title: Validity of self-reported body mass index of Japanese children and adolescents.
abstract: BACKGROUND
  Self-reported body mass index (BMI) has been widely used in epidemiological studies, but no study thus far has validated the self-reported BMI of Japanese children and adolescents. The aim of the present study was to assess the accuracy of self-reported BMI and its use for classification into weight categories.
  
  
  METHODS
  Fifth- and eighth-grade students (n= 358) from all schools in Shunan City, Japan, from 2006 to 2010 were included. BMI was calculated from both self-reported and measured data. Pearson's correlation, Kappa statistics and the number of overweight children, and Bland-Altman plots with 95% limits of agreement were calculated to assess the agreement.
  
  
  RESULTS
  Pearson's correlation between self-reported and measured data ranged between 0.946 and 0.987 for height, 0.978 and 0.992 for weight, and 0.930 and 0.964 for BMI, depending on gender or age. Kappa was excellent: 0.949 for boys, 0.867 for girls, 0.897 for 10-11-year-old children, 0.928 for 13-14-year-old adolescents. The number of overweight children based on self-reported BMI was not significantly different from that based on measured BMI. The 95% limits of agreement were -3.62 and 2.90 cm for height, -2.80 and 2.38 kg for weight, and -1.42 and 1.44 kg/m(2) for BMI.
  
  
  CONCLUSIONS
  Self-reported BMI was generally reliable for predicting the number of overweight Japanese children and adolescents. There is slight discrepancy, however, between self-reported BMI and measured BMI, and self-reported BMI should be used with caution, keeping the variance and concordance rate in mind.
authors.affiliation: Department of Public Health, Yamaguchi University, Ube, Japan. yoshitac@yamaguchiu.ac.jp
authors.forename: Norikazu
authors.initials: N
authors.lastname: Yoshitake
authors.forename: Masayuki
authors.initials: M
authors.lastname: Okuda
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sasaki
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kunitsugu
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hobara
mesh_terms: D000293:Adolescent; D044466:Asian People; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D057566:Self Report