Conjugated Equine Estrogens and Coronary Heart Disease
February 2006
Findings Summary
The Women’s Health Initiative (WHI) Estrogen Alone trial differed from the better-known WHI trial of Estrogen plus Progestin in that it enrolled women who did not have a uterus, and who therefore did not need the progestin hormone. In the Estrogen Alone trial, 10,739 women with prior hysterectomy, aged 50-79 years, were assigned to conjugated estrogens (Premarin) 0.625 mg daily or to identical-appearing inactive pills. The study was stopped ahead of schedule in February 2004 by the National Institutes of Health because of increased stroke risk. During 7.1 years of follow up, estrogen provided no overall protection against heart attack or coronary death in generally healthy postmenopausal women most of whom were more than 10 years past menopause when they entered the study. In women 50-59 years of age at study entry, there was a suggestion of lower rates of heart attacks or procedures to re-open clogged arteries; these findings could be due to chance. There was no suggestion of benefit in women who were 60 years or older.