Overall and abdominal obesity and risks of all-cause and cause-specific mortality in Korean adults: a pooled analysis of three population-based prospective cohorts
Authors and Affiliations
Authors and Affiliations
Hajin Jang,1 Rockli Kim,1,2 Jong-Tae Lee,1,2 Dong Hoon Lee,3 Edward L. Giovannucci3,4 and Hannah Oh1,2*
1Interdisciplinary Program in Precision Public Health, Department of Public Health Sciences, Graduate School of Korea University, Seoul, Republic of Korea
2Department of Health Policy and Management, College of Health Sciences, Korea University, Seoul, Republic of Korea
3Department of Nutrition, T.H. Chan Harvard School of Public Health, Boston, MA, USA
4Department of Epidemiology, T.H. Chan Harvard School of Public Health, Boston, MA, USA
*Corresponding author: Hannah Oh
Background: Studies found a J-shaped association between body mass index (BMI) and mortality. However, it is unclear whether the association is driven by biases, particularly confounding by fat-free mass.
Methods: We conducted an individual-level pooled analysis of three cohorts of Korean adults (aged ≥ 40 years; n = 153 248). Mortality was followed up through December 2019. Anthropometric data were directly measured at baseline. Fat and fat-free mass were predicted using validated prediction models. Using Cox proportional hazards models, we estimated the associations of BMI and waist circumference (WC) with all-cause and cause-specific mortality. To account for biases, we excluded participants aged ≥ 70 years, deaths that occurred within 5 years of follow-up and ever smokers, and adjusted for fat-free mass index (FFMI).
Results: During the follow-up of up to 18 years, 6061 deaths were identified. We observed J-shaped association of BMI (nadir at 22-26) and monotonically positive association of WC with all-cause, cardiovascular, and cancer mortality among Korean adults without a history of cancer or cardiovascular disease. In the BMI analysis, excluding ever smokers and adjusting for FFMI attenuated the excess mortality in underweight participants and transformed the J-shaped association into a monotonically positive shape, suggesting an increased mortality at BMI > 22.0. Excluding participants aged ≥ 70 years and deaths that occurred within 5 years of follow-up did not change the results. In the WC analysis, the monotonic positive associations did not change after the control. Similar results were observed among participants with a history of cancer or cardiovascular disease.
Conclusions: Our data suggest that both overall and abdominal body fat are associated with increased mortality in Korean adults