title: Body Mass Index standards based on agreement with health-related body fat.
abstract: BACKGROUND
  Multiple screening tools, such as BMI and skinfold-derived percent body fat (%BF), are available to identify youth at risk of excess adiposity. However, poor classification agreement among these tools can be problematic for those interpreting test results.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the validity of using BMI as an estimate of %BF in youth and to identify optimal BMI thresholds for identifying at-risk children and adolescents based on %BF.
  
  
  METHODS
  Percent body fat was derived from the skinfold thicknesses of children aged 5-18 years from three cross-sectional waves of the National Health and Nutrition Examination Survey (NHANES [1999-2004]; N=8269). Stature and body mass from the same data set were used to calculate BMI. Receiver operating characteristic (ROC) analysis was employed to determine the optimal BMI thresholds for detecting previously created %BF standards.
  
  
  RESULTS
  The optimal BMI percentile associated with the low risk %BF threshold was the 83 rd and 80th in boys and girls, respectively. The selected BMI percentiles associated with the higher risk threshold were the 92 nd and 90th in boys and girls, respectively. Overall, classification accuracy when using BMI percentiles to identify the two %BF risk groups ranged from 86.9% to 89.1%.
  
  
  CONCLUSIONS
  BMI and skinfold-derived %BF demonstrate reasonable agreement when used to classify adiposity status in children and adolescents.
authors.affiliation: School of Kinesiology and Recreation, Illinois State University, Normal, Illinois 61790, USA. klaurso@ilstu.edu
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Laurson
authors.forename: Joey C
authors.initials: JC
authors.lastname: Eisenmann
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Welk
mesh_terms: D000273:Adipose Tissue; D000293:Adolescent; D000367:Age Factors; D001823:Body Composition; D001827:Body Height; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008403:Mass Screening; D009765:Obesity / Q000175:diagnosis; D012372:ROC Curve; D012015:Reference Standards; D015203:Reproducibility of Results; D012307:Risk Factors; D012737:Sex Factors; D012885:Skinfold Thickness; D014481:United States