Prospective, randomised controlled trials (RCTs) that assessed the effects of aspirin therapy for the primary prevention of cardiovascular events in patients with diabetes mellitus were eligible for inclusion. To be included, trials had to have a follow-up duration of at least 12 months and report data on major cardiovascular events (a composite of cardiovascular mortality, non-fatal myocardial infarction or non-fatal stroke), myocardial infarction, stroke, all-cause mortality, cardiovascular mortality, or major bleeding.
Included trials compared aspirin monotherapy to placebo. Aspirin doses ranged from 50mg/day to 650mg/day. The mean age ranged between 60 to 64 years (where reported). The proportion of men ranged from zero to 100%.
The authors did not state how many reviewers selected studies for inclusion.