title: Body composition in children and adults by air displacement plethysmography.
abstract: OBJECTIVE
  Air displacement plethysmography (ADP) may provide a partial alternative to body density (Bd) and therefore body composition measurement compared to conventional hydrodensitometry (Hd) in children. As there are no evaluation studies of ADP in children, this study had a two-fold objective: to compare Bd estimates by ADP and Hd; and to compare fat estimates by both ADP and Hd to fat estimates by another reference method, dual energy X-ray absorptiometry (DXA).
  
  
  METHODS
  Obesity Research Center, St. Luke's/Roosevelt Hospital, New York, USA.
  
  
  METHODS
  One hundred and twenty subjects (66 females/54 males) who ranged in age from 6-86 y and in body mass index (BMI, kg/m2) from 14.1-40.0 kg/m2 met study entry criteria.
  
  
  METHODS
  Cross-sectional study of healthy children (age < or = 19 y) and adult group for comparison to earlier studies. Each subject completed ADP, Hd, and DXA studies on the same day. Only subjects with subjectively-judged successful Hd studies were entered into the study cohort.
  
  
  RESULTS
  There was a high correlation between Bd by ADP and Hd (Bd Hd = 0.11 + 0.896 x Bd ADP; r = 0.93, SEE = 0.008 g/cm3, P < 0.0001), although the regression line slope and intercept differed significantly from 1 and 0, respectively. Additional analyses localized a small-magnitude Bd bias in the child (n = 48) subgroup. Both ADP and Hd %fat estimates were highly correlated (r > 0.9, P < 0.0001) with %fat by DXA in child and adult subgroups. Bland-Altman analyses revealed no significant %fat bias by either ADP or Hd vs DXA in either children or adults, although a bias trend (P = 0.11) was detected in the child subgroup.
  
  
  CONCLUSIONS
  With additional refinements, the air displacement plethysmography system has the potential of providing an accurate and practical method of quantifying body fat in children as it now does in adults.
authors.affiliation: Department of Medicine, Obesity Research Center, St. Luke's/Roosevelt Hospital, Columbia University, College of Physicians and Surgeons, New York, NY 10025, USA.
authors.forename: C
authors.initials: C
authors.lastname: Nuñez
authors.forename: A J
authors.initials: AJ
authors.lastname: Kovera
authors.forename: A
authors.initials: A
authors.lastname: Pietrobelli
authors.forename: S
authors.initials: S
authors.lastname: Heshka
authors.forename: M
authors.initials: M
authors.lastname: Horlick
authors.forename: J J
authors.initials: JJ
authors.lastname: Kehayias
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: S B
authors.initials: SB
authors.lastname: Heymsfield
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000388:Air; D001823:Body Composition; D002648:Child; D005260:Female; D006801:Humans; D007101:Immersion; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010991:Plethysmography; D014867:Water
chemical_list: D014867:Water