Higher mortality in metabolically obese normal‐weight people than in metabolically healthy obese subjects in elderly Koreans

OBJECTIVE: The purpose of this study was to investigate the impact of body mass index (BMI) and the presence of metabolic syndrome (MetS) on all-cause and cardiovascular mortality in elderly Korean men and women, and especially to compare metabolically obese normal-weight (MONW) and metabolically healthy obese (MHO) subjects. PATIENTS AND METHODS: A total of 2317 elderly people (over 60 years of age) were studied using follow-up data from the South-West Seoul (SWS) Study, a prospective cohort study. Mortality from all causes and cardiovascular disease (CVD) were evaluated according to the combination of the presence or absence of MetS and Asian-specific body mass index (BMI) criteria (BMI <23 kg/m²; normal weight, BMI 23-24·9 kg/m²; overweight, BMI ≥25 kg/m²; obesity). RESULTS: During a median follow-up of 10·3 years, 393 subjects died, including 126 from CVD. Among subjects with MetS, all-cause and CVD mortality were significantly higher in normal-weight subjects than overweight or obese individuals in Cox proportional-hazard models adjusted for confounding factors. Furthermore, among six groups with various MetS/BMI combinations, MONW individuals had the highest risk, whereas overweight subjects without MetS had the lowest risk of death from all causes and CVD [HR = 2·2 (95% CI = 1·4-3·4), HR = 3·0 (95% CI = 1·4-6·6) respectively]. Interestingly, all-cause mortality was significantly higher in MONW than MHO individuals. CONCLUSIONS: In contrast to MHO subjects, elderly individuals with the MONW phenotype exhibited greater all-cause mortality during 10 years of follow-up.