Body Composition in Children with Chronic Illness: Accuracy of Bedside Assessment Techniques

Abstract

Objective: To evaluate the accuracy of estimated fat mass and fat-free mass from bedside methods compared with reference methods in children with chronic illnesses.

Study design: Fat mass and fat-free mass values were obtained by skinfold, bioelectrical impedance analysis (BIA), dual-energy x-ray absorptiometry (DXA), and deuterium dilution method in children with spinal muscular atrophy, intestinal failure, and post hematopoietic stem cell transplantation (HSCT). Spearman's correlation and agreement analyses were performed between (1) fat mass values estimated by skinfold equations and by DXA and (2) fat-free mass values estimated by BIA equations and by DXA and deuterium dilution methods. Limits of agreement between estimating and reference methods within ±20% were deemed clinically acceptable.

Results: Fat mass and fat-free mass values from 90 measurements in 56 patients, 55% male, and median age of 11.6 years were analyzed. Correlation coefficients between the skinfold-estimated fat mass values and DXA were 0.93-0.94 and between BIA-estimated fat-free mass values and DXA were 0.92-0.97. Limits of agreement between estimated and DXA values of fat mass and fat-free mass were greater than ±20% for all equations. Correlation coefficients between estimated fat-free mass values and deuterium dilution method in 35 encounters were 0.87-0.91, and limits of agreement were greater than ±20%.

Conclusion: Estimated body composition values derived from skinfold and BIA may not be reliable in children with chronic illnesses. An accurate noninvasive method to estimate body composition in this cohort is desirable.

Keywords: bioelectric impedance analysis; body composition; bone marrow transplant; children; deuterium; dual x-ray absorptiometry; fat mass; fat-free mass; hematopoietic stem cell transplant; intestinal failure; isotope dilution; muscle; spinal muscular atrophy.

Conflict of interest statement

The authors declare no conflicts of interest.

Copyright © 2017 Elsevier Inc. All rights reserved.

Figures

Figure. Bland-Altman Plots- Agreement between Fat Mass (FM) FM and Fat Free Mass (FFM) estimating equations and Dual-Energy X-Ray Absorptiometry (DXA)

Dashed line represents the bias; Dotted lines represent the limits of agreement; Gray band represents the a priori determined clinically applicable +/− 20% limits of agreement A. FM estimated by the Brook equation versus FM determined by DXA (bias 13.38%, 95% LOA −38.13% to 64.9%); B. FM estimated by the Wendel 2 Skinfold equation versus FM determined by DXA bias −8.25%, 95% LOA −48.61% to 32.12%); C. FM estimated by the Wendel 4 skinfold equation versus FM determined by DXA (bias −9.34%, 95% LOA −46.88% to 28.2%); D. FFM estimated by the Deurenberg equation versus FFM determined by DXA (bias −2.77%, 95% LOA −25.49% to 19.96%); E. FFM estimated by the Houtkooper equation versus FM determined by DXA (bias −6.29%, 95% LOA −30.85% to 18.27%); F. FFM estimated by the Rush equation versus FM determined by DXA (bias −4.77%, 95% LOA −29.46% to 19.93%)