Correction of body-mass index using body-shape perception and socioeconomic status in adolescent self-report surveys.
OBJECTIVE
To propose a simple correction of body-mass index (BMI) based on self-reported weight and height (reported BMI) using gender, body shape perception and socioeconomic status in an adolescent population.


METHODS
341 boys and girls aged 17-18 years were randomly selected from a representative sample of 2165 French adolescents living in Paris surveyed in 2010. After an anonymous self-administered pen-and-paper questionnaire asking for height, weight, body shape perception (feeling too thin, about the right weight or too fat) and socioeconomic status, subjects were measured and weighed. BMI categories were computed according to Cole's cut-offs. Reported BMIs were corrected using linear regressions and ROC analyses and checked with cross-validation and multiple imputations to handle missing values. Agreement between actual and corrected BMI values was estimated with Kappa indexes and Intraclass correlation coefficients (ICC).


RESULTS
On average, BMIs were underreported, especially among girls. Kappa indexes between actual and reported BMI were low, especially for girls: 0.56 95%CI = [0.42-0.70] for boys and 0.45 95%CI = [0.30-0.60] for girls. The regression of reported BMI by gender and body shape perception gave the most balanced results for both genders: the Kappa and ICC obtained were 0.63 95%CI = [0.50-0.76] and 0.67, 95%CI = [0.58-0.74] for boys; 0.65 95%CI = [0.52-0.78] and 0.74, 95%CI = [0.66-0.81] for girls. The regression of reported BMI by gender and socioeconomic status led to similar corrections while the ROC analyses were inaccurate.


CONCLUSIONS
Using body shape perception, or socioeconomic status and gender is a promising way of correcting BMI in self-administered questionnaires, especially for girls.
Institut national d'études démographiques (INED), Paris, France; Inserm, U669, Univ Paris-Sud and Univ Paris Descartes, UMR-S0669, Paris, France.
Stéphane
S
Legleye
Institut national de prévention et d'éducation à la santé (INPES), Saint-Denis, France; Cermes3 - Equipe Cesames (Centre de recherche Médecine, Sciences, Santé, Santé mentale, Société, Université Paris Descartes/CNRS UMR 8211/Inserm U988/EHESS), Paris, France.
François
F
Beck
French Monitoring Centre for Drugs and Drug Addiction - Observatoire Français des Drogues et des Toxicomanies (OFDT), Saint-Denis, France.
Stanislas
S
Spilka
Inserm, U669, Univ Paris-Sud and Univ Paris Descartes, UMR-S0669, Paris, France.
Nearkasen
N
Chau
D000293:Adolescent; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D010465:Perception; D057566:Self Report; D012727:Sex Characteristics; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires