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

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Abstract

BACKGROUND/OBJECTIVE:

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.

SUBJECTS/METHODS:

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.

RESULTS:

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).

CONCLUSIONS:

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.

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