Adiposity assessments: Agreement between dual-energy X-ray absorptiometry and anthropometric measures in U.S. children

Objectives To evaluate performance of anthropometric measures relative to percentage body fat (%BF) measured by dual-energy X-ray absorptiometry in children. Methods Data from 8 to 19-year-old U.S. children enrolled in a nationally representative cross-sectional survey in 2001-2004 (n=5,355) with measured %BF, body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), and triceps skinfold thickness (TSF) were used. Agreement and prediction were evaluated based on standardized regression coefficients (β), kappa, and the area under the receiver-operating characteristic curves (AUC). Results The association between Z-scores for %BF and anthropometric measures was strong (β of ∼0.75-0.90, kappa of ∼0.60-0.75, and AUC of ∼0.87-0.98; P < 0.001 for all), with only some variations by race-ethnicity, mostly in girls. In boys, TSF and WHtR Z-scores had stronger agreement with %BF than BMI (β of 0.91 and 0.86 vs. 0.79, kappa of 0.75 and 0.71 vs. 0.59, and AUC of 0.97 and 0.97 vs. 0.91; P < 0.05 for all). In boys with BMI<median but %BF≥median, β value of TSF Z-score was higher than those from BMI. In girls, TSF also provided a higher agreement than BMI, but was only statistically higher for kappa. Conclusions High agreement and small racial-ethnic variations in the association between %BF and anthropometric measures support the use of anthropometric measures, especially WHtR and TSF, as proxy indicators for adiposity.