Validation of rapid 4-component body composition assessment with the use of dual-energy X-ray absorptiometry and bioelectrical impedance analysis

Abstract

Background The 4-component (4C) model is a criterion method for human body composition that separates the body into fat, water, mineral, and protein, but requires 4 measurements with significant cost and time requirements that preclude wide clinical use. A simplified model integrating only 2 measurements - dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) - and 10 min of patient time has been proposed. Objective We aimed to validate a rapid, simplified 4C DXA + BIA body composition model in a clinical population. Design This was a cross-sectional observational study of 31 healthy adults. Participants underwent whole-body DXA, segmental BIA, air displacement plethysmography (ADP), and total body water (TBW) measurement by deuterium (D 2 O) dilution. 4C composition was calculated through the use of the Lohman model [DXA mineral mass, D 2 O TBW, ADP body volume (BV), scale weight] and the simplified model (DXA mineral mass and BV, BIA TBW, scale weight). Accuracy of percentage of fat (%Fat) and protein measurements was assessed via linear regression. Test-retest precision was calculated with the use of duplicate DXA and BIA measurements. Results Of 31 participants, 23 were included in the analysis. TBW BIA showed good test-retest precision (%CV = 5.2 raw; 1.1 after outlier removal) and high accuracy to TBW D2O [TBW D2O = 0.956∗TBW BIA, R 2 = 0.92, root mean squared error (RMSE) = 2.2 kg]. %Fat estimates from DXA, ADP, D 2 O, and BIA all showed high correlation with the Lohman model. However, only the 4C simplified model provides high accuracy for both %Fat (R 2 = 0.96, RMSE = 2.33) and protein mass (R 2 = 0.76, RMSE = 1.8 kg). %Fat precision from 4C DXA + BIA was comparable with DXA (root mean square-SD = 0.8 and 0.6 percentage units, respectively). Conclusions This work validates a simplified 4C method that measures fat, water, mineral, and protein in a 10-min clinic visit. This model has broad clinical application to monitor many conditions including over/dehydration, malnutrition, obesity, sarcopenia, and cachexia.