title: Comparing measures of fat-free mass in overweight older adults using three different bioelectrical impedance devices and three prediction equations.
abstract: OBJECTIVE
  To compare measures of fat-free mass (FFM) by three different bioelectrical impedance analysis (BIA) devices and to assess the agreement between three different equations validated in older adult and/or overweight populations.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Orthopaedics ward of Brisbane public hospital, Australia.
  
  
  METHODS
  Twenty-two overweight, older Australians (72 yr ± 6.4, BMI 34 kg/m² ± 5.5) with knee osteoarthritis.
  
  
  METHODS
  Body composition was measured using three BIA devices: Tanita 300-GS (foot-to-foot), Impedimed DF50 (hand-to-foot) and Impedimed SFB7 (bioelectrical impedance spectroscopy (BIS)). Three equations for predicting FFM were selected based on their ability to be applied to an older adult and/ or overweight population. Impedance values were extracted from the hand-to-foot BIA device and included in the equations to estimate FFM.
  
  
  RESULTS
  The mean FFM measured by BIS (57.6 kg ± 9.1) differed significantly from those measured by foot-to-foot (54.6 kg ± 8.7) and hand-to-foot BIA (53.2 kg ± 10.5) (P < 0.001). The mean ± SD FFM predicted by three equations using raw data from hand-to-foot BIA were 54.7 kg ± 8.9, 54.7 kg ± 7.9 and 52.9 kg ± 11.05 respectively. These results did not differ from the FFM predicted by the hand-to-foot device (F = 2.66, P = 0.118).
  
  
  CONCLUSIONS
  Our results suggest that foot-to-foot and hand-to-foot BIA may be used interchangeably in overweight older adults at the group level but due to the large limits of agreement may lead to unacceptable error in individuals. There was no difference between the three prediction equations however these results should be confirmed within a larger sample and against a reference standard.
authors.affiliation: School of Public Health - Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland 4059, Australia. rebecca.ramsey@qut.edu.au
authors.forename: R
authors.initials: R
authors.lastname: Ramsey
authors.forename: E
authors.initials: E
authors.lastname: Isenring
authors.forename: L
authors.initials: L
authors.lastname: Daniels
mesh_terms: D000368:Aged; D001315:Australia; D001823:Body Composition / Q000502:physiology*; D001825:Body Fluid Compartments / Q000502:physiology*; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D005260:Female; D005528:Foot / Q000502:physiology; D015577:Geriatric Assessment / Q000379:methods*; D006225:Hand / Q000502:physiology; D006801:Humans; D008297:Male; D055641:Mathematical Concepts; D009765:Obesity / Q000503:physiopathology*; D020370:Osteoarthritis, Knee; D015203:Reproducibility of Results