title: Estimation of total body water from bioelectrical impedance analysis in patients with pancreatic cancer -- agreement between three methods of prediction.
abstract: BACKGROUND
  Bioelectrical impedance analysis (BIA) is a useful field measure to estimate total body water (TBW). No prediction formulae have been developed or validated against a reference method in patients with pancreatic cancer. The aim of this study was to assess the agreement between three prediction equations for the estimation of TBW in cachectic patients with pancreatic cancer.
  
  
  METHODS
  Resistance was measured at frequencies of 50 and 200 kHz in 18 outpatients (10 males and eight females, age 70.2 +/- 11.8 years) with pancreatic cancer from two tertiary Australian hospitals. Three published prediction formulae were used to calculate TBW - TBWs developed in surgical patients, TBWca-uw and TBWca-nw developed in underweight and normal weight patients with end-stage cancer.
  
  
  RESULTS
  There was no significant difference in the TBW estimated by the three prediction equations - TBWs 32.9 +/- 8.3 L, TBWca-nw 36.3 +/- 7.4 L, TBWca-uw 34.6 +/- 7.6 L. At a population level, there is agreement between prediction of TBW in patients with pancreatic cancer estimated from the three equations. The best combination of low bias and narrow limits of agreement was observed when TBW was estimated from the equation developed in the underweight cancer patients relative to the normal weight cancer patients. When no established BIA prediction equation exists, practitioners should utilize an equation developed in a population with similar critical characteristics such as diagnosis, weight loss, body mass index and/or age.
  
  
  CONCLUSIONS
  Further research is required to determine the accuracy of the BIA prediction technique against a reference method in patients with pancreatic cancer.
authors.affiliation: The Wesley Research Institute, Queensland, Australia. judithba@wesley.com.au
authors.forename: J
authors.initials: J
authors.lastname: Bauer
authors.forename: S
authors.initials: S
authors.lastname: Capra
authors.forename: P S W
authors.initials: PS
authors.lastname: Davies
authors.forename: S
authors.initials: S
authors.lastname: Ash
authors.forename: W
authors.initials: W
authors.lastname: Davidson
mesh_terms: D000368:Aged; D001823:Body Composition / Q000502:physiology*; D001834:Body Water; D002100:Cachexia / Q000378:metabolism; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015431:Weight Loss