Validation of Bioelectric Impedance Analysis against Dual-energy X-Ray Absorptiometry for Assessment of Body Composition in Indian Children Aged 5 to 18 Years.

Objective: To validate body composition measurements by Bioelectric Impedance Analysis (BIA) against Dual-Energy X-ray Absorptiometry (DXA) as the reference method in healthy children and adolescents.

Design: Cross-sectional.

Setting: Schools in and around Pune city, India.

Participants: A random sample of 210 (114 boys, 96 girls) apparently healthy Indian children and adolescents (5-18 y).

Methods: Weight, height, Tanner stage (TS) were recorded. Body composition measures: fat-free mass (FFM), fat mass (FM), lean mass (LM), bone mineral content (BMC) and body fat percentage (%BF) were assessed by BIA and DXA on a single day. Agreement between the methods was estimated by Pearson's correlation, and Bland and Altman analysis.

Main Outcome Measures: %BF, FM, FFM, LM, BMC.

Results: BIA underestimated %BF by 6.7 (3.7)% as compared to DXA. Mean FFM, BMC and LM by BIA were significantly higher than by DXA (P<0.001). These differences remained similar after adjusting for age, BMI and TS. Mean differences between FFM (-2.32 (1.39) kg), BMC (-0.18 (0.15) kg), and LM (-2.15 (1.34) kg) by DXA and BIA were significant (P<0.01). Correlations between BIA and DXA were 0.92 for %BF, 0.96 for LM and 0.98 for FFM and BMC. Both the methods were similar in identifying normal and overfat children as per their respective cut-offs.

Conclusion: BIA and DXA techniques are not interchangeable for assessment of body composition. However, BIA may be used in the field/clinical setting preferably with ethnicity specific references.