Objectives: The aim of this study was to evaluate the relation between lifetime estrogen exposure and mortality and compare this with menopausal age as exposure variable.
Methods: We studied a cohort of 1462 naturally postmenopausal women, aged 37-77 at enrollment in the Belgian Interuniversity Research on Nutrition and Health study. After a follow-up time of 10 years, 181 women had died, of whom 76 of cardiovascular causes. Logistic regression analysis was used to investigate the relations between lifetime estrogen exposure (calculated as menopausal age minus menarcheal age) and death as well as the relations between age at menopause and death.
Results: The risk of mortality was lower in women with a longer lifetime estrogen exposure as well as in women with higher menopausal ages. For women with a lifetime estrogen exposure of >or=40 years the odds ratio of all-cause mortality was 0.58 (95% confidence interval (CI) 0.35-0.93) compared to women who had a lifetime estrogen exposure of <or=33 years. Women who became menopausal after the age of 53 years had a similar reduction in mortality risk (odds ratio 0.62; 95% CI 0.36-1.03) when compared to women with menopausal ages of <or=46 years. These decreases in mortality risk were particularly due to a reduction in mortality of cardiovascular diseases.
Conclusions: This study indicates that menopausal age predicts mortality. The prediction is not improved by adding the age at menarche, to obtain an estimate for lifetime estrogen exposure.