title: Longitudinal validity and responsiveness of the Food Allergy Quality of Life Questionnaire - Parent Form in children 0-12 years following positive and negative food challenges.
abstract: BACKGROUND
  There are no published studies of longitudinal health-related quality of life (HRQL) assessments of food-allergic children using a disease-specific measure.
  
  
  OBJECTIVE
  This study assessed the longitudinal measurement properties of the Food Allergy Quality of Life Questionnaire - Parent Form (FAQLQ-PF) in a sample of children undergoing food challenge.
  
  
  METHODS
  Parents of children 0-12 years completed the FAQLQ-PF and the Food Allergy Independent Measure (FAIM) pre-challenge and at 2 and 6 months post food challenge. In order to evaluate longitudinal validity, differences between Group A (positive challenge) and Group B (negative challenge) were expected over time. We computed correlation coefficients between change scores in the FAQLQ-PF and change scores in the FAIM. To determine the minimally important difference (MID), we used distributional criterion and effect size approaches. A logistic regression model profiled those children falling below this point.
  
  
  RESULTS
  Eighty-two children underwent a challenge (42 positive; 40 negative). Domains and total score improved significantly at pos-challenge time-points for both groups (all P<0.05). Sensitivity was demonstrated by significant differences between positive and negative groups at 6 months [F(2, 59)=6.221, P<0.003] and by differing improvement on relevant subscales (P<0.05). MID was 0.45 on a seven-point response scale. Poorer quality of life at baseline increased the odds by over 2.0 of no improvement in HRQL scores 6-month time-point. General maternal health (OR 1.252), number of foods avoided (OR 1.369) and children >9 years (OR 1.173) were also predictors. The model correctly identified 84% of cases below MID.
  
  
  CONCLUSIONS
  The FAQLQ-PF is sensitive to change, and has excellent longitudinal reliability and validity in a food-allergic patient population. The standard error of measurement value of 0.5 points as a threshold for meaningful change in HRQL questionnaires was confirmed. The FAQLQ-PF may be used to identify problems in children, to assess the effectiveness of clinical trials or interventions, and to guide the development of regulatory policies.
authors.affiliation: Department of Paediatrics and Child Health, Clinical Investigation Unit, Cork University Hospital, University College, Cork, Ireland. a.dunngalvin@ucc.ie
authors.forename: A
authors.initials: A
authors.lastname: DunnGalvin
authors.forename: C
authors.initials: C
authors.lastname: Cullinane
authors.forename: D A
authors.initials: DA
authors.lastname: Daly
authors.forename: B M J
authors.initials: BM
authors.lastname: Flokstra-de Blok
authors.forename: A E J
authors.initials: AE
authors.lastname: Dubois
authors.forename: J O'B
authors.initials: JO
authors.lastname: Hourihane
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D005512:Food Hypersensitivity / Q000150:complications / Q000175:diagnosis* / Q000523:psychology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D010290:Parents; D011788:Quality of Life; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires