OBJECTIVES:To evaluate in peripheral arterial disease two strategies of antiplatelet therapy (clopidogrel and aspirin) in terms of number of ischemic stroke and hemorrhagic events, to estimate the losses of chances after no-choice of the most favorable strategy and the impact of these losses of chances in terms of days of hospitalizations, to estimate the cost-effectiveness ratio of the most effective and best tolerated strategy. METHOD:The number of patients to be treated to avoid one critical event (ischemic and hemorrhagic events) was calculated from the results of the annual rates established by the CAPRIE trial conducted in a population of French patients with peripheral arterial disease. This number of patients to treat was then extrapolated to the entire French population of peripheral arterial disease patients. The absolute numbers of critical events avoided with clopidogrel in France defined the losses of chances in the case of no-choice of this drug. Estimates in terms of days of hospitalization and cost-effectiveness ratio (in euro per life year gained) were based on data from the French Medical Information System. RESULTS:The number of patients to treat to avoid one ischemic event was 87 and the number of patients to treat to avoid one major hemorrhagic event was 149. In the peripheral arterial disease population, the numbers of ischemic and hemorrhagic events generated by non-treatment with clopidogrel was estimated at 3761 and 2191, respectively i.e. a total of 5952 events per year. These events included: 2025 myocardial infarctions, 1157 ischemic strokes, 579 deaths of vascular origin and 2191 digestive hemorrhages, requiring 60,394 hospitalization days. The cost-effectiveness ratio of clopidogrel was 10,393 euro per life year gained, and was much lower than commonly accepted cost-effective thresholds in Europe, which are around 30,000 euro per life year gained. CONCLUSION:The choice of clopidogrel in patients with peripheral arterial disease improves the prevention of subsequent events (ischemic and hemorrhagic events) with a cost-effectiveness ratio 2 to 3 times lower than the European thresholds accepted by the World Health Organization and avoids 1 day of hospitalization for 5.4 treated patients.