Question: Is a history of pre-existing atherothrombotic disease associated with an increased risk of subsequent ischemic events, and is it associated with a reduction in efficacy of clopidogrel? Population: Patients with recent ischemic stroke (IS), myocardial infarction (MI), or established peripheral arterial disease, and a history of pre-existing symptomatic atherothrombotic disease (IS and=or MI) were enrolled in the Clopidogrel versus Aspirin in Patients at Risk of Ischemic Events (CAPRIE) trial. CAPRIE was a randomized, blinded, clinical trial comparing the efficacy of clopidogrel with aspirin in patients at risk of ischemic events.
Design and methods: Retrospective, subgroup analysis of 4496 patients with a prior history of symptomatic atherothrombotic disease from the CAPRIE study.
Results: Compared with the overall population of CAPRIE, patients with pre-existing symptomatic atherothrombotic disease have elevated rates of IS, MI, or vascular death. The 3-year rates of IS, MI, or vascular death were 20.4% with clopidogrel and 23.8% with aspirin (absolute risk reduction: 3.4%; 95% CI: -0.2 to 7.0; number needed to treat: 29; relative risk reduction: 14.9% (95% CI: 0.3 to 27.3; p = 0.045)). Conclusion: Patients with a history of previous symptomatic atherothrombotic disease suffer a high rate of subsequent ischemic events. Among these patients, the absolute risk reduction of clopidogrel over aspirin is greater compared with patients without pre-existing atherothrombotic disease.
