Prevention of serious vascular events by aspirin amongst patients with peripheral arterial disease : randomized, double-blind trial

OBJECTIVE: To assess the prophylactic efficacy of aspirin and a high-dose antioxidant vitamin combination in patients with peripheral arterial disease (PAD) in terms of reduction of the risk of a first vascular event (myocardial infarction, stroke, vascular death) and critical limb ischaemia. DESIGN: Randomized, placebo-controlled, double-blind clinical trial with 2 x 2 factorial design. SETTING: Thirty-seven European angiology/vascular medicine units. SUBJECTS: A total of 366 outpatients with stage I-II PAD documented by angiography or ultrasound, with ankle/brachial index <0.85 or toe index <0.6; 210 patients completed the follow-up. INTERVENTIONS: Four treatment groups: (i) oral aspirin (100 mg daily), (ii) oral antioxidant vitamins (600 mg vitamin E, 250 mg vitamin C and 20 mg beta-carotene daily), (iii) both or (iv) neither, given for 2 years. MAIN OUTCOME MEASURE: Major vascular events (cardiovascular death, myocardial infarction or stroke) and critical leg ischaemia. RESULTS: Seven of 185 patients allocated aspirin and 20 of 181 allocated placebo suffered a major vascular event (risk reduction 64%, P = 0.022); five and eight patients, respectively, suffered critical leg ischaemia (total 12 vs. 28, P = 0.014). There was no evidence that antioxidant vitamins were beneficial (16/185 vs. 11/181 vascular events). Neither treatment was associated with any significant increase in adverse events. Inclusion of this trial in a meta-analysis of other randomized trials of anti-platelet therapy in PAD makes the overall results highly significant (P < 0.001) and suggests that low-dose aspirin reduces the incidence of vascular events by 26%. CONCLUSIONS: For the first time direct evidence shows that low-dose aspirin should routinely be considered for PAD patients, including those with concomitant type 2 diabetes.