title: Accuracy of body mass index for age to diagnose obesity in Mexican schoolchildren.
abstract: OBJECTIVE
  To compare the accuracy of three BMI-forage references (World Health Organization reference, WHO; the updated International Obesity Task Force reference, IOTF; and Centers for Disease Control and Prevention (CDC) growth charts) to diagnose obesity in Mexican children.
  
  
  METHODS
  A convenience sample of Mexican schoolchildren (n = 218) was assessed. The gold standard was the percentage of body fat estimated by deuterium dilution technique. Sensitivity and specificity of the classical cutoff point of BMI-for-age to identify obesity (i.e. > 2.00 standard deviation, SD) were estimated. The accuracy (i.e. area under the curve, AUC) of three BMI-for-age references for the diagnosis of obesity was estimated with the receiver operating characteristic (ROC) curves method. The optimal cutoff point (OCP) was determined.
  
  
  RESULTS
  The cutoff points to identify obesity had low (WHO reference: 57.6%, CDC: 53.5%) to very low (IOTF reference: 40.4%) sensitivities, but adequate specificities (91.6%, 95.0%, and, 97.5%, respectively). The AUC of the three references were adequate (0.89). For the IOTF reference, the AUC was lower among the older children. The OCP for the CDC reference (1.24 SD) was lower than the OCP for WHO (1.53 SD) and IOTF charts (1.47 SD).
  
  
  CONCLUSIONS
  The classical cutoff point for obesity has low sensitivity--especially for the IOTF reference. The accuracy of the three references was similar. However, to obtain comparable diagnosis of obesity different cutoff points should be used depending of the reference.
authors.affiliation: Maestría y Doctorado en Ciencias Médicas, Odontológicas y de la Salud, Universidad Nacional Autónoma de México.. ampablo@live.com.
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Mendoza Pablo
authors.affiliation: Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del I.P.N.. jvaldes@cinvestav.mx.
authors.forename: Jesús
authors.initials: J
authors.lastname: Valdés
authors.affiliation: Departamento de Atención a la Salud, Universidad Autónoma Metropolitana Xochimilco, México.. lortiz@correo.xoc.uam.mx.
authors.forename: Luis
authors.initials: L
authors.lastname: Ortiz-Hernández
mesh_terms: D050154:Adiposity; D000367:Age Factors; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008800:Mexico; D009765:Obesity / Q000175:diagnosis*; D012015:Reference Standards; D015203:Reproducibility of Results