Comment on ‘Accuracy of segmental multi-frequency bioelectrical impedance analysis for assessing whole-body and appendicular fat mass and lean soft tissue mass in frail women aged 75 years and older’

Abstract

We aimed to examine the accuracy of segmental multi-frequency bioelectrical impedance analysis (SMF-BIA) for the assessment of whole-body and appendicular fat mass (FM) and lean soft tissue mass (LM) in frail older women, using dual-energy X-ray absorptiometry (DXA) as a reference method. All 129 community-dwelling Japanese frail older women with a mean age of 80.9 years (range, 75–89 years) from the Frailty Intervention Trial were recruited. The agreements between SMF-BIA and DXA for whole-body and appendicular body composition were assessed using simple linear regression and Bland–Altman analysis. High coefficients of determination (R2) for whole-body FM (R2=0.94, s.e. of estimate (SEE)=1.2 kg), whole-body LM (R2=0.85, SEE=1.4 kg), and appendicular FM (R2=0.82, SEE=1.1 kg) were observed between SMF-BIA and DXA. The R2 coefficient for appendicular LM was moderate (R2=0.76, SEE=0.8 kg). Bland–Altman plots demonstrated that there was systematic (constant) bias (that is, DXA minus SMF-BIA) with overestimation of whole-body FM (bias=−1.2 kg, 95% confidence interval (CI)=−1.5 to −0.1) and underestimation of whole-body LM (bias=2.1 kg, 95% CI=1.8–2.3) by SMF-BIA. Similar, the appendicular measurements also demonstrated systematic bias with overestimation of appendicular FM (bias=−0.3 kg, 95% CI=−0.5 to −0.1) and underestimation of whole-body LM (bias=1.5 kg, 95% CI=1.4–1.7) by SMF-BIA. In addition, the individual level accuracy demonstrated a non-proportional bias for whole-body LM (r=0.08, P=0.338) and appendicular FM (r=0.07, P=0.413). SMF-BIA had acceptable accuracy for the estimation of whole-body and appendicular FM and LM in frail older women, although SMF-BIA underestimated LM and overestimated FM relative to DXA.