Postmenopausal estrogen replacement: a long-term cohort study.

To assess the long-term effects of estrogen replacement therapy (ERT) in 157 postmenopausal women, a prospective, nonrandomized, cohort study was conducted from 1964 to 1989. ERT consisted of 0.625 mg of conjugated equine estrogen daily for the first 25 days of each month without oral progesterone from 1964 to 1984. From 1984 to 1989 5 mg of medroxyprogesterone was added from day 14 to 25 of every sixth month in subjects with an intact uterus. The mean loss of height was significantly less among the ERT subjects after age 65 years and remained at 0.08 cm/year from age 56 to 80 years, whereas the loss of height accelerated among the control subjects to 0.19 cm/year from age 66 to 70, to 0.22 cm/year from age 71 to 75, and to 0.30 cm/year from age 76 to 80. The mean cortical bone density at the distal third of the radius was significantly greater among the ERT subjects compared to the control subjects with the difference representing a 12.0% higher bone density with ERT. The risk of both vertebral compression and peripheral fractures was significantly reduced in the ERT group (relative risk 0.28). The mean serum LDL cholesterol was 21% lower and the mean HDL cholesterol, 37% higher among ERT subjects compared to control subjects. Both ERT and total serum cholesterol had independent effects on the development of cardiovascular disease (myocardial infarction and stroke) in a multivariate analysis.