[Interchangeability of different indirect methods for determining body composition]

Determination of body composition components - muscle and fat mass - is an important step in clinical and epidemiological studies. The most common methods for quantitative determination of body composition are indirect methods. However, the variety of methods and models of devices used makes direct comparison of data at both group and individual levels difficult.

The aim of the study is to analyze the consistency of estimates of absolute values of fat and lean body mass, as well as the proportion of body fat mass, obtained using bioimpedance analyzers ABC-02 «Medas» (STC Medas, Russia), 770InBody (InBody, Korea) and ultrasound scanner BodyMetrix BX2000 (IntelaMetrix, USA) in a group of men and women.

An observational, single-center, cross-sectional, uncontrolled study was conducted. The main anthropometric characteristics (height and weight, waist circumference) were measured. Body composition was determined by bioimpedancemetry (BIA) using the octopolar scheme on the 770InBody device and the tetrapolar scheme on the ABC-02 Medass device and ultrasound scanning using the BodyMetrix BX2000 (BM) ultrasound scanner. The absolute (FM) and relative amount of body fat (PBF) and lean body mass were calculated.

A total of 48 people (38 women and 10 men) aged 24 to 74 years were examined. The anthropometric characteristics of the examined subjects were presented in a wide range. A strong correlation was found for all pairs of body composition components: the minimum value for the pair PBF ABC-BM was 0.853 [0.730, 0.913], the maximum was 0.988 [0.977, 0.993] for the pair FM ABC-InBody. Also, significant statistical differences (p<0.001) were found for all pairs of measurements, except for PBF determined by the BIA method. High agreement (CCC>0.95) of BIA estimates of the absolute amount of fat mass was shown, moderate agreement (CCC 0.9-0.95) is characteristic of the PBF determined by different BIA analyzers, and for all other pairs the agreement of measurements can be assessed as weak (CCC<0.90).

The best agreement at the group and individual levels was found for FM estimates by two different BIA analyzers (InBody and ABC).