Waist circumference and waist-to-height ratio percentiles ofThai school-aged children

Introduction: Waist circumference (WC) and waist-to-height ratio (WHTR) are used to screen the central obesity and identify metabolic syndrome. These parameters are dependent on sex, age and ethnicity, thus requiring specific values in each country. The study aims to develop age and gender specific WC and WHTR percentile curves for Thai youth. Method: This is a cross-sectional study based on the nutrition survey of schoolhood Thai children. Height, weight and WC are measured among 1,877 children. Smoothed age- and gender- specific percentile curves of WC and WHTR are calculated by the LMS method. Results: WC increases with age in both genders and boys have higher WC than girls at each age. WHTR is similar between genders and tends to decrease with age. Conclusion: These reference curves represent the first WC and WHTR percentile for Thai children. We encourage the use of these values to evaluate central fatness in this population.