The Usefulness of InBody 720 and Anthropometric Measurement Compared with Dual- energy X-ray Absorptiometry as a Diagnostic Tool of Childhood Obesity

ABSTRACT

Background: Bioelectrical impedance analysis (BIA) is frequently used to diagnose obesity in clinical setting, but the usefulness of BIA in children is not become known accurately. We analyzed the usefulness of BIA and anthropometric measurement compared with Dual-energy X-ray absorptiometry (DXA) as a diagnostic tool of childhood obesity. Methods: 205 volunteer primary and middle school children were recruited. We measured weight and height, and analyzed the body composition by BIA and DXA. By paired t-test and Bland-Altman plots, mean difference and limit of agreement were calculated between DXA and BIA according to sex and age groups. Sensitivity and specificity were displayed with the gold standard of PBF above 35% by DXA. Results: There was significantly positive correlation between DXA and BIA in fat mass (FM) (r=0.982, P<0.001), fat free mass (FFM) (r=0.990, P<0.001), and percent body fat (PBF) (r=0.956, P<0.001). Mean difference between DXA and BIA in FM, FFM, and PBF were -0.4+/-1.4 kg (P<0.001), -0.6+/-1.3 kg (P<0.001), and 0.5+/-2.8% (P=0.016), respectively. Limit of agreement in FM, FFM, and PBF were -0.4+/-2.7 kg, -0.6+/-2.5 kg, and 0.5+/-5.5%, respectively. The most sensitive method of diagnosis of obesity was Korean BMI standards for 85 percentile (94.7%) and IOTF BMI 25 kg/m2 (94.7%). The sensitivity and specificity by BIA were 90.7% and 97.7%. Conclusions: BIA was not interchangeable with DXA. However because of higher diagnostic accuracy and correlation, it could be used to measure body composition as simple field method. We recommend Korean BMI standards for 85 percentile or IOTF BMI 25 kg/m2 as the screening test for diagnosis of Korean childhood obesity.