Aspirin Efficacy in Primary Prevention: A Meta-analysis of Randomized Controlled Trials

Abstract

Introduction: The role of aspirin as a means of primary prevention remains controversial. Aim: We have conducted a meta-analysis of all randomized controlled trials (RCTs) to evaluate the role of aspirin in primary prevention. Methods: Literature search was performed via PubMed, Embase, and the Cochrane Library for all related RCTs. All-cause mortality was the primary endpoint. Secondary endpoints included major adverse cardiovascular events (MACE), myocardial infarction (MI), cardiovascular mortality, cerebrovascular events, and bleeding events. We used a random effects model to report the risk ratios (RRs) with 95% confidence intervals (CIs). Results: Our analysis included 17 RCTs (164,862 patients; 83,309 received aspirin and 81,744 received placebo). Our study did not demonstrate any significant reduction in all-cause mortality for patients treated with aspirin when compared with placebo (RR 0.97; 95% CI 0.93–1.01; P = 0.13). Sensitivity analysis performed by excluding healthy elderly (≥ 65) showed significant reductions in all-cause mortality in the aspirin-treated patients (RR 0.94; 95% CI 0.90–0.99; P = 0.01). There were no significant differences between both groups regarding cardiovascular mortality and cerebrovascular events (P > 0.05). However, aspirin-treated patients significantly reduced MACE and MI events (RR 0.89; 95% CI 0.85–0.93; P < 0.001 and RR 0.88; 95% CI 0.78–0.98; P = 0.02, respectively), respectively. However, aspirin was associated with a significantly higher incidence of bleeding, including major bleeding and intracranial bleeding (P < 0.001). Conclusions: Aspirin use in primary prevention has resulted in a lower incidence of MACE and MI without significantly effecting cerebrovascular events. However, aspirin was associated with a higher bleeding risk. Use of aspirin as a means of primary prevention should be thoroughly discussed with patients and pursued based on the risk of cardiovascular disease while also considering bleeding risk.