Meta-Analysis of Multiple Primary Prevention Trials of Cardiovascular Events Using Aspirin Alfred A. Bartolucci, PhD,a,* Michal Tendera, MDb, and George Howard, DrPHa Several meta-analyses have focused on determination of the effectiveness of aspirin (ace-tylsalicylic acid) in primary prevention of cardiovascular (CV) events. Despite these data,the role of aspirin in primary prevention continues to be investigated. Nine randomizedtrials have evaluated the benefits of aspirin for the primary prevention of CV events: theBritish Doctors' Trial (BMD), the Physicians' Health Study (PHS), the Thrombosis Pre-vention Trial (TPT), the Hypertension Optimal Treatment (HOT) study, the PrimaryPrevention Project (PPP), the Women's Health Study (WHS), the Aspirin for Asymptom-atic Atherosclerosis Trial (AAAT), the Prevention of Progression of Arterial Disease andDiabetes (POPADAD) trial, and the Japanese Primary Prevention of Atherosclerosis WithAspirin for Diabetes (JPAD) trial. The combined sample consists of about 90,000 subjectsdivided approximately evenly between those taking aspirin and subjects not taking aspirinor taking placebo. A meta-analysis of these 9 trials assessed 6 CV end points: total coronaryheart disease, nonfatal myocardial infarction (MI), total CV events, stroke, CV mortality,and all-cause mortality. No covariate adjustment was performed, and appropriate tests fortreatment effect, heterogeneity, and study size bias were applied. The meta-analysis suggestedsuperiority of aspirin for total CV events and nonfatal MI, (p <0.05 for each), with nonsignif-icant results for decreased risk for stroke, CV mortality, and all-cause mortality. There was noevidence of a statistical bias (p >0.05). In conclusion, aspirin decreased the risk for CV eventsand nonfatal MI in this large sample. Thus, primary prevention with aspirin decreased the riskfor total CV events and nonfatal MI, but there were no significant differences in the incidencesof stroke, CV mortality, all-cause mortality and total coronary heart disease.