BODY COMPOSITION IN MOROCCAN CHILDREN USING ISOTOPE DILUTION: DEVELOPMENT AND VALIDATION OF BIOELECTRICAL IMPEDANCE ANALYSIS EQUATIONS FOR PREDICTION TOTAL BODY WATER AND FAT-FREE MASS

Background and objectives: Body composition is important as a marker of both current anf future health. Bioelectrical impedance analysis (BIA) is a simple and accurate method for estimating body composition, but requires population-specific prediction equations. The aim of the present study was to examine the validity of published BIA equations for assessing total body water (TBW) and fat-free mass (FFM) using deuterium oxide dilution (D2O) as the reference method and to develop new FFM-BIA and TBWBIA equations in Moroccan children. Methods: Data were collected from 250 healthy children aged 8-11 year-old. BIA variables were measured by a tetra-polar device. TBW and FFM were assessed by the D2O. The participants were sorted by gender and randomly split into development and validation subgroups. The validity of other published equations was also tested using Bland and Altman procedure, proportional bias and pure error. Results: Prediction equations were generated, incorporating height, impedance index, weight, age and sex as predictors (R2=0.91). The new equations provided non-significant proportional bias values, and better agreement than other tested equations. Bias and pure error values were -0.17 and 2.47 l for boys and -0.04 and 2.46 l for girls, for TBW equation. For FFM equation, bias values were 0.14 and -0.12 kg, and pure errors were 3.25 and 2.92 kg for boys and girls, respectively. Conclusions: The new BIA prediction equations have high accuracy on Moroccan children and are recommended for use in these populations.