Rationale for a trial of low-dose aspirin for the primary prevention of major adverse cardiovascular events and vascular dementia in the elderly : aspirin in reducing events in the elderly (ASPREE)

Low-dose aspirin (acetylsalicylic acid) therapy has been shown to reduce the risk of vascular events and there is increasing evidence of its potential to reduce the rate of cognitive decline in the elderly. Adverse effects including gastrointestinal and intracranial haemorrhage may offset these benefits. The balance of risks versus benefits of aspirin for the primary prevention of cardiovascular disease and vascular dementia has not been established in the elderly. There is clearly a need to conduct a study in family practice to investigate whether routine use of low-dose aspirin for the primary prevention of cardiovascular disease and vascular dementia in the elderly is beneficial or harmful.Aspirin in reducing events in the elderly (ASPREE) is a placebo-controlled trial of low-dose aspirin for the primary prevention of major adverse cardiovascular events and vascular dementia. It will follow 15 000 subjects aged 70 years or more for an average of 5 years. This sample size has a power of 87% to detect a 15% reduction in primary events in the aspirin group, with an anticipated combined primary event rate of 20 per 1000 patient years.The effects of low-dose aspirin (acetylsalicylic acid) on cardiovascular outcomes have been tested in randomised primary and secondary prevention trials. Meta-analyses of the primary prevention studies have shown that in the predominantly middle-aged male patient groups studied, aspirin therapy reduces the subsequent incidence of cardiovascular death, non-fatal myocardial infarction and non-fatal stroke.[1,2]The available data have been drawn from five major morbidity/mortality trials, whose participants were predominantly middle- aged males (table I).[3-7]Amongst such individuals, the proportional reduction in vascular risk has been similar to that found in secondary prevention trials.[8,9]However, the absolute benefit to be gained from aspirin is generally less in primary prevention and therefore the trade-off between the benefits of reduced vascular risk and the burden of adverse effects is more finely balanced.[1]Unlike secondary prevention, no primary prevention study has yet identified a benefit in terms of all-cause mortality.