title: Analysis, evaluation and adaptation of the ReTransQoL: a specific quality of life questionnaire for renal transplant recipients.
abstract: BACKGROUND
  End stage renal disease (ESRD) profoundly impacts the lives of patients. Kidney transplantation provides the greatest health-related quality of life (HRQOL) improvement. Its measurement has become an important outcome parameter and a very important criterion in the evaluation of any type of medical treatment, especially in the field of renal transplantation.In 2007, a specific self-administered questionnaire for renal transplant recipients was developed in the French language: the ReTransQol (RTQ).After 5 years of use, the properties of the RTQ needed to be re-evaluated in a larger sample.This paper describes the analysis of the ReTransQol and its adaptation to achieve an improved and revised version.
  
  
  METHODS
  The study design included three analysis phases for two samples of adult renal transplant recipients which came from two cross-sectional multicenter studies carried out in France in 2007 and 2012. Psychometrics properties like construct validity, acceptability and feasibility, reliability and convergent validity were evaluated and every analysis resulted in a new version of the questionnaire: the RTQ V2. The construct validity of the new RTQ was assessed with a Confirmatory Factor Analysis on a large sample of patients.
  
  
  RESULTS
  The study samples included 1,059 patients and 1,591 patients, respectively. After a principal component analysis, item reduction was performed and a total of 13 items were deleted. A final version of the RTQ V2 was created and comprised of 32 items describing 5 domains: Physical Health, Social Functioning, Medical Care, Treatment and Fear of Losing Graft.The explained variance between the first and second RTQ versions improved from 46.3% to 53.1%. All psychometric properties of RTQ V2 were satisfactory: IIC >0.4, IDV (%) of 100% and Cronbach's Alpha >0.7 in every dimension. The confirmatory analysis showed that the overall scalability of the RTQ V2 was satisfactory; all items showed a good fit to the Rasch model within each dimension, and showed INFIT statistics inside the acceptable range.
  
  
  CONCLUSIONS
  Psychometric properties allow this new version of the questionnaire to be used to assess different specific dimensions for the renal transplant population, more effectively than previously possible.
authors.affiliation: Faculté de Médecine, Laboratoire de Santé Publique, Université Aix-Marseille, Marseille EA 3279, France. davy.beauger@ap-hm.fr.
authors.forename: Davy
authors.initials: D
authors.lastname: Beauger
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Gentile
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Jouve
authors.forename: Bertrand
authors.initials: B
authors.lastname: Dussol
authors.forename: Christian
authors.initials: C
authors.lastname: Jacquelinet
authors.forename: Serge
authors.initials: S
authors.lastname: Briançon
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005163:Factor Analysis, Statistical; D005260:Female; D005602:France; D006304:Health Status; D006801:Humans; D016030:Kidney Transplantation / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D015337:Multicenter Studies as Topic; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires / Q000592:standards*