title: Cross-cultural equivalence of the patient- and parent-reported quality of life in short stature youth (QoLISSY) questionnaire.
abstract: BACKGROUND
  Testing cross-cultural equivalence of patient-reported outcomes requires sufficiently large samples per country, which is difficult to achieve in rare endocrine paediatric conditions. We describe a novel approach to cross-cultural testing of the Quality of Life in Short Stature Youth (QoLISSY) questionnaire in five countries by sequentially taking one country out (TOCO) from the total sample and iteratively comparing the resulting psychometric performance.
  
  
  METHODS
  Development of the QoLISSY proceeded from focus group discussions through pilot testing to field testing in 268 short-statured patients and their parents. To explore cross-cultural equivalence, the iterative TOCO technique was used to examine and compare the validity, reliability, and convergence of patient and parent responses on QoLISSY in the field test dataset, and to predict QoLISSY scores from clinical, socio-demographic and psychosocial variables.
  
  
  RESULTS
  Validity and reliability indicators were satisfactory for each sample after iteratively omitting one country. Comparisons with the total sample revealed cross-cultural equivalence in internal consistency and construct validity for patients and parents, high inter-rater agreement and a substantial proportion of QoLISSY variance explained by predictors.
  
  
  CONCLUSIONS
  The TOCO technique is a powerful method to overcome problems of country-specific testing of patient-reported outcome instruments. It provides an empirical support to QoLISSY's cross-cultural equivalence and is recommended for future research.
authors.affiliation: Department of Medical Psychology, University Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Bullinger
authors.forename: Julia
authors.initials: J
authors.lastname: Quitmann
authors.forename: Neuza
authors.initials: N
authors.lastname: Silva
authors.forename: Anja
authors.initials: A
authors.lastname: Rohenkohl
authors.forename: John E
authors.initials: JE
authors.lastname: Chaplin
authors.forename: Kendra
authors.initials: K
authors.lastname: DeBusk
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Mimoun
authors.forename: Eva
authors.initials: E
authors.lastname: Feigerlova
authors.forename: Michael
authors.initials: M
authors.lastname: Herdman
authors.forename: Dolores
authors.initials: D
authors.lastname: Sanz
authors.forename: Hartmut
authors.initials: H
authors.lastname: Wollmann
authors.forename: Andreas
authors.initials: A
authors.lastname: Pleil
authors.forename: Michael
authors.initials: M
authors.lastname: Power
mesh_terms: D000293:Adolescent; D002648:Child; D003431:Cross-Cultural Comparison; D005060:Europe; D005260:Female; D006130:Growth Disorders / Q000208:ethnology / Q000523:psychology*; D006801:Humans; D008297:Male; D010865:Pilot Projects; D011788:Quality of Life / Q000523:psychology*; D057566:Self Report; D011795:Surveys and Questionnaires