For example, 1 observational study found that the overall hemorrhagic event incidence was 5.58 (95% CI, 5.39 5.77) per 1000 person-years for aspirin users compared nonusers (incidence rate ratio, 1.55; 95% CI, 1.48 1.63).872 A meta-analysis of 9 clinical trials including 50868 subjects found no overall benefit of aspirin for the primary preven- with no heterogeneity among trials.873 Similarly, a second meta-analysis of 9 trials with 100076 subjects found that aspirin reduced the risk of ischemic stroke (RR, 0.86; 95% CI, 0.75 0.98), but this benefit was offset by an increase in hemorrhagic stroke (RR, 1.36; 95% CI, 1.01 1.82), again with no heterogeneity among trials.874 A third meta-analysis had similar results (risk of stroke, 0.20%/y versus 0.21%/y, other stroke, 0.16%/y versus 0.18%/y, P=0.08, aspirin versus Taken together, these results reflect risk but no benefit of aspirin for the prevention of a first stroke in the general population. The US Preventive Services Task Force recommends aspirin at a dose of 75 mg/d to prevent MI (but not stroke) in men 45 to 79 years of age and to pre- vent stroke in women 55 to 79 years of age on the basis of their vascular risk and the chances of serious gastrointestinal The US Preventive Services Task Force further notes that the 10-year level of cardiovascular risk for which the benefit exceeds bleeding risk varies from 3% to 11%, depending on age and sex. 