title: Ethnic variability in body size, proportions and composition in children aged 5 to 11 years: is ethnic-specific calibration of bioelectrical impedance required?
abstract: BACKGROUND
  Bioelectrical Impedance Analysis (BIA) has the potential to be used widely as a method of assessing body fatness and composition, both in clinical and community settings. BIA provides bioelectrical properties, such as whole-body impedance which ideally needs to be calibrated against a gold-standard method in order to provide accurate estimates of fat-free mass. UK studies in older children and adolescents have shown that, when used in multi-ethnic populations, calibration equations need to include ethnic-specific terms, but whether this holds true for younger children remains to be elucidated. The aims of this study were to examine ethnic differences in body size, proportions and composition in children aged 5 to 11 years, and to establish the extent to which such differences could influence BIA calibration.
  
  
  METHODS
  In a multi-ethnic population of 2171 London primary school-children (47% boys; 34% White, 29% Black African/Caribbean, 25% South Asian, 12% Other) detailed anthropometric measurements were performed and ethnic differences in body size and proportion were assessed. Ethnic differences in fat-free mass, derived by deuterium dilution, were further evaluated in a subsample of the population (n = 698). Multiple linear regression models were used to calibrate BIA against deuterium dilution.
  
  
  RESULTS
  In children < 11 years of age, Black African/Caribbean children were significantly taller, heavier and had larger body size than children of other ethnicities. They also had larger waist and limb girths and relatively longer legs. Despite these differences, ethnic-specific terms did not contribute significantly to the BIA calibration equation (Fat-free mass = 1.12+0.71*(height2/impedance)+0.18*weight).
  
  
  CONCLUSIONS
  Although clear ethnic differences in body size, proportions and composition were evident in this population of young children aged 5 to 11 years, an ethnic-specific BIA calibration equation was not required.
authors.affiliation: Respiratory, Critical Care and Anaesthesia Section, UCL Institute of Child Health, London, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Lee
authors.affiliation: Respiratory, Critical Care and Anaesthesia Section, UCL Institute of Child Health, London, United Kingdom.
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Bountziouka
authors.affiliation: Respiratory, Critical Care and Anaesthesia Section, UCL Institute of Child Health, London, United Kingdom.
authors.forename: Sooky
authors.initials: S
authors.lastname: Lum
authors.affiliation: Respiratory, Critical Care and Anaesthesia Section, UCL Institute of Child Health, London, United Kingdom.
authors.forename: Janet
authors.initials: J
authors.lastname: Stocks
authors.affiliation: Respiratory, Critical Care and Anaesthesia Section, UCL Institute of Child Health, London, United Kingdom.
authors.forename: Rachel
authors.initials: R
authors.lastname: Bonner
authors.affiliation: Postgraduate medical education, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom.
authors.forename: Mitesh
authors.initials: M
authors.lastname: Naik
authors.affiliation: General Practice Vocational Training Scheme, North Devon District Hospital, Barnstaple, United Kingdom.
authors.forename: Helen
authors.initials: H
authors.lastname: Fothergill
authors.affiliation: Childhood Nutrition Research Centre, UCL Institute of Child Health, London, United Kingdom.
authors.forename: Jonathan C K
authors.initials: JC
authors.lastname: Wells
mesh_terms: D000273:Adipose Tissue; D000886:Anthropometry; D001823:Body Composition / Q000235:genetics*; D049628:Body Size / Q000235:genetics*; D001835:Body Weight / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D017097:Electric Impedance; D005006:Ethnicity / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008962:Models, Theoretical