Age at menopause and cause-specific mortality in South Korean women: Kangwha Cohort Study

OBJECTIVE: The purpose of this study was to examine the relation between age at natural menopause and all-cause and cause-specific mortality among women. METHODS: This study used the data of the Kangwha Cohort that was followed up from 1985 to 2001, in particular, for the group of 55 years or older women (n=2658). We calculated the hazard ratio of mortality by the group of age at menopause using the Cox proportional hazards model with adjustment for age, alcohol consumption, education, age at first birth, self-cognitive health level, chronic disease, marital partner, parity, age at menarche, oral contraceptive use and hypertension. RESULTS: The mean (standard deviation) age at menopause was 46.9 (4.9) years, and the median age was 48 years. After adjusting for the relevant variables, the risk of total death in the early menopause group (<40 years at menopause) was 1.32 times higher than that of the reference group (45-49 years at menopause) (95% confidence interval [CI], 1.05-1.66, p=0.02). For the early menopause group, relative to the reference group, the adjusted hazard ratios of death due to cardiovascular disease and cancer were 1.53 (95% CI, 1.00-2.39, p=0.04) and 2.01 (95% CI, 1.06-3.82, p=0.03), respectively. CONCLUSION: Through this study, the age at menopause was found to be different between Asian and Caucasian women and the association of age at menopause with death, particularly caused by cardiovascular disease and cancer, was validated. Our study is one of rare studies regarding the age at menopause of Asian women and their risk of mortality, which could be considered to be meaningful.