title: Self-reporting and measurement of body mass index in adolescents: refusals and validity, and the possible role of socioeconomic and health-related factors.
abstract: BACKGROUND
  Body mass index assessment using self-reported height and weight (BMIsr) can encounter refusals and under/over-reporting while for assessment with measured data (BMIm) refusals can be more frequent. This could relate to socioeconomic and health-related factors. We explored these issues by investigating numerous potential factors: gender, age, family structure, father's occupation, income, physical/sports activity, subjective weight perception, school performance, unhealthy behaviours, physical/psychological health, social relationships, living environment, having sustained violence, sexual abuse, and involvement in violence.
  
  
  METHODS
  The sample included 1559 adolescents from middle schools in north-eastern France. They completed a questionnaire including socioeconomic and health-related data, self-reported height/weight, measured height/weight, and weight perception (participation rate 94%). Data were analysed using logistic regression models.
  
  
  RESULTS
  BMIsr encountered under-reporting (with change in BMI category, 11.8%), over-reporting (6.0%), and reporting refusals (3.6%). BMIm encountered more numerous refusals (7.9%). Reporting refusal was related to living with a single parent, low school performance, lack of physical/sports activity, sustained violence, poor psychological health, and poor social relationships (gender/age-adjusted odds ratios 1.95 to 2.91). Further to these factors, measurement refusal was related to older age, having divorced/separated parents, a father being a manual worker/inactive, insufficient family income, tobacco/cannabis use, involvement in violence, poor physical health, and poor living environment (1.30 to 3.68). Under-reporting was related to male gender, involvement in violence, poor psychological health, and overweight/obesity (as assessed with BMIm) (1.52 to 11). Over-reporting was related to male gender, younger age, alcohol consumption, and underweight (1.30 to 5.35). Weight perception was linked to reporting refusals and under/over-reporting, but slightly linked to measurement refusal. The contributions of socioeconomic and health-related factors to the associations of weight perception with reporting refusal and under/over-reporting ranged from -82% to 44%. There were substantial discrepancies in the associations between socioeconomic/health-related factors and overweight/obesity assessed with BMIsr and BMIm.
  
  
  CONCLUSIONS
  BMIsr and BMIm were affected by numerous biases related to vulnerability which were also obesity risk factors. BMIsr encountered under/over-reporting which were related to some socioeconomic and health-related factors, weight perception, and BMIm. BMIm was more affected by refusals than BMIsr due to socioeconomic and health-related factors. Further research is needed.
authors.affiliation: INSERM, U669, Paris F-75014, France. Nearkasen.Chau@wanadoo.fr.
authors.forename: Nearkasen
authors.initials: N
authors.lastname: Chau
authors.forename: Kénora
authors.initials: K
authors.lastname: Chau
authors.forename: Aurélie
authors.initials: A
authors.lastname: Mayet
authors.forename: Michèle
authors.initials: M
authors.lastname: Baumann
authors.forename: Stéphane
authors.initials: S
authors.lastname: Legleye
authors.forename: Bruno
authors.initials: B
authors.lastname: Falissard
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000886:Anthropometry; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D005602:France; D015438:Health Behavior; D006304:Health Status; D006801:Humans; D016015:Logistic Models; D008297:Male; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology*; D050177:Overweight / Q000175:diagnosis / Q000453:epidemiology; D010349:Patient Compliance / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D018570:Risk Assessment; D057566:Self Report; D012680:Sensitivity and Specificity; D012931:Social Environment; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires