The ARRIVE study was a LARGE randomised, double-blind, placebo-controlled, multicentre. Men aged 55 years and older or women 60 years or older and with moderate cardiovascular risk. Patients were randomly assigned (1:1) to receive enteric-coated aspirin 100 mg or placebo daily. The primary efficacy endpoint was a composite outcome of time to first occurrence of cardiovascular death, myocardial infarction, unstable angina, stroke, or transient ischaemic attack. Safety endpoints were haemorrhagic events and incidence of other adverse events, and were analysed in the intention-to-treat population. Median follow-up was 60 months, during which time the endpoint was observed in 269 (4·29%) patients in the aspirin group versus 281 (4·48%) patients in the placebo group (hazard ratio [HR] 0·96; 95% CI 0·81–1·13; p=0·6038). Gastrointestinal bleeding events (mostly mild) occurred in 61 (0·97%) patients in the aspirin group versus 29 (0·46%) in the placebo group (HR 2·11; 95% CI 1·36–3·28; p=0·0007). Serious adverse events were similar in treatment groups and treatment-related adverse events were not prominent (n=1050 [16·75%] for aspirin and n=850 [13·54%] for placebo . The number if deaths in each group was not different.

Unlike the case for secondary prevention, the evidence for aspirin as a strategy for primary prevention was not convincing. For more information about this study published in the Lancet, follow this link.