Aspirin and risk of hemorrhagic stroke - A meta-analysis of randomized controlled trials

Context.-Aspirin has been widely used to prevent myocardial infarction and ischemic stroke but some studies have suggested it increases risk of hemorr hagic stroke. Objective-To estimate the risk of hemorrhagic stroke associated with aspiri n treatment. Data Sources.-Studies were retrieved using MEDLINE (search terms, aspirin, cerebrovascular disorders, and stroke), bibliographies of the articles retr ieved, and the authors' reference files. Study Selection.-All trials published in English-language journals before J uly 1997 in which participants were randomized to aspirin or a control trea tment for at least 1 month and in which the incidence of stroke subtype was reported. Data Extraction.-Information on country of origin, sample size, duration, s tudy design, aspirin dosage, participant characteristics, and outcomes was abstracted independently by 2 authors who used a standardized protocol, Data Synthesis.-Data from 16 trials with 55 462 participants and 108 hemorr hagic stroke cases were analyzed. The mean dosage of aspirin was 273 mg/d a nd mean duration of treatment was 37 months. Aspirin use was associated wit h an absolute risk reduction in myocardial infarction of 137 events per 10 000 persons (95% confidence interval [CI], 107-167; P<.001) and in ischemic stroke, a reduction of 39 events per 10 000 persons (95% CI, 17-61; P<.001 ), However, aspirin treatment was also associated with an absolute risk inc rease in hemorrhagic stroke of 12 events per In 000 persons (95% CI, 5-20; P<.001). This risk did not differ by participant or study design characteri stics. Conclusions.-These results indicate that aspirin therapy increases the risk of hemorrhagic stroke; However, the overall benefit of aspirin use on myoc ardial infarction and ischemic stroke may outweigh its adverse effects on r isk of hemorrhagic stroke in mast populations.