Background: WHO Western Pacific Regional Office (WPRO) has proposed a redefined classification of weight according to body mass index (BMI) for Asian adults in 2000. The purpose of this study was to determine the optimal BMI cutoff points that correlate with the increased risk of obesity related disorders among the Korean population. The relationship between BMI and the
morbidity attributed to BMI-related diseases was examined by sex and age.
Methods: Korean National Health and Nutrition Examination Survey (KNAHNES) data from years 1998 to 2007 were used for this study. The data included physical examination reports, laboratory tests, and interviews of 23,671 adults. Receiver operating characteristic (ROC) curves were used to determine the optimal cutoff points between BMI and morbidity attributed to BMI-related diseases.
Results: The AUCs (Area Under the Curve) were highest when the optimal cutoff points of BMI were estimated using the morbidity of hypertension, DM or hypercholesterolemia. Using the morbidity of positively related diseases in both men and women, the optimal cutoff points of BMI in Korean adults were estimated to be 23.0~24.5 kg/m2 levels. The differences according to sex and age were not significant.
Conclusion: The optimal cutoff points of BMI in Korean adults estimated from this study were similar to the overweight criteria of WHO WPRO re-classification.
This study provides evidence to support the re-classification of BMI in Korean population.

Keywords: Body mass index, Obesity, ROC Curve, Korean National Health and Nutrition Examination Survey

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