218 Body composition estimation by bioelectrical impedance: Validation of an equation adapted to children with cystic fibrosis

Abstract

Objectives Nutritional status is an important factor which determines the respiratory outcome in cystic fibrosis (CF) patients. Body composition (BC), and more specifically fat free mass (FFM), impacts on respiratory function in adults; however data concerning pediatric cohorts are sparse. The gold standard method to estimate BC is dual X-Ray absorptiometry (DXA), but it is radiating, time consuming and frequently unavailable. Bioelectrical impedance analysis (BIA) is reproducible and easily feasible. Our objective is to validate an equation adapted to the pediatric CF population in order to calculate FFM by BIA. We also aim to investigate the correlation between BC and pulmonary function testing (PFT). Methods CF children and non-CF controls are evaluated prospectively using four-electrode multiple-frequency BIA (Aminostats Bio-ZM II). DXA (Hologic QDR 4500) is performed a few minutes later without modification of patients’ hydration status. Results of FFM obtained by BIA are compared to those calculated by DXA in order to validate the accuracy of the BIA equation. Correlation between FFM and PFT (FEV1, maximum inspiratory pressure) is also evaluated. Results The equation proves accurate in CF children. BC of CF patients is under evaluation and will be compared to that of controls matched for age and sex. Correlation between BC and PFT will be presented. Conclusion BIA is a helpful method to estimate BC. We have validated an equation adapted to the pediatric CF population. Repetitive measures of BC will allow clinicians to adjust nutritional care in order to improve the respiratory outcome of CF patients.