Efficacy and Safety of Prasugrel vs Clopidogrel in Thrombotic Stroke Patients With Risk Factors for Ischemic Stroke Recurrence: A Double-blind, Phase III Study (PRASTRO-III)

Aim: To examine the efficacy and safety of prasugrel vs clopidogrel in thrombotic stroke patients at risk of ischemic stroke. Methods: This multicenter, active-controlled, randomized, double-blind, double-dummy, parallel group study enrolled thrombotic stroke patients aged ≥ 50 years at risk of ischemic stroke. Patients received prasugrel (3.75 mg/day) or clopidogrel (75 or 50 mg/day) for 24–48 weeks; other antiplatelet drugs were prohibited. The primary efficacy endpoint was the composite incidence of ischemic stroke, myocardial infarction (MI), and death from other vascular causes from the start to 1 day after treatment completion or discontinuation. Secondary efficacy endpoints included the incidences of ischemic stroke, MI, death from other vascular causes, ischemic stroke and transient ischemic attack, and stroke. Safety endpoints included bleeding events and adverse events (AEs). Results: In the prasugrel (N=118) and clopidogrel (N=112; all received 75 mg) groups, the primary efficacy endpoint composite incidence (95% confidence interval) was 6.8% (3.0%–12.9%) and 7.1% (3.1%–13.6%), respectively. The risk ratio (prasugrel/clopidogrel) was 0.949 (0.369–2.443). Secondary efficacy endpoints followed a similar trend. The combined incidences of life-threatening, major, and clinically relevant bleeding were 5.0% and 3.5% in the prasugrel and clopidogrel groups, respectively. The incidences of all bleeding events and AEs were 19.2% and 24.6% and 76.7% and 82.5% in the prasugrel and clopidogrel groups, respectively. No serious AEs were causally related to prasugrel. Conclusions: We observed a risk reduction of 5% with prasugrel vs clopidogrel, indicating comparable efficacy. There were no major safety issues for prasugrel.