title: Sensitivity and specificity of body mass index and skinfold thicknesses in detecting excess adiposity in children aged 8-12 years.
abstract: OBJECTIVE
  The study aimed to evaluate the sensitivity (SN) and specificity (SP) of body mass index (BMI) and skinfold thicknesses in detecting excess adiposity in children.
  
  
  METHODS
  Cross-sectional.
  
  
  METHODS
  986 children (500 females and 486 males) aged 10 +/- 1 years (mean +/- SD; range: 8-12 years) were studied. All underwent anthropometric measurements and bioelectrical impedance analysis (BIA). Dual-energy X-ray absorptiometry (DXA) was performed in 52 children to develop a population-specific algorithm for the assessment of fat-free mass (FFM) from BIA. The algorithm was applied to the remaining 934 children to estimate their FFM. Fat mass (FM) was obtained by subtracting FFM from weight (Wt). Values of FM:Wt were transformed in Z-scores and converted into 19 percentile categories (from 5 to 95 in steps of 5). The same procedure was performed with BMI and the log-transformed sum of four skinfold thicknesses (triceps, biceps, subscapular and suprailiac; lt-4SF). Excess adiposity was defined as a level of FM:Wt greater than the internally derived 85th percentile. SN and SP of each internally derived percentile of BMI and lt-4SF in detecting excess adiposity were calculated.
  
  
  RESULTS
  In the pooled sample (n = 934), SN and SP were 0.39 and 0.99 for the 95th percentile of BMI, 0.65 and 0.95 for the 85th percentile of BMI, and 0.75 and 0.94 for the 85th percentile of lt-4SF.
  
  
  CONCLUSIONS
  BMI percentiles employed in the present study have a high SP but a low SN in detecting excess adiposity in 8-12-year-old children. The use of the sum of four skinfolds has the potential to increase the SN of a screening programme for excess adiposity in children of this age.
authors.affiliation: University of Modena and Reggio Emilia, Italy. giorgiobedogni@libero.it
authors.forename: G
authors.initials: G
authors.lastname: Bedogni
authors.forename: L
authors.initials: L
authors.lastname: Iughetti
authors.forename: M
authors.initials: M
authors.lastname: Ferrari
authors.forename: M
authors.initials: M
authors.lastname: Malavolti
authors.forename: M
authors.initials: M
authors.lastname: Poli
authors.forename: S
authors.initials: S
authors.lastname: Bernasconi
authors.forename: N
authors.initials: N
authors.lastname: Battistini
mesh_terms: D015502:Absorptiometry, Photon; D000465:Algorithms; D001823:Body Composition; D015992:Body Mass Index; D002648:Child; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000175:diagnosis*; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012737:Sex Factors; D012885:Skinfold Thickness