ESTROGEN REPLACEMENT THERAPY AND MORTALITY AMONG OLDER WOMEN - THE STUDY OF OSTEOPOROTIC FRACTURES

Background: Most previous studies of estrogen replacement therapy (ERT ) and mortality have focused on younger women, Recently, it has been s uggested that the effect of ERT on mortality may represent a ''healthy -user'' effect, ie, those with healthier lifestyles having a greater l ikelihood of receiving ERT. Methods: Nine thousand seven hundred four women, 65 years or older, participated; 1258 (14.1%) reported current use of ERT for at least 1 year at entry. During an average follow-up o f 6.0 years, 1054 women (11.8%) died. Results: After adjusting for mul tiple variables, mortality rate was lower among current (relative risk [RR], 0.69; 95% confidence interval [CI], 0.54-0.87) and past users ( RR, 0.79; 95% CI, 0.66-0.95), mainly due to reductions in deaths due t o cardiovascular disease. The protective effect of ERT was greatest am ong women younger than 75 years (RR, 0.55; 95% CI, 0.40-0.76) compared with women from 75 to 84 years of age (RR, 0.93; 95% CI, 0.62-1.41) a nd 85 years or older (RR, 1.33; 95% CI, 0.43-4.12). The RR for overall mortality was 0.95 (95% CI, 0.68-1.32) among short-term users (1-9 ye ars) compared with 0.55 (95% CI, 0.40-0.75) among long-term users (gre ater than or equal to 10 years). Deaths considered unrelated to ERT te nded also to be reduced in current users younger than 75 years (RR, 0. 72; 95% CI, 0.49-1.06) and current long-term users (RR, 0.75; 95% CI, 0.51-1.10). Conclusions: Estrogen replacement therapy is associated wi th lower overall mortality rates and reduced deaths due to cardiovascu lar disease. Women using ERT had healthier lifestyles, and the risk fo r death thought to be unrelated to ERT also tended to be lower in ERT users, suggesting in part a healthy-user effect.