Women in the aspirin group had a statistically non-significant 18% reduced risk of the primary study endpoint of visually-significant AMD (111 cases in the aspirin group vs 134 cases in the placebo group; hazard ratio [HR], 0.82; 95% confidence interval [CI], 0.64−1.06) (Table 2). For advanced AMD, there was a statistically non-significant 10% reduced risk in the aspirin group (26 cases in the aspirin group vs 29 cases in the placebo group; HR, 0.90; CI, 0.53−1.52). When we considered all cases of AMD with or without vision loss, 302 cases were documented in the aspirin group and 291 in the placebo group (HR, 1.03, CI, 0.88 to 1.21). Cumulative incidence rates of visually significant AMD according to the year of follow-up are shown in Figure 2. The curves appeared to separate at around 3 years of follow-up, but never attained statistical significance.

The WHS was a randomized, double-blind, placebo-controlled, 2 × 2 factorial trial testing low-dose aspirin (100 mg every other day) and vitamin E in the primary prevention of cardiovascular disease and cancer among 39,876 female health professionals aged 45 years or older (30, 31). A third component, beta carotene, was terminated early in January 1996 after a median treatment duration of 2.1 years (32, 33). Baseline information included height, weight, history of cigarette smoking, history of alcohol use, blood pressure level, cholesterol level, history of diabetes mellitus, history of multivitamin use, parental history of myocardial infarction, postmenopausal hormone use, and history of an eye exam in the last 2 years. Information on a personal history of AMD was also obtained at baseline. A total of 39,876 women were randomized in blocks of 16 within 5-year age strata to aspirin (n=19,934) or placebo (n=19,942) using computer-generated random numbers. A total of 39,421 women were without a diagnosis of AMD at baseline and are included in these analyses:19,716 were in the aspirin group and 19,705 were in the placebo group (Figure 1). Informed consent was obtained from all participants, and the research protocol was reviewed and approved by the institutional review board at Brigham and Women's Hospital in Boston. This trial is registered at clinicaltrials.gov (NCT00000161).