Figure 2. Meta-analysis of the effect of aspirin on coronary heart disease mortality (top), fatal and nonfatal stroke events (middle), and all-cause mortality (bottom). Results of the chi-square test for heterogeneity were 2.96 for coronary heart disease mortality, 5.36 for fatal and nonfatal stroke events, and 1.58 for all-cause mortality (P > 0.2 in all cases). BMD = British Male Doctors' Trial; HOT = Hypertension Optimal Treatment Trial; OR = odds ratio; PHS = Physicians' Health Study; PPP = Primary Prevention Project; TPT = Thrombosis Prevention Trial.