Role of Aspirin in the Primary Prevention of Cardiovascular Disease

Purpose: Aspirin is known to reduce cardiovascular disease (CVD) morbidity and mortality among survivors in a range of events, including myocardial infarction (MI) and stroke. In primary prevention, in patients who are healthy, the evidence of benefit to harm is not clear. We seek to summarize the most recent randomized controlled trials that have examined the role of aspirin in the primary prevention of CVD.

Materials and Methods: In the ARRIVE study, more than 12,000 men 55 years of age with 24 cardiovascular risk factors and women aged 60 years with three cardiovascular risk factors were randomly assigned to receive either 100 mg of aspirin daily or placebo. Results from this study reveal no difference in nonfatal MI as well as a composite score of CVD death, MI, unstable angina, stroke, or transient ischemic attack. In the ASCEND study in diabetes (ASCEND), more than 15,000 men and women with a history of diabetes were randomly assigned to receive either 100 mg of aspirin daily or placebo. Results from this study reveal a 12% reduction in nonfatal vascular events (relative risk [RR}, 0.88; 95% confidence interval [CI], 0.79–0.97; P = 0.01) counterbalanced by an increased risk of major bleeding (RR, 1.29; 95% CI, 1.09–1.52; P = 0.003). In the ASPREE study in the elderly (ASPREE), more than 19,000 healthy men and women were randomly assigned to receive with 100 mg of aspirin daily or placebo. Results from this study found no difference in MI or stroke (HR, 0.95; 95% CI, 0.83–1.08) but found a statistically significant increase in the risk of both intra and extracranial hemorrhage (HR, 1.38; 95% CI, 1.18–1.62; P <0.001) as well as, surprisingly, all-cause mortality (HR, 1.14; 95% CI, 1.01–1.29).

Results: ASCEND: Aspirin did not significantly reduce the risk of vascular death (2.7% vs. 2.9%; rate ratio, 0.93; 95% CI, 0.77–1.12). ARRIVE: There was no significant difference in the rates of cardiovascular death (HR, 0.97). ASPREE: For patients 70 years of age or older, the risk of fatal CVD was similar in the aspirin and placebo groups (1.8 vs. 1.9 events per 1000 person-years; HR, 0.97, 95% CI, 0.71–1.33).

Conclusions: After examining the most recent trials in regard to the role of aspirin in primary prevention of CVD, we must weigh the risks versus benefits and think twice before prescribing it to our patients.