Effects of aspirin dose when used alone or in combination with clopidogrel in patients with acute coronary syndromes: observations from the Clopidogrel in Unstable angina to prevent Recurrent Events (CURE) study

Abstract

Background: We studied the benefits and risks of adding clopidogrel to different doses of aspirin in the treatment of patients with acute coronary syndrome (ACS).

Methods and results: In the Clopidogrel in Unstable angina to prevent Recurrent Events (CURE) trial, 12 562 patients with ACS using aspirin, 75 to 325 mg daily, were randomized to clopidogrel or placebo for up to 1 year. In this analysis, patients were divided into the following 3 aspirin dose groups: < or =100 mg, 101 through 199 mg, and > or =200 mg. The combined incidence of cardiovascular death, myocardial infarction, or stroke was reduced by clopidogrel regardless of aspirin dose, as follows: < or =100 mg, 10.5% versus 8.6% (relative risk [RR], 0.81 [95% CI, 0.68 to 0.97]); 101 to 199 mg, 9.8% versus 9.5% (RR, 0.97 [95% CI 0.77 to 1.22]); and > or =200 mg, 13.6% versus 9.8% (RR, 0.71 [95% CI, 0.59 to 0.85]). The incidence of major bleeding increased with increasing aspirin dose both in the placebo group (1.9%, 2.8%, and 3.7%, respectively; P=0.0001) and the clopidogrel group (3.0%, 3.4%, and 4.9%, respectively; P=0.0009); thus, the excess risk with clopidogrel was 1.1%, 1.2%, and 1.2%, respectively. The adjusted hazard ratio for major bleeding for the highest versus the lowest dose of aspirin was 1.9 (95% CI 1.29 to 2.72) in the placebo group, 1.6 (95% CI 1.19 to 2.23) in the clopidogrel group, and 1.7 (95% CI 1.36 to 2.20) in the combined group.

Conclusions: In patients with ACS, adding clopidogrel to aspirin is beneficial regardless of aspirin dose. Bleeding risks increase with increasing aspirin dose, with or without clopidogrel, without any increase in efficacy. Our findings suggest that the optimal daily dose of aspirin may be between 75 and 100 mg, with or without clopidogrel.