This study analyzed combined results from 13 randomized clinical trials with more than 164,000 participants to assess aspirin use with the prevention of cardiovascular events and bleeding in people without cardiovascular disease.

Results suggest aspirin use was associated with lower risk (absolute risk reduction of 0.38%) for cardiovascular events (a composite of cardiovascular death, nonfatal heart attack, and nonfatal stroke) and increased risk of major bleeding (absolute risk increase of 0.47%). The role of aspirin for the primary prevention of cardiovascular events has remained controversial because of an increased risk for bleeding. This study (a meta-analysis that combines the results of multiple studies identified in a systematic review) is limited by the availability and quality of reported data.