[Consistency between bioelectrical impedance analysis and dual-energy X-ray absorptiometry in body composition measurement in children aged 6-17 years in China].

<b>Objective:</b> To evaluate the consistency between bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA) in the measurement of body composition in children aged 6-17 years in China. <b>Methods:</b> Fat-free mass, fat mass and fat mass percentage were measured by both BIA and DXA in 1 161 children. <i>t</i>-test or Wilcoxon paired test was used to evaluate the different outcome of the two methods. The correlation and consistency between the methods were evaluated by Spearman correlation coefficients (<i>r</i>) and Bland-Altman analysis. <b>Results:</b> Body compositions measured by BIA was positively correlated with those measured by DXA (fat mass <i>r</i>=0.95, fat-free mass <i>r</i>=0.98, fat mass percentage <i>r</i>=0.86, all <i>P</i><0.05). Comparing with DXA, BIA underestimate children's fat mass [the mean difference is -3.15 kg, and the <i>SD</i> is 2.35 kg, 95% limits of agreement (LoA): -7.74-1.45 kg] and fat mass percentage (the mean difference is -8.45%, and the <i>SD</i> is 4.63%, 95% LoA: -17.53%-0.64%). <b>Conclusions:</b> Body compositions measured by BIA was highly positively correlated with those measured by DXA. BIA has certain application value in the measurement of body fat mass and fat-free mass of children aged 6-17 years.