title: Measurement of body fat by dual-energy X-ray absorptiometry and bioimpedance analysis in men with prostate cancer.
abstract: OBJECTIVE
  The aims of this study were to determine the percentage of body fat (%BF) by dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) using a standard adult equation and BIA using a standard geriatric equation in a population of older men with prostate cancer and to compare the results from these different methods.
  
  
  METHODS
  We conducted a cross-sectional study in 38 men with locally advanced, node-positive, or recurrent prostate cancer and no history of androgen-deprivation therapy. Body composition was evaluated by DXA with the use of a Hologic 4500A densitometer and BIA. BIA %BF was calculated by using standard equations developed for adult and geriatric populations.
  
  
  RESULTS
  %BF by DXA, BIA with the standard adult equation, BIA with the standard geriatric equation, and BIA with the age-appropriate equation were 26.7 +/- 5.3%, 22.5 +/- 5.6%, 38.2 +/- 6.9%, and 35.4 +/- 9.6%, respectively. There were statistically significant differences between %BF by DXA and all BIA estimates. By using the methods described by Bland and Altman (Lancet 1986;1(8476):307), the standard adult equation showed the least bias and variability.
  
  
  CONCLUSIONS
  In this group of men with prostate cancer, BIA with the standard adult equation provided a reasonable estimate of %BF compared with DXA, although the differences were statistically significant. BIA with the standard geriatric equation, however, markedly overestimated %BF compared with DXA, even when its use was restricted to elderly men.
authors.affiliation: Division of Hematology and Oncology, Massachusetts General Hospital, 100 Blossom Street, Boston, MA 02114, USA. smith.matthew@mgh.harvard.edu
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Smith
authors.forename: Vanessa
authors.initials: V
authors.lastname: Fuchs
authors.forename: Ellen J
authors.initials: EJ
authors.lastname: Anderson
authors.forename: Mary Anne
authors.initials: MA
authors.lastname: Fallon
authors.forename: Judith
authors.initials: J
authors.lastname: Manola
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue; D000368:Aged; D001823:Body Composition; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011471:Prostatic Neoplasms / Q000503:physiopathology*