Antiplatelet therapy reduces the risk of vascular death and nonfatal myocardial infarction (MI) and stroke in patients with unstable angina. At the time of this collaboration, however, there was uncertainty regarding a benefit for prolonged antiplatelet therapy in high-risk subpopulations, including patients with prior transient ischemic attacks (TIAs) or ischemic strokes. In a select population of patients, antiplatelet therapy had been demonstrated to be efficacious; however, the applicability to other demographics and the risk/benefit of long-term antiplatelet therapy among subjects at lower risk of occlusive vascular disease was unclear.

To evaluate the effects of antiplatelet therapy on nonfatal strokes, vascular deaths, or nonfatal MI in various patient populations.

Meta-analysis of 257 eligible randomized trials on antiplatelet therapy; analyzed until March 1990.