Objective
To evaluate the accuracy of estimated fat mass (FM) and fat free mass
(FFM) from bedside methods compared with reference methods in children with
chronic illnesses.
Study design
FM and FFM values were obtained by skinfold (SF),
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. Spearman’s correlation and agreement analyses were
performed between a) FM values estimated by SF equations and by DXA; and b)
FFM values estimated by BIA equations and by DXA and deuterium dilution
methods. Limits of agreement (LOA) between estimating and reference methods
within +/− 20% were deemed clinically
acceptable.
Results
FM and FFM values from 90 measurements in 56 patients, 55%
male and median age 11.6 years. Correlation coefficients between the
SF-estimated FM values and DXA were 0.93–0.94 and between
BIA-estimated FFM values and DXA were 0.92–0.97. Limits of agreement
between estimated and DXA values of FM and FFM were greater than
±20% for all equations. Correlation coefficients between
estimated FFM values and deuterium dilution method in 35 encounters were
0.87–0.91, and LOA were greater than ±20%.
Conclusion
Estimated body composition derived from skin fold and BIA may not be
reliable for children with chronic illnesses. An accurate noninvasive method
to estimate body composition in this cohort is desirable.