A Prospective Study of Postmenopausal Estrogen Therapy and Coronary Heart Disease

TLDR

The study aimed to determine whether postmenopausal estrogen use reduces coronary heart disease risk among nurses. A prospective cohort of 121,964 nurses was followed from 1976 with mailed questionnaires and medical record verification, achieving 92.7 % follow‑up to capture hormone use and coronary events. During 105,786 person‑years, estrogen users had a 50 % lower risk of coronary disease (RR 0.5) and current users a 70 % lower risk (RR 0.3), even after adjusting for major risk factors, supporting a protective effect of postmenopausal estrogen.

Abstract

To clarify the possible role of postmenopausal estrogen use in coronary heart disease, we surveyed 121,964 female nurses, aged 30 to 55 years, with mailed questionnaires, beginning in 1976. Information on hormone use and other potential risk factors was updated and the incidence of coronary heart disease was ascertained through additional questionnaires in 1978 and 1980, with a 92.7 per cent follow-up. End points were documented by medical records. During 105,786 person-years of observation among 32,317 postmenopausal women who were initially free of coronary disease, 90 women had either nonfatal myocardial infarctions (65 cases) or fatal coronary heart disease (25 cases). As compared with the risk in women who had never used postmenopausal hormones, the age-adjusted relative risk of coronary disease in those who had ever used them was 0.5 (95 per cent confidence limits, 0.3 and 0.8; P = 0.007), and the risk in current users was 0.3 (95 per cent confidence limits, 0.2 and 0.6; P = 0.001). The relative risks were similar for fatal and nonfatal disease and were unaltered after adjustment for cigarette smoking, hypertension, diabetes, high cholesterol levels, a parental history of myocardial infarction, past use of oral contraceptives, and obesity. These data support the hypothesis that the postmenopausal use of estrogen reduces the risk of severe coronary heart disease.