Aspirin use, dose, and clinical outcomes in postmenopausal women with stable cardiovascular disease: the Women's Health Initiative Observational Study.

BACKGROUND: Despite compelling evidence that aspirin reduces fatal and nonfatal vascular events among the overall population in various settings, women have frequently been underrepresented and their data underreported. We sought to evaluate the relationship between aspirin use, dose (81 or 325 mg), and clinical outcomes among postmenopausal women with stable cardiovascular disease (CVD). METHODS AND
RESULTS: Women with CVD (n=8928) enrolled in the Women's Health Initiative Observational Study were used for this analysis. The primary outcome was the incidence of all-cause mortality and cardiovascular events (myocardial infarction, stroke, and cardiovascular death). Among 8928 women with stable CVD, 4101 (46%) reported taking aspirin, of whom 30% were on 81 mg and 70% were on 325 mg. At 6.5 years of follow-up, no significant association was noted for aspirin use and all-cause mortality or cardiovascular events. However, after multivariate adjustment, aspirin use was associated with a significantly lower all-cause (adjusted hazard ratio, 0.86 [0.75 to 0.99]; P=0.04) and cardiovascular-related mortality (adjusted hazard ratio, 0.75 [0.60 to 0.95]; P=0.01) compared with no aspirin. Aspirin use was associated with a lower risk of cardiovascular events (adjusted hazard ratio, 0.90 [0.78 to 1.04]; P=0.14), which did not meet statistical significance. Compared with 325 mg, use of 81 mg was not significantly different for all-cause mortality, cardiovascular events, or any individual end point.
CONCLUSIONS: After multivariate adjustment, aspirin use was associated with significantly lower risk of all-cause mortality, specifically, cardiovascular mortality, among postmenopausal women with stable CVD. No significant difference was noted between 81 mg and 325 mg of aspirin. Overall, aspirin use was low in this cohort of women with stable CVD.