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

The role of aspirin as a means of primary prevention remains controversial.

We have conducted a meta-analysis of all randomized controlled trials (RCTs) to evaluate the role of aspirin in primary prevention.

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).

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).

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.