Endogenous Estrogen Exposure and Cardiovascular Mortality Risk in Postmenopausal Women

Abstract

In this study, the authors investigated whether combined information on reproductive factors has additive value to the single reproductive factor age at menopause for assessing endogenous estrogen exposure and cardiovascular mortality risk in postmenopausal women. They conducted a population-based cohort study that included 9,450 postmenopausal women from Nijmegen, the Netherlands, who were aged 35--65 years at enrollment in 1975, with a median follow-up of 20.5 years. A Cox proportional hazards model and Receiver Operating Curves were used to analyze the data. Women aged 52 years or more at menopause had an 18% reduction in cardiovascular mortality (hazard ratio = 0.82, 95% confidence interval (CI): 0.69, 0.98) compared with those aged 44 years or less. Women with more than 18 years of exposure to endogenous estrogen had a statistically significant 20% reduction in cardiovascular mortality (hazard ratio = 0.80, 95 percent CI: 0.67, 0.96) compared with those who had 13 years of exposure or less. The area under the curve of the Receiver Operating Curves for the two models was identical (area under the curve = 0.67, 95 percent CI: 0.66, 0.68). This study shows that age at menopause is related to cardiovascular disease mortality and that a newly developed composite measure of endogenous estrogen exposure does not add to the predictive value of age at menopause for cardiovascular mortality.