Noncontraceptive estrogens and mortality: long-term follow-up of women in the Walnut Creek Study.

The effect of postmenopausal estrogen use on mortality is an important and controversial subject. To address it, we analyzed data from a ten- to 13-year mortality follow-up of the 3437 women enrolled in the Walnut Creek Contraceptive Drug Study who never used either estrogens or oral contraceptives and the 2656 women who used estrogens but not oral contraceptives. By 1983, 109 estrogen users and 110 nonusers had died. After adjusting for age, mortality in estrogen users (1.64 per 1000 woman-years) was lower than in nonusers (2.06 per 1000 woman-years) for all categories of cause of death except cancer. The lower mortality from accidents, suicide, and homicide in estrogen users has no plausible biologic explanation, and the observation suggests that life-style differences between estrogen users and nonusers account at least in part for their lower mortality. On the other hand, the observation that the relative risk of mortality due to cardiovascular disease was 0.5 in estrogen users, after adjustment for age and other cardiovascular disease risk factors, is suggestive.