title: Development and psychometric validation of measures to assess the impact of phenylketonuria and its dietary treatment on patients' and parents' quality of life: the phenylketonuria - quality of life (PKU-QOL) questionnaires.
abstract: BACKGROUND
  The aim of our study was to develop and validate the first set of PKU-specific Health-related Quality of Life (HRQoL) questionnaires that: 1) were developed for patients with PKU and their parents, 2) cover the physical, emotional, and social impacts of PKU and its treatment on patients' lives, 3) are age specific (Child PKU-QOL, Adolescent PKU-QOL, Adult PKU-QOL), 4) enable the evaluation of the HRQoL of children by their parents (Parent PKU-QOL), and 5) have been cross-culturally adapted for use in seven countries (i.e. France, Germany, Italy, The Netherlands, Spain, Turkey and the UK).
  
  
  METHODS
  The PKU-QOL questionnaires were developed according to reference methods including patients', parents' and healthcare professionals' interviews; testing in a pilot study (qualitative step in six countries), and linguistic validation of the finalised pilot versions in Turkish. For finalisation and psychometric validation, the pilot versions were included in a multicentre, prospective, non-interventional, observational study conducted in 34 sites in France, Germany, Italy, The Netherlands, Spain, Turkey and the UK. Iterative multi-trait analyses were conducted. Psychometric properties were assessed (concurrent and clinical validity, internal consistency reliability and test-retest reliability).
  
  
  RESULTS
  Data from 559 subjects (306 patients, 253 parents) were analysed. After finalisation, the PKU-QOL questionnaires included 40 items (Child PKU-QOL), 58 items (Adolescent PKU-QOL), 65 items (Adult PKU-QOL) and 54 items (Parent PKU-QOL), distributed in four modules: PKU symptoms, PKU in general, administration of Phe-free protein supplements and dietary protein restriction. The measurement properties of the Adolescent, Adult and Parent PKU-QOL questionnaires were overall fairly satisfactory, but weaker for the Child questionnaire.
  
  
  CONCLUSIONS
  The four PKU-QOL questionnaires developed for different ages (Child PKU-QOL, Adolescent PKU-QOL, Adult PKU-QOL), and for parents of children with PKU (Parent PKU-QOL) are valid and reliable instruments for assessing the multifaceted impact of PKU on patients of different age groups (children, adolescents and adults) and their parents, and are available for use in seven countries. They are very promising tools to explore how patients' perceptions evolve with age, to increase knowledge of the impact of PKU on patients and parents in different countries, and to help monitor the effect of therapeutic strategies.
authors.affiliation: Mapi, Health Economics & Outcomes Research and Strategic Market Access, 27 rue de la Villette, Lyon, France. aregnault@mapigroup.com.
authors.forename: Antoine
authors.initials: A
authors.lastname: Regnault
authors.affiliation: Division of Metabolic Diseases, Department of Paediatrics, University Hospital of Padova, Padova, Italy. alberto.burlina@unipd.it.
authors.forename: Alberto
authors.initials: A
authors.lastname: Burlina
authors.affiliation: Hayward Genetics Center, Tulane University School of Medicine, New Orleans, Louisiana, USA. acunnin@tulane.edu.
authors.forename: Amy
authors.initials: A
authors.lastname: Cunningham
authors.affiliation: Infection Control Program, University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland. Esther.Bettiol@hcuge.ch.
authors.forename: Esther
authors.initials: E
authors.lastname: Bettiol
authors.affiliation: EMD Serono Inc, Billerica, Massachusetts, USA. flavie.moreau-stucker@emdserono.com.
authors.forename: Flavie
authors.initials: F
authors.lastname: Moreau-Stucker
authors.affiliation: Mapi, Health Economics & Outcomes Research and Strategic Market Access, 27 rue de la Villette, Lyon, France. KBenmedjahed@mapigroup.com.
authors.forename: Khadra
authors.initials: K
authors.lastname: Benmedjahed
authors.affiliation: Department of Pediatrics, Division of Metabolic Disorders, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands. a.m.bosch@amc.uva.nl.
authors.forename: Annet M
authors.initials: AM
authors.lastname: Bosch
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D010661:Phenylketonurias / Q000378:metabolism / Q000503:physiopathology* / Q000523:psychology*; D011446:Prospective Studies; D011594:Psychometrics / Q000379:methods*; D011788:Quality of Life; D011795:Surveys and Questionnaires; D055815:Young Adult