Rationale for a primary prevention study using low-dose aspirin to prevent coronary and cerebrovascular disease in...

The benefits of prophylactic aspirin therapy to prevent cardiovascular and cerebrovascular disease in asymptomatic individuals remains unclear. The rationale for developing a multicentered, double-blind, placebo-controlled clinical trial to determine whether low-dose aspirin (100 mg daily) prevents cardiovascular and cerebrovascular morbidity and mortality in persons aged 70 years and over with no evidence of pre-existing cardiovascular or cerebrovascular disease is described. Sample size calculations have indicated that 15,000 subjects would be required over a 4-year follow-up period in order to demonstrate a 20% reduction in overall cardiovascular mortality at the 0.01 level with a power of 0.8. Such a large-scale community-based clinical trial has never been conducted in Australia in this age group. Therefore the PACE (prevention by low-dose aspirin of cardiovascular disease in the elderly) pilot study has been developed to test recruitment strategies and methods and ascertaining disease end-points.