirin within the WHS was due almost entirely to a statistically significant reduction in stroke events without a reduction in heart attack rates. The most consistent benefits were observed among women 65 years of age and older; a group that comprised ten percent of the study population yet suffered one-third of all cardiovascular events. Among such women, low-dose aspirin use resulted in a 26 percent reduction in risk of major cardiovascular events. By contrast, low-dose aspirin showed little benefit among younger women, an important issue as aspirin use is also known to increase the risk of bleeding.
“The WHS overwhelmingly demonstrates the importance of studying medical therapies among women as well as men,” said Buring. “We finally have the evidence base needed for women to make rational decisions about the use of aspirin in preventing cardiovascular disease.”
“From a clinical standpoint, the new data suggest that many women, particularly those over the age of 65, are likely to attain a net benefit from preventive aspirin therapy,” said Paul Ridker, MD a BWH cardiologist also involved in the WHS clinical trial. “However, as with men, women considering the use of aspirin to prevent cardiovascular disease must balance both benefits and risks, and thus should consult with their personal physician before beginning therapy.”
Buring also presented data at the ACC meeting evaluating vitamin E as compared to placebo in the same group of nearly 40,000 women. Overall, women allocated to vitamin E had almost exactly the same risk of future cardiovascular events as did those allocated to placebo. “We found no evidence that dietary supplementation with vitamin E lowered risk of a first cardiovascular event,” said Buring, who is also a professor of Ambulatory Care and Prevention at Harvard Medical School. “With regard to vitamin E supplementation, the bottom line is that eating healthy foods and living a healthy lifestyle remain a woman’s best choice for long term heart disease prevention.”
The WHS was funded by both the National Heart, Lung and Blood Institute and the National Cancer Institute, with aspirin and aspirin placebo provided by Bayer HealthCare, and vitamin E and vitamin E placebo provided by the Natural Source Vitamin E Association.
Please contact BWH Media Relations for more information at (617) 534-1600 or BWHMediaRelations@partners.org.
BWH is a 747-bed nonprofit teaching affiliate of Harvard Medical School and a founding member of Partners HealthCare System, an integrated health care delivery network. BWH is committed to excellence in patient care with expertise in virtually every specialty of medicine and surgery. The BWH medical preeminence dates back to 1832 and today that rich history in clinical care is coupled with its national leadership in quality improvement and patient safety initiatives, dedication to educating and training health care professionals, and strength in biomedical research. With $370M in funding and more than 500 research scientists, BWH is an acclaimed leader in clinical, basic and epidemiological investigation - including the landmark Nurses Health Study, Physicians Health Studies, and the Women's Health Initiative. For more information visit www.brighamandwomens.org
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