Validity of Body Composition Estimates in Women Assessed by a Multifrequency Bioelectrical Impedance Device

Area of Science:

• Physiology
• Body Composition Analysis
• Biomedical Engineering

Background:

• Multifrequency bioelectrical impedance analysis (MF-BIA) devices like the InBody 770 (IB770) offer cost-effective and rapid body composition assessments.
• Validation against criterion methods is essential for establishing the accuracy of MF-BIA devices.

Purpose of the Study:

• To validate body composition measures from the IB770 against deuterium oxide dilution (D2O) and dual-energy X-ray absorptiometry (DXA).
• To compare a four-compartment (4C) model using IB770-derived total body water (TBW) with one using D2O-derived TBW.

Main Methods:

• Fifty-five adult females underwent IB770 and DXA scans, alongside the D2O dilution protocol.
• Agreement between IB770 and criterion measures (D2O, DXA) for fat mass (FM), fat-free mass (FFM), and TBW was assessed using Lin's concordance correlation coefficients (CCCs) and Bland-Altman analyses.
• Equivalence tests were employed to evaluate the agreement within 4C models.

Main Results:

• Substantial agreement was found between IB770 and D2O for TBW (CCC = 0.98).
• Excellent agreement was observed between IB770 and DXA for FM (CCC = 0.99).
• IB770 showed high agreement with DXA for FFM (CCC = 0.91), though it tended to overestimate FFM.
• Both 4C models demonstrated near-perfect agreement for FM, FFM, and body fat percentage (CCC = 0.99).

Conclusions:

• The IB770 device is a valid tool for assessing TBW in adult females.
• The IB770 can be effectively incorporated into 4C models for body composition assessment in this population.