All cause mortality and body mass index in a young Asian occupational cohort without baseline metabolic syndrome components

Background: The aim was to investigate associations between underweight, overweight and obesity and all cause, cancer and cardiovascular disease (CVD) mortality, excluding subjects with known CVD, diabetes, hypertension and components of the metabolic syndrome (MetS) at baseline.Methods: The study population consisted of examinees participating in a health screening in Korea from 2002 to 2013. Data were analyzed in 162,194 subjects (in a retrospective cohort study design-median (interquartile range (IQR) follow-up 4.9 (1.8–8.5 years))). The outcomes were all cause mortality, cancer and CVD.Results: The mean (age range) and median age (IQR) at baseline were 36.9(20.0–85.3) and 35.2 (30.8–40.6) years. There were 436 deaths during follow-up. For men and women together, the fully adjusted HR for underweight and all cause mortality, cancer and CVD was 1.53 (95% CIs 1.06–2.20), 1.21 (95% CIs 0.68–2.14) and 1.34 (95% CIs 0.40–4.49) respectively. In contrast, the fully adjusted HR for overweight/obesity combined and all cause mortality was 0.77 (95%CIs 0.63–0.95) and there were non significant trends towards decreased cancer and CVD mortality. The association between overweight/obesity and all cause mortality was similar for men and women considered separately and for overweight and obesity as separate BMI categories. Smoking did not seem to explain the increased HR in the underweight BMI category.Conclusions: In a young metabolically healthy adult cohort, underweight was associated with increased all cause mortality and overweight/obesity was associated with decreased all cause mortality if CVD, diabetes, hypertension and components of the metabolic syndrome (MetS) are excluded