New results from the Women's Health Initiative (WHI) Observational Study provide additional evidence that aspirin may reduce the risk of death in postmenopausal women who have heart disease or who have had a stroke. Jacques Rossouw, M.D., chief of the Women's Health Initiative Branch at the National Heart, Lung, and Blood Institute (NHLBI), is available to comment on these findings. NHLBI, part of the National Institutes of Health, funded the research.
The study also provides new insight into aspirin dosing for women, suggesting that a lower dose of aspirin (81 milligrams, or mg) is as effective as a higher dose (325 mg). This is good news for women who might be concerned with internal bleeding, a well-known risk of aspirin that may be more likely with higher doses of aspirin, according to other studies. However, randomized clinical trials are needed to determine the optimal doses of aspirin in women with cardiovascular disease.
"Aspirin Use, Dose, and Clinical Outcomes in Postmenopausal Women with Stable Cardiovascular Disease The Women's Health Initiative Observational Study," appears in the March issue of the journal Circulation: Cardiovascular Quality and Outcomes and was published online March 5, 2009.
Scientific evidence indicates that, in general, aspirin lowers the risk of death and incidence of heart attack and stroke in patients with a history of cardiovascular disease; however, the benefits of aspirin in women with stable cardiovascular disease in particular are unknown. In this study, researchers analyzed data from 8,928 postmenopausal women who had previously had a heart attack, stroke or transient ischemic attack (TIA, or mini-stroke), angina, or angioplasty or coronary bypass surgery to improve blood flow. Participants were followed for an average of 6.5 years.
Compared to those who did not report taking aspirin, regular aspirin users had a 25 percent lower risk of death from cardiovascular disease and a 14 percent lower risk of death from any cause. Overall, aspirin use did not significantly decrease the risk of heart attack, stroke, or other cardiovascular events, except among women in their seventies. There were no significant differences in death rates or other outcomes between women taking 81 mg of aspirin compared to those taking 325 mg.
The size of the WHI Observational Study and the diversity of participants provide valuable insight into the use of medications in the primary care setting. For example, the study found that only 46 percent of women with stable cardiovascular disease in the study reported taking aspirin regularly, despite current guidelines recommendations. In addition, subgroup analyses indicate that black women and women with Medicaid insurance were less likely to use aspirin as recommended, compared to women of other ethnic groups and insurance status.
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NIH/National Heart, Lung and Blood Institute