title: Body mass index and childhood obesity classification systems: A comparison of the French, International Obesity Task Force (IOTF) and World Health Organization (WHO) references.
abstract: OBJECTIVE
  This study aims to compare three body mass index (BMI)-based classification systems of childhood obesity: the French, the International Obesity Task Force (IOTF) and the World Health Organization (WHO) references.
  
  
  METHODS
  The study involved 1382 schoolchildren, recruited from the Lille Academic District in France in May 2009 aged 8.4±1.7 years (4.0-12.0 years). Their mean height and body mass were 131.5±10.9cm and 30.7±9.2kg, respectively, resulting in a BMI of 17.4±3.2kg/m(2). The weight status was defined according to the three systems considered in this study. The agreement between these references was tested using the Cohen's kappa coefficient.
  
  
  RESULTS
  The prevalence of overweight was higher with the WHO references (20.0%) in comparison with the French references (13.8%; P<0.0001) and the IOTF (16.2%; P≤0.01). A similar result was found with obesity (WHO: 11.6% vs. IOTF: 6.7%; or French references: 6.7%; P<0.0001). Agreement between the three references ranged from "moderate" to "perfect" (0.43≤κ≤1.00; P<0.0001). Kappa coefficients were higher when the three references were used to classify children as obese (0.63≤κ≤1.00; P<0.0001) as compared to classification in the overweight (obesity excluded) category (0.43≤κ≤0.94; P<0.0001). When sex and age categories (4-6 years vs. 7-12 years) were considered to define the overweight status, the lowest kappa coefficient was found between the French and WHO references in boys aged 7-12 years (κ=0.28; P<0.0001), and the highest one in girls aged 7-12 years between the French references and IOTF (κ=0.97; P<0.0001). As for obesity, agreement between the three references ranged from 0.60 to 1.00 (P<0.0001), with the lowest values obtained in the comparison of the WHO references against French references or IOTF among boys aged 7-12 years (κ=0.60; P<0.0001).
  
  
  CONCLUSIONS
  Overall, the WHO references yield an overestimation in overweight and/or obesity within this sample of schoolchildren as compared to the French references and the IOTF. The magnitude of agreement coefficients between the three references depends on of both sex and age categories. The French references seem to be in rather close agreement with the IOTF in defining overweight, especially in 7-12-year-old children.
authors.affiliation: UFR ingénierie et management de la santé, université de Lille, Loos 59120, France; Luxembourg Institute of Health (LIH), CIEC, Strassen, Luxembourg.
authors.forename: L M
authors.initials: LM
authors.lastname: Kêkê
authors.affiliation: Luxembourg Institute of Health (LIH), Population Health Department, 1445 Strassen, Luxembourg.
authors.forename: H
authors.initials: H
authors.lastname: Samouda
authors.affiliation: Luxembourg Institute of Health (LIH), Population Health Department, 1445 Strassen, Luxembourg.
authors.forename: J
authors.initials: J
authors.lastname: Jacobs
authors.affiliation: UFR ingénierie et management de la santé, université de Lille, Loos 59120, France; EA 2694, santé publique : épidémiologie et qualité des soins, université de Lille, 59000 Lille, France; Service de santé publique, agglomération de Maubeuge-Val-de-Sambre, 59600 Maubeuge, France.
authors.forename: C
authors.initials: C
authors.lastname: di Pompeo
authors.affiliation: EA 2694, santé publique : épidémiologie et qualité des soins, université de Lille, 59000 Lille, France; Département de biomathématiques, faculté des sciences biologiques et pharmaceutiques, université Lille, Lille, France.
authors.forename: M
authors.initials: M
authors.lastname: Lemdani
authors.affiliation: UFR ingénierie et management de la santé, université de Lille, Loos 59120, France; EA 2694, santé publique : épidémiologie et qualité des soins, université de Lille, 59000 Lille, France.
authors.forename: H
authors.initials: H
authors.lastname: Hubert
authors.affiliation: EA 2694, santé publique : épidémiologie et qualité des soins, université de Lille, 59000 Lille, France; Département de biomathématiques, faculté des sciences biologiques et pharmaceutiques, université Lille, Lille, France.
authors.forename: D
authors.initials: D
authors.lastname: Zitouni
authors.affiliation: UFR ingénierie et management de la santé, université de Lille, Loos 59120, France; EA 2694, santé publique : épidémiologie et qualité des soins, université de Lille, 59000 Lille, France. Electronic address: benjamin.guinhouya@univ-lille2.fr.
authors.forename: B C
authors.initials: BC
authors.lastname: Guinhouya
mesh_terms: D026683:Advisory Committees; D015992:Body Mass Index; D002648:Child; D005260:Female; D005602:France; D006801:Humans; D008297:Male; D050177:Overweight / Q000175:diagnosis; D063766:Pediatric Obesity / Q000145:classification* / Q000175:diagnosis; D012016:Reference Values; D014944:World Health Organization
keywords: Childhood obesity; Classification systems; Enfants; French references; IOTF; OMS; Obésité; Systèmes de classification; WHO