Are Asians at greater mortality risks for being overweight than Caucasians? Redefining obesity for Asians

Objectives: To assess whether overweight Asians, assessed on the basis of WHO criteria, are at greater mortality risk than overweight Caucasians, and to determine whether alternative cut-off points BMI = 23-0-24-9 kg/m(2) for overweight and BMI >= 2 5 . 0 kg/m(2) for obesity) Suggested by the WHO Western Pacific Regional Office are appropriate. Design: The cohort was followed prospectively until the end of 2001. All-cause and CVD mortality risks of the overweight and Obese group, relative to the reference group (BMI = 18-5-24-9 or 18-5-22-9 kg/m(2)), were assessed using Cox regression analysis, adjusting for age, smoking and gender. Excess deaths were estimated with a method proposed by the US Centers for Disease Control and Prevention. Setting: National Health Interview Survey (NHIS 2001.) and a middle-aged perspective cohort in Taiwan. Subjects: Subjects comprised 36386 civil servants and school teachers, aged 40 years and older, who underwent a medical examination during 1989-1992. Results: In the WHO-defined overweight group, Asians showed a significant increase in all-cause mortality risk compared with Caucasians. Asians showed risks equivalent to Caucasians' at lower BMI (around 5 units). Every unit of BMI increase, at 25.0 kg/m(2) or above, was associated with a 9% increase in relative mortality risk from all causes. Applying a cut-off point of 25-0 kg/m2 for obesity would result a prevalence of 27.1%, while the traditional WHO cut-off point of 30.0 kg/m(2) yielded obesity prevalence of 4.1%. Excess deaths due to obesity accounted for 8.6% of all deaths and 21.1% of CVD deaths, based on the alternative cut-offs. Conclusions: In this Asian population, significant mortality risks started at 2 2.0 kg/m(2). The Study supports the use of BMI >= 25.0kg/m(2) rather than at BMI >= 30.0kg/m(2) BMI >= 25.0 kg/m(2) as a new cut-off point for obesity and BMI = 23.0-24.9kg/m(2) for overweight. The magnitude Of obesity-attributable deaths has been hitherto Under-appreciated among Asians.