Optimal cut-off points of weight for height, waist circumference and waist-to-height ratio for defining overweight and obesity in Thai school-aged children.

BACKGROUND The Body Mass Index (BMI) is widely used to diagnose overweight and obesity. However, there are limitations on the use of BMI and development of alternative measures can be of clinical importance. This study aimed to compare specificity and sensitivity of weight for height (W/H), waist circumference (WC) and waist-to-height ratio (WHTR) with BMI-for-age in diagnosing overweight and obesity in Thai school-age children. METHODS This was a cross-sectional study. Children between the ages of 6 and 13 who attended elementary schools were potential participants of the study. BMI, W/H, WC, and WHTR were calculated for each participant. The optimal cut-off points for the diagnosis of overweight and obesity by W/H, WC and WHTR were generated by the receiver operating characteristic curves (ROC). RESULTS Using BMI cut-off points introduced by WHO, the overall prevalence of overweight and obesity in the study population was 24.6% and 12.9% respectively. W/H, WC, and WHTR all showed acceptable sensitivity and specificity in diagnosing overweight and obesity when compared to BMI-for-age results. W/H had a particularly high correlation with BMI-for-age. CONCLUSION Cut-off points of 112% and 125% W/H are validated to determine overweight and obesity in Thai school-aged children.