The Role of Estrogens as a Risk Factor for Stroke in Postmenopausal Women

The Collaborative Group for the Study of Stroke in Young Women and other similar studies linked oral contraceptives with increased risk of cardiovascular diseases. It is hypothesized that an increased risk for stroke should also be seen among postmenopausal women using estrogens as compared with nonusers. To test this hypothesis a total of 198 postmenopausal subjects most of whom were between 50 to 80 years of age and with a diagnosis of stroke during the period 1972 to 1974 were compared with 396 controls (those who had not had strokes) chosen randomly from the data bank of the Kaiser Foundation Health Plan. The 198 subjects were from the Northern California Kaiser Foundation Hospitals. Both groups were studied for estrogen use and for the associated risk factors of diabetes hypertension and coronary artery disease. Of those who had had strokes 20.7 percent had been taking estrogens compared to 18.4% in the control group (the difference was insignificant at Chi-Square=0.4396). Relative risk of stroke was calculated by the relative odds method to be 1.16 times as great in estrogen users as nonusers with 95% confidence limits of 0.75 and 1.77. Estrogen replacement therapy is beneficial for some postmenopausal women. Its risks and benefits must be carefully weighed. This study refutes the association between estrogen use in physiological replacement doses and increased risk of stroke in postmenopausal women.