title: Measurement properties of the Dutch version of the Western Ontario Shoulder Instability Index (WOSI).
abstract: BACKGROUND
  The Western Ontario Shoulder Instability Index (WOSI) is a disease-specific shoulder questionnaire to measure quality of life in patients with shoulder instability. The aim of the present study was to translate the WOSI into Dutch and assess its principal measurement properties.
  
  
  METHODS
  The WOSI was translated into Dutch according to guidelines in the literature. Fifty-two shoulder instability patients completed the questionnaire twice within 2 weeks. We assessed internal consistency (Cronbach's alpha), test-retest reliability [Intraclass Correlation Coefficient (ICC)], standard error of measurement (SEM), smallest detectable change (SDC) and reliable change index. The Bland-Altman analysis was applied to assess test-retest agreement and floor and ceiling effects were calculated.
  
  
  RESULTS
  Cronbach's alpha was 0.95 for the total WOSI score (range 0.88-0.95 for the 4 domains). ICC for the total WOSI score was 0.91 (range 0.79-0.90 for domains), SEM was 130.6 for the total WOSI score resulting in a SDC of 362.0, which is 17.3 % of the maximum obtainable score of 2100. Bland-Altman analysis showed no systematic differences or consistent bias between the two assessments. We observed no relevant floor and ceiling effects.
  
  
  CONCLUSIONS
  The results of the present study suggest the Dutch version of the WOSI is a reliable tool for clinical assessment and scientific evaluation. It shows high values for Cronbach's alpha and ICC implying excellent internal consistency and good test-retest reliability.
authors.affiliation: Department of Rehabilitation Medicine, VU University Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands. Electronic address: s.wiertsema@vumc.nl.
authors.forename: Suzanne H
authors.initials: SH
authors.lastname: Wiertsema
authors.affiliation: Department of Rehabilitation Medicine, VU University Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands.
authors.forename: Marc B
authors.initials: MB
authors.lastname: Rietberg
authors.affiliation: Department of Rehabilitation Medicine, VU University Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands.
authors.forename: Karin M
authors.initials: KM
authors.lastname: Hekman
authors.affiliation: Department of Rehabilitation Medicine, VU University Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands.
authors.forename: Maaike
authors.initials: M
authors.lastname: Schothorst
authors.affiliation: Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Pieter Bas
authors.initials: PB
authors.lastname: de Witte
authors.affiliation: Institute for Applied Health Research and School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK.
authors.forename: Martijn P
authors.initials: MP
authors.lastname: Steultjens
authors.affiliation: Department of Rehabilitation Medicine and EMGO Institute, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: Dekker
mesh_terms: D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009864:Ontario; D011594:Psychometrics / Q000379:methods*; D011788:Quality of Life; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012785:Shoulder Joint / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D014175:Translating; D055815:Young Adult