title: 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: 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.
  
  
  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.
authors: Research Team for Promoting Independence of the Elderly, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan. mijiak@tmig.or.jp
authors: M
authors: M
authors: Kim
authors: H
authors: H
authors: Kim
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000273:Adipose Tissue; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D001823:Body Composition; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D005260:Female; D016330:Frail Elderly; D006801:Humans; D016014:Linear Models; D015203:Reproducibility of Results