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

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 (R-2) for whole-body FM (R-2 = 0.94, s.e. of estimate (SEE) = 1.2 kg), whole-body LM (R-2 = 0.85, SEE = 1.4 kg), and appendicular FM (R-2 = 0.82, SEE = 1.1 kg) were observed between SMF-BIA and DXA. The R-2 coefficient for appendicular LM was moderate (R-2 = 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. European Journal of Clinical Nutrition (2013) 67, 395-400; doi:10.1038/ejcn.2013.9; published online 6 February 2013