title: Cross-cultural validity of four quality of life scales in persons with spinal cord injury.
abstract: BACKGROUND
  Quality of life (QoL) in persons with spinal cord injury (SCI) has been found to differ across countries. However, comparability of measurement results between countries depends on the cross-cultural validity of the applied instruments. The study examined the metric quality and cross-cultural validity of the Satisfaction with Life Scale (SWLS), the Life Satisfaction Questionnaire (LISAT-9), the Personal Well-Being Index (PWI) and the 5-item World Health Organization Quality of Life Assessment (WHOQoL-5) across six countries in a sample of persons with spinal cord injury (SCI).
  
  
  METHODS
  A cross-sectional multi-centre study was conducted and the data of 243 out-patients with SCI from study centers in Australia, Brazil, Canada, Israel, South Africa, and the United States were analyzed using Rasch-based methods.
  
  
  RESULTS
  The analyses showed high reliability for all 4 instruments (person reliability index .78-.92). Unidimensionality of measurement was supported for the WHOQoL-5 (Chi2 = 16.43, df = 10, p = .088), partially supported for the PWI (Chi2 = 15.62, df = 16, p = .480), but rejected for the LISAT-9 (Chi2 = 50.60, df = 18, p = .000) and the SWLS (Chi2 = 78.54, df = 10, p = .000) based on overall and item-wise Chi2 tests, principal components analyses and independent t-tests. The response scales showed the expected ordering for the WHOQoL-5 and the PWI, but not for the other two instruments. Using differential item functioning (DIF) analyses potential cross-country bias was found in two items of the SWLS and the WHOQoL-5, three items of the LISAT-9 and four items of the PWI. However, applying Rasch-based statistical methods, especially subtest analyses, it was possible to identify optimal strategies to enhance the metric properties and the cross-country equivalence of the instruments post-hoc. Following the post-hoc procedures the WHOQOL-5 and the PWI worked in a consistent and expected way in all countries.
  
  
  CONCLUSIONS
  QoL assessment using the summary scores of the WHOQOL-5 and the PWI appeared cross-culturally valid in persons with SCI. In contrast, summary scores of the LISAT-9 and the SWLS have to be interpreted with caution. The findings of the current study can be especially helpful to select instruments for international research projects in SCI.
authors.affiliation: Swiss Paraplegic Research SPF, Nottwil, Switzerland. szilvia.geyh@paranet.ch
authors.forename: Szilvia
authors.initials: S
authors.lastname: Geyh
authors.forename: Bernd A G
authors.initials: BA
authors.lastname: Fellinghauer
authors.forename: Inge
authors.initials: I
authors.lastname: Kirchberger
authors.forename: Marcel W M
authors.initials: MW
authors.lastname: Post
mesh_terms: D000328:Adult; D001315:Australia; D001938:Brazil; D002170:Canada; D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007557:Israel; D008297:Male; D008875:Middle Aged; D010549:Personal Satisfaction; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D013019:South Africa; D013119:Spinal Cord Injuries / Q000523:psychology*; D011795:Surveys and Questionnaires; D014481:United States; D014944:World Health Organization
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