title: A model of prediction and cross-validation of fat-free mass in men with motor complete spinal cord injury.
abstract: OBJECTIVE
  To establish and validate prediction equations by using body weight to predict legs, trunk, and whole-body fat-free mass (FFM) in men with chronic complete spinal cord injury (SCI).
  
  
  METHODS
  Cross-sectional design.
  
  
  METHODS
  Research setting in a large medical center.
  
  
  METHODS
  Individuals with SCI (N=63) divided into prediction (n=42) and cross-validation (n=21) groups.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Whole-body FFM and regional FFM were determined by using dual-energy x-ray absorptiometry. Body weight was measured by using a wheelchair weighing scale after subtracting the weight of the chair.
  
  
  RESULTS
  Body weight predicted legs FFM (legs FFM=.09×body weight+6.1; R(2)=.25, standard error of the estimate [SEE]=3.1kg, P<.01), trunk FFM (trunk FFM=.21×body weight+8.6; R(2)=.56, SEE=3.6kg, P<.0001), and whole-body FFM (whole-body FFM=.288×body weight+26.3; R(2)=.53, SEE=5.3kg, P<.0001). The whole-body FFM(predicted) (FFM predicted from the derived equations) shared 86% of the variance in whole-body FFM(measured) (FFM measured using dual-energy x-ray absorptiometry scan) (R(2)=.86, SEE=1.8kg, P<.0001), 69% of trunk FFM(measured), and 66% of legs FFM(measured). The trunk FFM(predicted) shared 69% of the variance in trunk FFM(measured) (R(2)=.69, SEE=2.7kg, P<.0001), and legs FFM(predicted) shared 67% of the variance in legs FFM(measured) (R(2)=.67, SEE=2.8kg, P<.0001). Values of FFM did not differ between the prediction and validation groups.
  
  
  CONCLUSIONS
  Body weight can be used to predict whole-body FFM and regional FFM. The predicted whole-body FFM improved the prediction of trunk FFM and legs FFM.
authors.affiliation: Spinal Cord Injury and Disorders Service, Hunter Holmes McGuire VAMC, Richmond, VA 23249, USA. ashraf.gorgey@va.gov
authors.forename: Ashraf S
authors.initials: AS
authors.lastname: Gorgey
authors.forename: David R
authors.initials: DR
authors.lastname: Dolbow
authors.forename: David R
authors.initials: DR
authors.lastname: Gater
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000502:physiology*; D000328:Adult; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D018450:Disease Progression; D006801:Humans; D015601:Injury Severity Score; D007866:Leg; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011782:Quadriplegia / Q000175:diagnosis* / Q000534:rehabilitation; D018570:Risk Assessment; D013119:Spinal Cord Injuries / Q000175:diagnosis* / Q000534:rehabilitation; D013909:Thorax