Bioelectrical impedance analysis versus dual-energy X-ray absorptiometry for body composition assessment in children with chronic kidney disease.

INTRODUCTION

Children with chronic kidney disease (CKD) exhibit progressive body composition alterations. While dual-energy X-ray absorptiometry (DXA) is the reference standard, its routine use is limited by cost, radiation, and availability. Bioelectrical impedance analysis (BIA) offers a portable, radiation-free alternative, but its accuracy relative to DXA in paediatric CKD remains insufficiently evaluated.

METHODS

This cross-sectional study enrolled 102 children aged 5-14 years with CKD stages 3-5. Same-day BIA and DXA measurements were performed. Agreement between methods was assessed using Pearson's correlation coefficient, Lin's concordance correlation coefficient (CCC), and Bland-Altman analysis. Associations with CKD stage and sex were examined.

RESULTS

BIA showed strong to very strong correlations with DXA for fat mass (FM; r = 0.93), fat-free mass (FFM; r = 0.91), and total bone mineral content (BMC; r = 0.84). Lin's CCC indicated poor concordance for all parameters (all < 0.90): FFM 0.87, total BMC 0.81, total bone mineral density (BMD) 0.74, FM 0.66 and body fat percentage (BF%) 0.29. BIA systematically underestimated FM and overestimated FFM relative to DXA. DXA detected significant stage-wise reductions in FM, FMI, FFM and FFMI across CKD stages, whereas BIA detected only the decline in FFMI (p = 0.012).

CONCLUSIONS

Despite strong correlations, BIA showed poor concordance with DXA for every parameter assessed, with clinically unacceptable limits of agreement; correlation does not imply interchangeability. BIA may retain a role in population-level nutritional screening in resource-limited settings, although its ability to track change was not tested here; DXA remains necessary for individual-level assessment in paediatric CKD. What is known • Children with CKD experience progressive lean tissue loss, fat redistribution, and impaired bone mineralisation contributing to growth failure. • DXA is the reference standard for body composition assessment, but it is limited by cost, radiation, and availability. What is new • BIA shows a strong to very strong correlation with DXA but poor concordance (Lin's CCC < 0.90) for every body composition and bone parameter in paediatric CKD stages 3-5. • BIA cannot detect stage-wise differences in body composition that DXA identifies, limiting its diagnostic precision in this population.