Bioimpedance in 7-Year-Old Children: Validation by Dual X-Ray Absorptiometry - Part 1: Assessment of Whole Body Composition

Aim: To validate the bioimpedance analyzer (BIA) Tanita BC-418 for its clinical and epidemiological use in children compared to dual-energy X-ray absorptiometry (DXA). Methods: A cross-sectional validation study was performed in 7-year-old children using anthropometry, BIA and DXA. Whole body fat and lean masses were assessed through BIA (BIA(outputs)) and DXA. Fat mass index (FMI) was calculated. Predictive equations were derived from raw impedance and anthropometric measures; results obtained from these predictive equations (BIA(regressions)) were also compared to DXA. Results: 171 children (84 boys) were studied. BIA(outputs) and DXA results revealed small differences for lean mass (1%) and moderate differences for fat mass (13%). BIA(regressions) results showed small differences for both body lean and fat masses (0.21 and 4.62%, respectively). Sensitivity and specificity to correctly classify children >90.8th percentile of FMI was 84.6 (64.3-94.9) and 95.9% (90.8-98.3) for BIA(outputs) and 100 (98.1-100.0) and 95.9% (92.3-99.4) for BIA(regressions), respectively. Conclusions: Tanita BC-418 may be valid for epidemiological studies assessing whole body composition. Its measurements may help in the diagnosis and monitoring of childhood overweight and obesity. The validation of predictive equations in specific populations may increase the precision of the technique. (C) 2013 S. Karger AG, Basel