title: Accuracy of bioelectrical impedance consumer devices for measurement of body composition in comparison to whole body magnetic resonance imaging and dual X-ray absorptiometry.
abstract: OBJECTIVE
  To compare body composition determined by bioelectrical impedance (BIA) consumer devices against criterion estimates determined by whole body magnetic resonance imaging (MRI) and dual energy X-ray absorptiometry (DXA) in healthy normal weight, overweight and obese adults.
  
  
  METHODS
  In 106 adults (54 females, 52 males, age 54.2 +/- 16.1 years, BMI 25.8 +/- 4.4 kg/m(2)) fat mass (FM), skeletal muscle mass (SM), total body bone-free lean mass (TBBLM), and level of visceral fat mass (VF) were estimated by 3 single-frequency bipedal (foot-to-foot) and one tretrapolar BIA device, and compared to body composition measured by MRI and DXA. Bland-Altman and simple linear regression analyses were used to determine agreement between methods.
  
  
  RESULTS
  %FMDXA, SMMRI or TBBLMDXA showed good relative and absolute agreement with two bipolar and one tetrapolar instrument (r(2) = 0.92-0.96; all p < 0.001; mean bias <1.5 %FM and <1 kg SM or TBBLM) and less relative and absolute agreement for another bipolar device (r(2) = 0.82 and 0.84, mean bias approximately 3 %FM and approximately 3 kg SM). The 95% limits of agreement (bias +/- 2 SD) were narrowest for the tetrapolar device (-6.59 to 4.61 %FM and -4.62 to 4.74 kg SM) and widest for bipolar instruments (up to -14.54 to 8.58 %FM and -9.52 to 3.92 kg SM). Systematic biases for %FM were found for all bipedal devices, but not for the tetrapolar instrument.
  
  
  CONCLUSIONS
  Because of the lower agreement between foot-to-foot BIA and DXA or MRI for the assessment of body composition in individuals, tetrapolar electrode arrangement should be preferred for individual or public use. Bipolar devices provide accurate results for field studies with group estimation.
authors.affiliation: Institut fur Humanernahrung und Lebensmittelkunde, Christian-Albrechts-Universitat, Kiel, Germany. abosyw@nutrfoodsc.uni-kiel.de
authors.forename: Anja
authors.initials: A
authors.lastname: Bosy-Westphal
authors.forename: Wiebke
authors.initials: W
authors.lastname: Later
authors.forename: Britta
authors.initials: B
authors.lastname: Hitze
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sato
authors.forename: Elke
authors.initials: E
authors.lastname: Kossel
authors.forename: Claus-Christian
authors.initials: CC
authors.lastname: Gluer
authors.forename: Martin
authors.initials: M
authors.lastname: Heller
authors.forename: Manfred James
authors.initials: MJ
authors.lastname: Muller
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D001823:Body Composition; D050218:Body Fat Distribution; D015992:Body Mass Index; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology; D012680:Sensitivity and Specificity