Comparison of Prasugrel and Clopidogrel in Thrombotic Stroke Patients with Risk Factors for Ischemic Stroke Recurrence: An Integrated Analysis of PRASTRO-I, PRASTRO-II, and PRASTRO-III

INTRODUCTION: Patients with stroke are at a high risk of recurrence, and although they receive antiplatelet therapies such as clopidogrel for secondary prevention of non-cardioembolic stroke, the recurrence rate remains high. Three phase 3 trials (PRASTRO-I/II/III) were conducted to determine the efficacy of prasugrel in preventing recurrent stroke. Here, we performed an integrated analysis of these studies to confirm the generalizability of the PRASTRO-III findings and to supplement the small sample size of the study. METHODS: Patients from PRASTRO-I, PRASTRO-II, and PRASTRO-III with ischemic stroke (large-artery atherosclerosis or small-artery occlusion) and at least one of the following were included: hypertension, dyslipidemia, diabetes mellitus, chronic kidney disease, or ischemic stroke history. The primary efficacy endpoint was the composite incidence of ischemic stroke, myocardial infarction (MI), and death from other vascular causes in the intention-to-treat population. Bleeding events (life-threatening bleeding, major bleeding, and clinically relevant bleeding) were evaluated as the primary safety endpoint. Cumulative incidences and 95% confidence intervals (CIs) were calculated for the study outcomes using the Kaplan-Meier method. Hazard ratios (HRs) and 95% CIs were calculated using the Cox regression model. RESULTS: The data of 2,184, 274, and 230 patients from PRASTRO-I, PRASTRO-II, and PRASTRO-III, respectively, were analyzed (N = 2,688; prasugrel, N = 1,337; clopidogrel, N = 1,351). Stroke at enrollment was classified as large-artery atherosclerosis in 49.3% of patients and small-artery occlusion in 50.7% of patients. The primary efficacy endpoint composite incidence (prasugrel vs. clopidogrel) was 3.4% versus 4.3% (HR: 0.771, 95% CI: 0.522-1.138). The incidence of each component of the primary efficacy endpoint for prasugrel versus clopidogrel was 3.1% (n = 41) versus 4.1% (n = 55) for ischemic stroke, 0.3% (n = 4) versus 0.2% (n = 3) for MI, and no events of death from other vascular causes. For the primary safety endpoint, bleeding events were reported in 6.0% of patients in the prasugrel group versus 5.5% of patients in the clopidogrel group (HR: 1.074, 95% CI: 0.783-1.473). CONCLUSIONS: This integrated analysis supports the findings of PRASTRO-III. Prasugrel is a promising treatment that results in a numerical reduction in the composite incidence of ischemic stroke, MI, and death from other vascular causes in patients with ischemic stroke who are at a high risk of stroke recurrence. No major safety issues were observed for prasugrel.