The accuracy of several bioelectrical impedance analysis (BIA) instruments for evaluating body composition in obese children is unknown. In obese and extremely obese children, researchers compared the relative accuracy of two BIA devices to dual x-ray absorptiometry (DXA). In cross-sectional research of 78 obese children, we used a portable single frequency tetrapolar BIA device (Omron), a stationary multifrequency octopolar BIA device, and DXA to evaluate body composition. Intraclass correlations paired t-tests, and Bland-Altman analyses were used to determine inter method agreement. DXA revealed that participants had a mean body mass index of 36.7 7.5 kg/m2, a body fat percentage of 46.4 percent 5.2 percent, and an appendicular lean mass of 22.5 6.0 kg. Body fat % intraclass correlations with DXA were 0.39 and 0.87 for single-frequency tetrapolar and multifrequency octopolar BIA devices, respectively. Body fat percentage was overestimated by 5.5 percent 2.9 percent using a single frequency tetrapolar BIA. The differences in body fat percentage and appendicular lean mass between the multifrequency octopolar BIA and DXA were modest, with 95 percent limits of agreement around 5%.

The relative accuracy of BIA devices in assessing body composition in obese and extremely obese children varies. In comparison to DXA, the multifrequency octopolar BIA device accurately assessed body fat % and appendicular lean mass and offers the benefit of point-of-care performance.