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Ability of biolectric impedance to predict fat-free mass in prepubertal children
J J Reilly1, J Wilson, J H McColl
1Department of Human Nutrition, University of Glasgow, United Kingdom.
Insights
Choosing the right body impedance (BI) equation is crucial for accurately estimating fat-free mass (FFM) in children. The Houtkooper et al. equation demonstrated the best predictive accuracy among four tested pediatric BI equations.
Area of Science:
- Pediatric health
- Body composition analysis
- Biometric measurement techniques
Background:
- Body composition measurements are increasingly utilized in pediatric care.
- Tetrapolar whole body impedance (BI) is a promising method for assessing body composition in children.
- Accuracy of BI in estimating pediatric fat-free mass (FFM) and the impact of different prediction equations remain unclear.
Purpose of the Study:
- To evaluate the accuracy of four published pediatric BI equations in predicting FFM.
- To compare the performance of different BI prediction equations in Caucasian prepubertal children.
- To identify the most reliable BI equation for pediatric body composition assessment.
Main Methods:
- Ninety-eight Caucasian prepubertal children (mean age 9.0 years) participated in the study.
- Four established pediatric BI equations were used to predict FFM.
- Predicted FFM values were compared against a reference method to assess accuracy and bias.
Main Results:
- Three of the four tested BI equations showed significant bias and wide limits of agreement.
- The equations by Cordain et al., Deurenberg et al., and Schaefer et al. either overestimated or underestimated FFM.
- The Houtkooper et al. equation exhibited negligible bias and narrower limits of agreement compared to the others.
Conclusions:
- The accuracy of BI for pediatric body composition prediction is highly dependent on the chosen equation.
- General applicability of BI equations across different pediatric populations cannot be assumed.
- Cross-validation of BI equations is recommended before routine use in children.
Abstract:
Measurements of body composition are being made increasingly widely in pediatrics. Tetrapolar whole body impedance (BI) is particularly suitable as a method of estimating body composition in children and is therefore the subject of great interest at present. However, the ability of BI to accurately estimate fat-free mass (FFM) in children is unclear, and users of BI are faced with a growing choice of prediction equations for estimation of FFM. Studies in adults have suggested that choice of prediction equation can have a profound effect on the estimate obtained. The aim of the present study was to measure the ability of four published pediatric BI equations to predict FFM in 98 Caucasian prepubertal children (mean age 9.0 y). For three of the published equations, limits of agreement between predicted and reference FFM were wide and distinct biases were apparent. With mean FFM of 25 kg, the equation of L. Cordain et al. overestimated reference FFM (95% CI +2.1 to +3.1 kg), whereas those of P. Deurenberg et al. (95% CI -1.9 to -2.9 kg) and F. Schaefer et al. (95% CI -1.4 to -2.5 kg) systematically underestimated reference FFM. The equation of Houtkooper et al. (95% CI -0.2 to +0.8 kg) predicted FFM with negligible bias and had narrower limits of agreement relative to the reference method than the other three equations tested. We conclude that the ability of BI to predict body composition in children depends on the equation chosen and that the general applicability of BI equations cannot be safely assumed. Cross-validation of BI equations is recommended before they are used routinely for estimation of body composition in children.