RESUMO
This study compared the diagnostic quality of the body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR) in screening obesity among children, according to gender and maturation. A sample of 65 boys and 57 girls aged from 6.8 to 11.8 years underwent anthropometry and total percentages of body fat (%TBF)--the reference criterion--were obtained by skinfolds. Diagnostic quality was derived from the area under the ROC curve (AUC), sensitivity, specificity, accuracy, and Youden index (YI). In general, AUC ranged 0.80-1.00, with relatively higher values for WC in boys and late maturers. In the aforementioned subgroups, WC and WHtR were more sensitive than BMI. Furthermore, WC was more consistent in terms of the balance between sensitivity and specificity than BMI or WHtR, across gender and maturational status. The YI ranged 0.59-0.92 and 0.58-0.85 according to gender and maturational status, respectively. Higher values of YI were obtained with WC in boys and late maturers. BMI displayed better accuracy values (86.8-95.2%) among boys and early maturers. WHtR was least useful in classifying children's obesity status. Waist circumference exhibits an overall better performance, among boys and late maturers. Paediatricians should systematically add WC to clinical and epidemiological measurements.
