The prevention of progression of arterial disease and diabetes (POPADAD) trial: factorial randomised placebo controlled trial of aspirin and antioxidants in patients with diabetes and asymptomatic peripheral arterial disease.

Objective: To determine whether aspirin and antioxidant therapy, combined or alone, are more effective than placebo in reducing the development of cardiovascular events in patients with diabetes mellitus and asymptomatic peripheral arterial disease.

Design: Multicentre, randomised, double blind, 2x2 factorial, placebo controlled trial.

Setting: 16 hospital centres in Scotland, supported by 188 primary care groups.