Evaluation of Five Bioelectrical Impedance Analysis Equations Against Air-Displacement Plethysmography in an Eastern European Population

Bioelectrical impedance analysis (BIA) is a widely used and an easy-to-apply method for determining body composition. However, its accuracy depends on population-specific equations. The aim of the present study is to identify the most appropriate fat-free mass (FFM) prediction equation for an Eastern European population using air-displacement plethysmography (ADP) as the reference method. The study group included 101 Caucasian subjects (56 women and 45 men) with an average body mass index (BMI) of 25.37 ± 5.45 kg/m2. One set of FFMBIA values was automatically calculated with the analyzer (Maltron BioScan 920-2), and four others were computed using the published equations of Kyle, Kanellakis, Heitman, and Deurenberg. The results were compared to FFMADP values measured using a BOD POD Gold Standard Body Composition Tracking System by Bland–Altman analysis. The smallest bias was obtained with the equation by Deurenberg, which underestimated FFM by only −0.22 ± 4.52 kg. The largest bias was obtained with the equation by Kyle (5.92 ± 4.73 kg), followed by the formula of Kanellakis (3.04 ± 4.65 kg). The equations by Heitman and the Maltron inbuilt formula overestimated FFM by 2.15 ± 4.27 kg and, respectively, 1.95 ± 4.3 kg. Although Maltron’s automatically generated values were very strongly correlated with ADP results (CCC = 0.93, SEE = 4.7), the formula by Deurenberg provided the most reliable estimates in the studied population.