Waist Circumference and Mortality in Korea: Evidence from the National Health Insurance Health Checkup 2009-2015

Background: Higher waist circumference (WC) is positively associated with increased mortality; therefore, we examined the relationship between WC and mortality in Korean populations with the interaction of body mass index (BMI) and WC for mortality. Methods: A total of 23,263,878 subjects who were older than 20 years and underwent the National Health Insurance Service health checkup were included. WC was divided into six categories by 5 cm increments and level 3 (85-90 cm in men and 80-85 cm in women) was referenced. Multivariable Cox proportional hazard models were used to obtain the hazard ratios (HRs) and 95% confidence intervals for all-cause mortality according to the six levels of WC. Findings: WC in 5 cm increments showed a positively increased all-cause mortality after adjusting for all covariates including BMI. Men showed higher HRs for mortality than women as WC increased, and the HRs were higher in the lower WC levels, but lower in the higher WC levels among the subjects aged 65–85 years than subjects aged 40–65 years. Even in subjects with normal weight and overweight, increased WC (levels 4, 5, and 6) showed increased HRs for mortality (HRs = 1·156, 1·412, and 1·614 in normal BMI and 1·145, 1·401, and 1·909 in overweight, respectively). Interpretation: This study provides evidence of the need to lose WC in the subjects with normal or overweight BMI categories. The importance of assessing WC routinely should be raised and the guidelines to keep proper WC are stressed. Funding Statement: We would like to thank the Korean National Health Insurance Corporation and all the participants of the study and health check-up. This study was supported by grant HC16C2285 from the Korean Health Technology and Research and Development project, Ministry of Health and Welfare, Republic of Korea. This research was also supported by a grant of the Development of an Interactive Medical History Taking Software (2017-0-00588), funded by the Ministry of Science and ICT, Republic of Korea Declaration of Interests: The authors have nothing to disclose. Ethics Approval Statement: The study protocol was approved by the Institutional Review Board of the Korea University Anam Hospital (ED17115) and permission for the use of health checkup data was granted by the NHIS (NHIS-2018-1-035).