title: Psychometric properties of the Oswestry disability index: Rasch analysis of responses in a work-disabled population.
abstract: BACKGROUND
  The Oswestry disability index (ODI) is the most widely used measure of perceived disability for low back conditions. It has been adopted without adaptation in functional capacity evaluation (FCE). Rigorous testing of the ODI with modern psychometric methods, in this setting, is warranted.
  
  
  OBJECTIVE
  To determine the psychometric properties of the ODI in FCE: unidimensionality; differential item functioning; item coverage and to identify poorly functioning items, allowing for improvement of these items and recalibration of the scale.
  
  
  METHODS
  Rasch analysis, specifically Masters' partial credit model, was conducted on data.
  
  
  METHODS
  133 work-disabled individuals presenting for FCE in northern British Columbia, Canada.
  
  
  RESULTS
  All items had one poorly functioning option. Items were rescaled from six categories to five, improving the psychometric properties of the ODI as a unidimensional (disability due to back pain) scale. Item difficulty range is sufficient for a population with mild to severe disability.
  
  
  CONCLUSIONS
  Although two of the ten ODI items functioned marginally unsatisfactorily in the unrevised state, the 5-option revised ODI appears superior. Use in clinical settings across a broad spectrum of disability levels could help establish its psychometric properties. Health professionals should be aware that the ODI may perform differently depending on client population.
authors: Community Health Science, University of Northern British Columbia, Prince George, BC, Canada.
authors: Lois E
authors: LE
authors: Lochhead
authors: Peter D
authors: PD
authors: MacMillan
mesh_terms: D000328:Adult; D001416:Back Pain / Q000523:psychology*; D005260:Female; D006801:Humans; D017770:Lifting; D008297:Male; D008875:Middle Aged; D011594:Psychometrics; D012725:Sexual Behavior; D012890:Sleep; D058992:Social Participation; D011795:Surveys and Questionnaires; D016138:Walking; D014938:Work Capacity Evaluation; D055815:Young Adult
keywords: Functional capacity evaluation; item analysis; low back pain; perceived ability; self-report questionnaire