title: Body mass index cutoff point estimation as obesity diagnostic criteria in Down syndrome adolescents.
abstract: BACKGROUND
  Adolescents with Down syndrome (DS) show high rate of overweight and tend to accumulate high amount of fat compared to the same people without the syndrome.
  
  
  OBJECTIVE
  To estimate the cutoff point of the Body Mass Index (BMI) for the diagnosis of obesity in adolescents with DS according to different references for BMI in relation to the percentage of body fat (%BF) measured by dual-energy X-ray absorptiometry (DXA).
  
  
  METHODS
  The sample was composed of 34 adolescents with DS (aged: 10 to 17 years old). BMI was evaluated according to the references of the International Obesity Task Force (IOTF), the World Health Organization (WHO) for the general population, and Myrelid et al. and Styles et al. for people with DS. The %BF was assessed by whole body DXA and classified according to National Health And Nutrition Examination Survey (NHANES, 2011).
  
  
  RESULTS
  The boys were significantly taller than the girls and this %BF higher than boys. All references who have used BMI to assess obesity was positively associated with %BF measured by DXA in the diagnosis of obesity. Using the ROC curve in relation to %BF by DXA, all references showed high sensitivity, but the z-score of BMI by WHO showed better specificity, with the value of the accuracy of 0.82 for the cutoff point above 2.14.
  
  
  CONCLUSIONS
  All the references used for the diagnosis of obesity were associated with %BF measured by DXA, and the cutoff point of z-scores above 2.14 by WHO showed better specificity.
authors.affiliation: Laboratory of Growth and Development. Center for Investigation in Pediatrics (CIPED).. juansamur@gmail.com.
authors.forename: Juan Eduardo
authors.initials: JE
authors.lastname: Samur San-Matín
authors.forename: Ezequiel Moreira
authors.initials: EM
authors.lastname: Gonçalves
authors.forename: Fabio
authors.initials: F
authors.lastname: Bertapelli
authors.forename: Roberto Teixeira
authors.initials: RT
authors.lastname: Mendes
authors.forename: Gil
authors.initials: G
authors.lastname: Guerra-Júnior
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D001823:Body Composition; D015992:Body Mass Index; D002648:Child; D004314:Down Syndrome / Q000150:complications* / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000175:diagnosis* / Q000453:epidemiology; D012015:Reference Standards; D012737:Sex Factors
keywords: Down syndrome.  Body mass index.  ROC curve. DXA.  Anthropometry.