title: Validity of the childhood health assessment questionnaire is independent of age in juvenile idiopathic arthritis.
abstract: OBJECTIVE
  To determine whether the Childhood Health Assessment Questionnaire (CHAQ) is valid for the comparison of different age subgroups and for longitudinal studies in juvenile idiopathic arthritis (JIA).
  
  
  METHODS
  A CHAQ was administered to 306 children with JIA. Rasch analyses were used to compare the difficulty of each of the 30 items of the questionnaire for children of 2 age groups (> or =10 years old and <10 years old).
  
  
  RESULTS
  Independent of the physical disability level assessed by the Rasch model, 8 of the 30 items (27%) of the CHAQ were rated significantly different in the 2 age groups. Despite this age-related variation in item difficulty, the impact on the CHAQ disability index using its original scoring system remained low (about 0.25 points on a scale of 0-3).
  
  
  CONCLUSIONS
  The difficulty of 8 of 30 items of the CHAQ depends on the respondent's age. Nevertheless, the design of the CHAQ and its scoring system remove most of the expected physical development bias.
authors.affiliation: Hôpital Louis Mourier, Colombes, France. jacques.pouchot@lmr.ap-hop-paris.fr
authors.forename: Jacques
authors.initials: J
authors.lastname: Pouchot
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Ecosse
authors.forename: Joël
authors.initials: J
authors.lastname: Coste
authors.forename: Francis
authors.initials: F
authors.lastname: Guillemin
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001171:Arthritis, Juvenile / Q000175:diagnosis* / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires / Q000592:standards*