Aspirin for the primary prevention of stroke and myocardial infarction: ineffective or wrong dose?

A P P A C R G A N U F S A ore than 40 million Americans take aspirin for the primary or econdary prevention of myocardial infarction and stroke, inluding approximately half of all those aged 65 years or more. he daily dose varies from 81 mg (1 baby aspirin) to 325 mg 1 adult aspirin). The efficacy of aspirin for the secondary revention of myocardial infarction and stroke has been valiated by multiple randomized clinical trials. The first randomized clinical trial to establish the efficacy of spirin for primary prevention was the US Physicians Health tudy published in 1989. More than 22,000 male US physiians were randomized to 325 mg of aspirin every other day ersus placebo and followed for 5 years. The incidence of fatal r nonfatal myocardial infarction was 44% lower in those aking aspirin (odds ratio 0.56; 95% confidence interval, .45-0.70; P .0001). The decreased risk of myocardial inarction was present in those aged 50 years or more. There was o significant difference in mortality or stroke incidence. Multiple organizations and expert panels recommend spirin for the primary prevention of cardiovascular disease, s shown in Table 1. Three of the expert panels recommend daily dose of 100 mg or less, and one panel recomends a daily dose of 75 to 162 mg. However, the efficacy of aspirin for primary prevention ecently has been questioned. Three recent primary prevenion trials failed to demonstrate a decrease in either stroke or yocardial infarction. The Japanese Diabetes trial randomized 2359 men nd women with type 2 diabetes, aged 30 to 85 years mean 65 years), to 81 to 100 mg of aspirin per day versus o aspirin in an open-label trial. There was no significant ifference in the incidence of stroke or myocardial infarcion at the end of 4.4 years of follow-up. The Prevention of Progression of Arterial Disease and iabetes trial randomized 1276 men and women aged 40 ears or more (mean 60 years) with type 1 or 2 diabetes nd asymptomatic peripheral artery disease to 100 mg of spirin per day versus placebo. At the end of 6 to 7 years of ollow-up, there was no difference in the incidence of myoardial infarction or stroke.