Estrogen use and all-cause mortality. Preliminary results from the Lipid Research Clinics Program Follow-Up Study

The association of exogenous estrogen use and hysterectomy status with all-cause mortality was examined in 2,269 white women, aged 40 to 69 years, who had been followed up for an average of 5.6 years in the Lipid Research Clinics Program Follow-up Study. A total of 72 deaths occurred during this period. The relative risk of death in estrogen users compared with nonusers was 0.54 in gynecologically intact women, 0.34 in hysterectomized women, and 0.12 in bilaterally oophorectomized women. The risk of death in estrogen users, irrespective of hysterectomy status, was 0.37 times that in nonusers (3.4/1,000 v 9.3/1,000). The significant negative association of estrogen use with mortality persisted after multivariate adjustment for confounding factors. Hysterectomy status alone was not a significant predictor of death. Some, but not all, of the lower risk of mortality in estrogen users can be accounted for by increased levels of high-density lipoprotein cholesterol.