Background and purpose: Although aspirin is effective in prevention of stroke, fewer studies have examined the impact of aspirin on stroke morbidity.
Methods: The Women's Health Study is a completed randomized, placebo-controlled trial designed to test the effect of low-dose aspirin and vitamin E in the primary prevention of cardiovascular disease and cancer, which enrolled 39 876 women. We used multinomial logistic regression to evaluate the relationship between randomized aspirin assignment and functional outcomes from stroke. Possible functional outcomes were neither stroke nor transient ischemic attack (TIA), modified Rankin scale (mRS) score 0 to 1, 2 to 3, and 4 to 6.
Results: After a mean of 9.9 years of follow-up, 460 confirmed strokes (366 ischemic, 90 hemorrhagic, and 4 unknown type) and 405 confirmed TIAs occurred. With regard to total and ischemic stroke, women who were randomized to aspirin had a nonsignificant decrease in risk of any outcome compared to women not randomized to aspirin. This decrease in risk only reached statistical significance for those experiencing TIA compared to participants without stroke or TIA (odds ratio=0.77; 95% confidence interval, 0.63-0.94). For hemorrhagic stroke, a nonsignificant increase in the risk of achieving an mRS score 2 to 3 or 4 to 6 compared with no stroke or TIA was observed for the women randomized to aspirin compared to those randomized to placebo.
Conclusions: Results from this large randomized clinical trial provide evidence that 100 mg of aspirin every other day may reduce the risk of ischemic cerebral vascular events but does not have differential effects on functional outcomes from stroke.