Agreement between supine and standing bioimpedance spectroscopy devices and dual-energy X-ray absorptiometry for body...

Research comparing bioimpedance spectroscopy (BIS) to dual-energy X-ray absorptiometry (DXA) is limited, especially with newer BIS devices that take measures in a standing position instead of the traditional supine position.

The purpose of this study was to compare a standing BIS device (BIS_STA ) and a supine BIS device (BIS_SUP ) to DXA for measuring body fat percentage (BF%), fat mass (FM) and fat-free mass (FFM) in a cohort of male and female subjects displaying a wide range of ages and BMI levels.

Ninety-five subjects (30 ± 15 years, 170 ± 8·0 cm, 72·6 ± 14·8 kg) participated in the study. Body composition measures were taken from BIS_STA , BIS_SUP and DXA during a single visit to the laboratory following an 8- to 12-h fast in a euhydration state.

Supine BIS device and BIS_STA produced r-values >0·91 and low SEE values for all measurements compared to DXA. Effect sizes were 'trivial' for FFM comparing both BIS_SUP and BIS_STA to DXA (<0·1) and 'small' for FM and BF% (<0·39). Compared to DXA, BIS_STA resulted in lower total (TE) and constant errors/mean differences (CE) (TE < 3·6 kg, CE < -1·82 kg) versus BIS_SUP (TE < 4·35 kg, CE < -3·10 kg) for FFM.

Fat-free mass values for BIS_STA resulted in the most comparable measurements to DXA with no mean differences and the lowest total error and effect size. However, the findings indicated both BIS devices may be acceptable alternatives to DXA for BF%, FM and FFM in clinical practice.