Randomised controlled trials (RCTs) that compared dipyridamole plus aspirin with aspirin alone were eligible for inclusion. Individuals with a previous history of ischaemic cerebrovascular disease or transient ischaemic attack were eligible for inclusion.
The primary outcome was a composite outcome of death from any vascular cause, non-fatal stroke and non-fatal myocardial infarction. The secondary outcomes included vascular death or non-fatal stroke, all death, vascular death, fatal and non-fatal stroke, and fatal and non-fatal myocardial infarction.
Pre-specified subgroup analyses for the primary outcome were: age (up to 65 years versus 65 years and over), gender, qualifying event (transient ischaemic attack versus stroke), type of vessel disease (small versus large), dose of aspirin (less than 75mg versus 75mg or more), formulation of dipyridamole (immediate versus extended release), time between event and randomisation (less than one week versus one week to one month versus one to six months) and history of hypertension, stroke, diabetes, or ischaemic heart disease. Subgroup analyses were also performed according to baseline risk with risk derived from two models based on different risk factors
The included trials used conventional-release or modified-release dipyridamole (daily dose 150mg to 400 mg) plus aspirin (daily dose ranged from 50mg to 990mg). The average age of included patients was 65 years; almost two-thirds were male.
Two reviewers selected trials for inclusion. It was unclear whether this was completed independently or how disagreements were resolved.