Body Mass Index and Mortality in the General Population and in Subjects with Chronic Disease in Korea: A Nationwide Cohort Study (2002-2010)

PLOS ONE, Dec 2019

Background The association between body mass index (BMI) and mortality is not conclusive, especially in East Asian populations. Furthermore, the association has been neither supported by recent data, nor assessed after controlling for weight changes. Methods We evaluated the relationship between BMI and all-cause or cause-specific mortality, using prospective cohort data by the National Health Insurance Service in Korea, which consisted of more than one million subjects. A total of 153,484 Korean adults over 30 years of age without pre-existing cardiovascular disease or cancer at baseline were followed-up until 2010 (mean follow-up period = 7.91 ± 0.59 years). Study subjects repeatedly measured body weight 3.99 times, on average. Results During follow-up, 3,937 total deaths occurred; 557 deaths from cardiovascular disease, and 1,224 from cancer. In multiple-adjusted analyses, U-shaped associations were found between BMI and mortality from any cause, cardiovascular disease, and cancer after adjustment for age, sex, smoking status, alcohol consumption, physical activity, socioeconomic status, and weight change. Subjects with a BMI < 23 kg/m2 and ≥ 30 kg/m2 had higher risks of all-cause and cause-specific mortality compared with the reference group (BMI 23–24.9 kg/m2). The lowest risk of all-cause mortality was observed in subjects with a BMI of 25–26.4 kg/m2 (adjusted hazard ratio [HR] 0.86; 95% CI 0.77 to 0.97). In subgroup analyses, including the elderly and those with chronic diseases (diabetes mellitus, hypertension, and chronic kidney disease), subjects with a BMI of 25–29.9 kg/m2 (moderate obesity) had a lower risk of mortality compared with the reference. However, this association has been attenuated in younger individuals, in those with higher socioeconomic status, and those without chronic diseases. Conclusion Moderate obesity was associated more strongly with a lower risk of mortality than with normal, underweight, and overweight groups in the general population of South Korea. This obesity paradox was prominent in not only the elderly but also individuals with chronic disease.

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Body Mass Index and Mortality in the General Population and in Subjects with Chronic Disease in Korea: A Nationwide Cohort Study (2002-2010)

October Body Mass Index and Mortality in the General Population and in Subjects with Chronic Disease in Korea: A Nationwide Cohort Study (2002-2010) Nam Hoon Kim 0 1 2 Juneyoung Lee 0 1 2 Tae Joon Kim 0 1 2 Nan Hee Kim 0 1 2 Kyung Mook Choi 0 1 2 Sei Hyun Baik 0 1 2 Dong Seop Choi 0 1 2 Rodica Pop-Busui 0 1 2 Yousung Park 0 1 2 Sin Gon Kim 0 1 2 0 1 Division of Endocrinology and Metabolism, Department of Internal Medicine, Korea University College of Medicine , Seoul , Korea , 2 Department of Biostatistics, Korea University College of Medicine , Seoul , Korea , 3 Department of Statistics, Korea University , Seoul , Korea , 4 Division of Metabolism , Endocrinology , and Diabetes, Department of Internal Medicine, University of Michigan , Ann Arbor, MI , United States of America 1 Editor: Yan Li, Shanghai Institute of Hypertension , CHINA 2 Effects of BMI on Mortality Risk - Data Availability Statement: All relevant data underlying the findings of this study are currently included in the paper and its Supporting Information files. With respect to data availability, there were some restrictions to accessing the raw data. The data are available from the Korean National Health Insurance Service (NHIS), but access to confidential data is limited to researchers who meet the necessary criteria; basically, any researchers who propose a study subject and plans with standardized proposal form, and being approved by NHIS review committee of research support, can access the raw in East Asian populations. Furthermore, the association has been neither supported by recent data, nor assessed after controlling for weight changes. of more than one million subjects. A total of 153,484 Korean adults over 30 years of age without pre-existing cardiovascular disease or cancer at baseline were followed-up until body weight 3.99 times, on average. 1,224 from cancer. In multiple-adjusted analyses, U-shaped associations were found between BMI and mortality from any cause, cardiovascular disease, and cancer after adjustment for age, sex, smoking status, alcohol consumption, physical activity, socioeconomic status, and weight change. Subjects with a BMI < 23 kg/m2 and 30 kg/m2 had higher risks of all-cause and cause-specific mortality compared with the reference group (BMI 23–24.9 kg/m2). The lowest risk of all-cause mortality was observed in subjects with a data. Detailed process and a provision guide is now available at (http://nhiss.nhis.or.kr/bd/ab/ bdaba000eng.do). Funding: This study was supported by a grant of the Korean Health Technology R&D Project (HI14C1731), Ministry of Health & Welfare, Republic of Korea. The views expressed in this article are those of the authors and do not necessarily represent the official position of the department of Korean National Health Insurance Service. Competing Interests: The authors have declared that no competing interests exist. Abbreviations: BMI, body mass index; CVD, cardiovascular disease; WHO, World Health Organization; ICD, International Classification of Diseases; DM, diabetes mellitus; HTN, hypertension; CKD, chronic kidney disease; SES, socioeconomic status. BMI of 25–26.4 kg/m2 (adjusted hazard ratio [HR] 0.86; 95% CI 0.77 to 0.97). In subgroup analyses, including the elderly and those with chronic diseases (diabetes mellitus, hypertension, and chronic kidney disease), subjects with a BMI of 25–29.9 kg/m2 (moderate obesity) had a lower risk of mortality compared with the reference. However, this association has been attenuated in younger individuals, in those with higher socioeconomic status, and those without chronic diseases. Moderate obesity was associated more strongly with a lower risk of mortality than with normal, underweight, and overweight groups in the general population of South Korea. This obesity paradox was prominent in not only the elderly but also individuals with chronic disease. Introduction Obesity, generally defined by high body mass index (BMI), is closely associated with incident chronic disease including hypertension, type 2 diabetes and atherosclerotic cardiovascular diseases (CVDs) [1,2]. Previous studies have also shown that high BMI is related to an increased incidence of various types of cancers [3]. A logical assumption that overweight or obesity is associated with higher mortality than that of normal weight, however, is not conclusive. This ‘obesity paradox’ has been widely observed in different race or ethnic groups, and in patients with pre-existing chronic diseases such as hypertension, diabetes mellitus, heart failure, and chronic kidney disease [4–7]. Possible explanations for this paradox, mainly focusing on a study bias and confounding factors, include selection or survivorship bias, unintentional weight loss following chronic disease, treatment bias, and effects of major confounders including smoking status and age [8]. However, even after adjusting these major confounders, the obesity paradox still remains [9]. It has also been obser (...truncated)


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Nam Hoon Kim, Juneyoung Lee, Tae Joon Kim, Nan Hee Kim, Kyung Mook Choi, Sei Hyun Baik, Dong Seop Choi, Rodica Pop-Busui, Yousung Park, Sin Gon Kim. Body Mass Index and Mortality in the General Population and in Subjects with Chronic Disease in Korea: A Nationwide Cohort Study (2002-2010), PLOS ONE, 2015, 10, DOI: 10.1371/journal.pone.0139924