title: The Oxford Shoulder Instability Score; validation in Dutch and first-time assessment of its smallest detectable change.
abstract: BACKGROUND
  The Oxford Shoulder Instability Score (OSIS) is a short, self-reported outcome measurement for patients with shoulder instability. In this study, the OSIS was validated in Dutch by testing the internal consistency, reliability, measurement error, validity and the floor and ceiling effects, and its smallest detectable change (SDC) was calculated.
  
  
  METHODS
  A total of 138 patients were included. Internal consistency was calculated with Cronbach's α. Reliability (test-retest) was calculated with the intraclass correlation coefficient (ICC). The measurement error was calculated (SEM), and the SDC was estimated in a subgroup of 99 patients that completed the re-test after a mean of 13 days (5-30 days). Construct validity was evaluated by comparing the OSIS with the Western Ontario Shoulder Instability index (WOSI), the Simple Shoulder Test (SST), the Oxford Shoulder Score (OSS), the Disability of the Arm, Shoulder, and Hand assessment (DASH), and the Short Form-36 (SF-36).
  
  
  RESULTS
  Internal consistency was good, with a Cronbach's α of 0.88. The reliability was excellent, with an ICC of 0.87. The SEM was 3.3 and the SDC was 9 points (on a scale of 0-48). Regarding the construct validity, 80% of the results were in accordance with the hypotheses, including a high correlation (0.82) with the WOSI. No floor or ceiling effects were found.
  
  
  CONCLUSIONS
  The Dutch version of the OSIS showed good reliability and validity in a cohort of patients with shoulder instability.
authors.affiliation: Department of Orthopedic Surgery and Traumatology, Onze Lieve Vrouwe Gasthuis, Postbus 95500, 1090 HM, Amsterdam, The Netherlands. javdlinde@gmail.com.
authors.forename: Just A
authors.initials: JA
authors.lastname: van der Linde
authors.affiliation: Department of Orthopedic Surgery and Traumatology, Waterland Ziekenhuis, Purmerend, The Netherlands. derkvankampen@gmail.com.
authors.forename: Derk A
authors.initials: DA
authors.lastname: van Kampen
authors.affiliation: Department of Orthopedic Surgery and Traumatology, Onze Lieve Vrouwe Gasthuis, Postbus 95500, 1090 HM, Amsterdam, The Netherlands. L.W.A.H.vanBeers@olvg.nl.
authors.forename: Loes W A H
authors.initials: LW
authors.lastname: van Beers
authors.affiliation: Department of Orthopedic Surgery and Traumatology, Onze Lieve Vrouwe Gasthuis, Postbus 95500, 1090 HM, Amsterdam, The Netherlands. D.F.P.vanDeurzen@olvg.nl.
authors.forename: Derek F P
authors.initials: DF
authors.lastname: van Deurzen
authors.affiliation: Department of Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research, VU Medical Center, Amsterdam, The Netherlands. cb.terwee@vumc.nl.
authors.forename: Caroline B
authors.initials: CB
authors.lastname: Terwee
authors.affiliation: Department of Orthopedic Surgery and Traumatology, De Lairesse Kliniek, Amsterdam, The Netherlands. w.j.willems@xs4all.nl.
authors.forename: W Jaap
authors.initials: WJ
authors.lastname: Willems
mesh_terms: D000293:Adolescent; D000328:Adult; D003431:Cross-Cultural Comparison; D005260:Female; D006306:Health Surveys / Q000592:standards; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D019303:Multilingualism; D009426:Netherlands / Q000453:epidemiology; D015203:Reproducibility of Results; D012785:Shoulder Joint / Q000473:pathology*; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult