Estrogen use and myocardial infarction risk: a case-control study.

A case-control study was conducted to examine the relationship of estrogen use to myocardial infarction in postmenopausal white women. After exclusion of proxy responses and of controls with discharge diagnoses of gynecologic or gallbladder diseases, there remained 39 matched sets (33 pairs and 6 triplets). The unadjusted relative odds ratio (RO) for past estrogen use was found to be 0.83. However, after simultaneous adjustment for cardiovascular diseases, smoking, education, and type of menopause, the net RO was 0.61. Type of menopause was found to interact with estrogen use, in that the protective effect was seen mainly in surgical menopause women, in whom the net RO for estrogen use was 0.37. Although none of the results reached statistical significance, they are consistent with recent results indicating a protective effect for estrogen therapy in regard to coronary heart disease, mainly among women undergoing surgical menopause.