title: New body fat prediction equations for severely obese patients.
abstract: OBJECTIVE
  Severe obesity imposes physical limitations to body composition assessment. Our aim was to compare body fat (BF) estimations of severely obese patients obtained by bioelectrical impedance (BIA) and air displacement plethysmography (ADP) for development of new equations for BF prediction.
  
  
  METHODS
  Severely obese subjects (83 female/36 male, mean age=41.6+/-11.6 years) had BF estimated by BIA and ADP. The agreement of the data was evaluated using Bland-Altman's graphic and concordance correlation coefficient (CCC). A multivariate regression analysis was performed to develop and validate new predictive equations.
  
  
  RESULTS
  BF estimations from BIA (64.8+/-15 kg) and ADP (65.6+/-16.4 kg) did not differ (p>0.05, with good accuracy, precision, and CCC), but the Bland- Altman graphic showed a wide limit of agreement (-10.4; 8.8). The standard BIA equation overestimated BF in women (-1.3 kg) and underestimated BF in men (5.6 kg; p<0.05). Two BF new predictive equations were generated after BIA measurement, which predicted BF with higher accuracy, precision, CCC, and limits of agreement than the standard BIA equation.
  
  
  CONCLUSIONS
  Standard BIA equations were inadequate for estimating BF in severely obese patients. Equations developed especially for this population provide more accurate BF assessment.
authors.affiliation: Department of Gastroenterology, Digestive Surgery Division-LIM 35, University of São Paulo School of Medicine, São Paulo, Brazil. mikahorie@yahoo.com.br
authors.forename: Lilian Mika
authors.initials: LM
authors.lastname: Horie
authors.forename: Maria Cristina Gonzalez
authors.initials: MC
authors.lastname: Barbosa-Silva
authors.forename: Raquel Susana
authors.initials: RS
authors.lastname: Torrinhas
authors.forename: Marco Túlio
authors.initials: MT
authors.lastname: de Mello
authors.forename: Ivan
authors.initials: I
authors.lastname: Cecconello
authors.forename: Dan Linetzky
authors.initials: DL
authors.lastname: Waitzberg
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology / Q000378:metabolism; D000328:Adult; D000886:Anthropometry; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D015999:Multivariate Analysis; D009767:Obesity, Morbid / Q000145:classification* / Q000175:diagnosis; D010991:Plethysmography; D011237:Predictive Value of Tests