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 over-weight 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 over-weight 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 over-weight and obesity in Thai school-aged children.