Reliability, Validity, and Diagnostic Value of a Pediatric Bioelectrical Impedance Analysis Scale

Area of Science:

• Pediatric Health
• Body Composition Analysis
• Biomedical Engineering

Background:

• Accurate body composition assessment is crucial for identifying overfat or obese children.
• Bioelectrical impedance analysis (BIA) offers advantages over BMI by distinguishing lean and fat mass.
• Previous BIA devices have shown questionable reliability and validity in pediatric studies.

Purpose of the Study:

• To evaluate the reliability, validity, and diagnostic accuracy of the Tanita BF-689 portable BIA scale.
• To assess the scale's suitability for use in the pediatric population.
• To compare BIA measurements with dual-energy X-ray absorptiometry (DEXA) in children.

Main Methods:

• Fifty-five children underwent two BIA assessments and one DEXA assessment for body fat percentage (%BF).
• Intraclass correlation coefficients (ICCs) were used to determine test-retest reliability.
• Convergent validity was assessed by comparing BIA and DEXA results using mean difference and limits of agreement.
• Sensitivity and specificity were calculated for classifying children as healthy, overfat, or obese.

Main Results:

• The BIA scale demonstrated excellent test-retest reliability with an ICC of 0.999.
• Agreement between BIA and DEXA for %BF was moderately strong (ICC = 0.788), with a mean difference of -6.75%.
• The scale showed high specificity for classifying children as overfat (0.78) and obese (1.0).

Conclusions:

• The Tanita BF-689 exhibits excellent test-retest reliability and acceptable agreement with DEXA for %BF assessment in children.
• The device is a reliable, valid, portable, and efficient tool for assessing body fat percentage in elementary school children.
• The scale demonstrates high specificity, making it valuable for identifying overfat and obese children.