Objectives: This report presents information on the effects of aspirin on mortality, the occurrence of cardiovascular events, and the incidence of kidney disease in the patients enrolled in the Early Treatment Diabetic Retinopathy Study (ETDRS).
Study design: This multicenter, randomized clinical trial of aspirin vs placebo was sponsored by the National Eye Institute.
Patients: Patients (N = 3711) were enrolled in 22 clinical centers between April 1980 and July 1985. Men and women between the ages of 18 and 70 years with a clinical diagnosis of diabetes mellitus were eligible. Approximately 30% of all patients were considered to have type I diabetes mellitus, 31% type II, and in 39% type I or II could not be determined definitely.
Intervention: Patients were randomly assigned to aspirin or placebo (two 325-mg tablets once per day).
Main outcome measures: Mortality from all causes was specified as the primary outcome measure for assessing the systemic effects of aspirin. Other outcome variables included cause-specific mortality and cardiovascular events.
Results: The estimate of relative risk for total mortality for aspirin-treated patients compared with placebo-treated patients for the entire study period was 0.91 (99% confidence interval, 0.75 to 1.11). Larger differences were noted for the occurrence of fatal and nonfatal myocardial infarction; the estimate of relative risk was 0.83 for the entire follow-up period (99% confidence interval, 0.66 to 1.04).
Conclusions: The effects of aspirin on any of the cardiovascular events considered in the ETDRS were not substantially different from the effects observed in other studies that included mainly nondiabetic persons. Furthermore, there was no evidence of harmful effects of aspirin. Aspirin has been recommended previously for persons at risk for cardiovascular disease. The ETDRS results support application of this recommendation to those persons with diabetes at increased risk of cardiovascular disease.