PRIOR AND CURRENT HEALTH CHARACTERISTICS OF POSTMENOPAUSAL ESTROGEN REPLACEMENT THERAPY USERS COMPARED WITH NONUSERS

OBJECTIVE: Our purpose was to investigate whether selection of healthy women for postmenopausal estrogen therapy may confound observational studies of estrogen use and cardiovascular disease risk. STUDY DESIGN: Data were obtained from baseline (1981 to 1984) and follow-up (1990 t o 1992) health surveys of two cohorts randomly selected from communiti es in southeastern New England. At follow-up postmenopausal women grea ter than or equal to 40 years old were categorized as current users (n = 70) or nonusers (n = 772) of noncontraceptive estrogens. Users and nonusers were compared on both prior characteristics from the baseline surveys and current characteristics measured at follow-up by use of a nalysis of covariance. RESULTS: Prior levels of total and high-density lipoprotein cholesterol, body mass index, and blood pressure were sim ilar for estrogen users and nonusers. Estrogen users were less likely to have smoked and more likely to have had their cholesterol checked a nd to exercise regularly. These differences were more pronounced for c urrent characteristics than for baseline characteristics. CONCLUSIONS: Selection of healthy women for treatment may not fully explain the ap parent protective effect of estrogen replacement on cardiovascular ris k. However, more healthy profiles among estrogen users may inflate the apparent benefit of treatment in observational studies.