Relative Risks and Benefits of Long-Term Estrogen Replacement Therapy: A Decision Analysis

OBJECTIVE:To evaluate the relative risks and benefits of exogenous estrogen use among women entering the climacteric and to consider estrogen use for relief of symptoms or prevention of disease. METHODS:Decision analysis was used to assess the value of estrogen replacement therapy in a hypothetical cohort of 10,000 women assumed to be age 50 years; health outcomes were extrapolated to age 75. Risk ratios for mortality and morbidity of health outcomes associated with the use of estrogen replacement therapy were based on longitudinal studies reported in the literature. RESULTS:Estrogen use for 25 years would decrease fatal coronary heart disease events by 48% (567 cases), decrease deaths from hip fracture by 49% (75), increase deaths from breast cancer by 21% (39), and increase deaths from endometrial cancer by 207% (29 excess deaths). On balance, 25 years of estrogen replacement therapy in a cohort of 10,000 women would prevent 574 deaths. Further, women using estrogens for 25 years would gain 3951 quality-adjusted life years compared with women not using estrogens. Sensitiity analysis suggests that the benefits of estrogen replacement therapy outweigh the risks under most assumptions.