title: The Oswestry Disability Index (version 2.1a): validation of a Dutch language version.
abstract: METHODS
  A cross-sectional study on baseline data.
  
  
  OBJECTIVE
  To translate the Oswestry Disability Index (ODI) version 2.1a into the Dutch language and to validate its use in a cohort of patients with chronic low back pain in secondary spine care.
  
  
  BACKGROUND
  Patient-reported outcome measures (PROMs) are commonly accepted to evaluate the outcome of spine interventions. Functional status is an important outcome in spine research. The ODI is a recommended condition-specific patient-reported outcome measure used to evaluate functional status in patients with back pain. As yet, no formal translated Dutch version exists.
  
  
  METHODS
  The ODI was translated according to established guidelines. The final version was built into the electronic web-based system in addition with the Roland Morris Disability Questionnaire, the numeric rating scale for pain severity, 36-Item Short Form Health Survey Questionnaire for quality of life, and the hospital anxiety and depression scale. Baseline data were used of 244 patients with chronic low back pain who participated in a combined physical and psychological program. Floor and ceiling effects, internal consistency, and the construct validity were evaluated using quality criteria.
  
  
  RESULTS
  The mean ODI (standard deviation) was 39.6 (12.3); minimum 6, maximum 70. Most of the participants (88%) were moderately to severely disabled. Factor analysis determined a 1-factor structure (36% explained variance) and the homogeneity of ODI items is shown (Cronbach α = 0.79). The construct validity is supported as all (6:6) the a priori hypotheses were confirmed. Moreover, the ODI and Roland Morris Disability Questionnaire, showed a strong significant correlation (r = 0.68, P < 0.001) and an overlap: mean difference of -18 (95% limits of agreement: -44 to 8).
  
  
  CONCLUSIONS
  The Dutch ODI version 2.1a is a valid and valuable tool for the measurement of functional status and disability among Dutch patients with chronic low back pain. This translated condition-specific patient-reported outcome measure version is recommended for use in future back pain research and to evaluate outcome of back care in the Netherlands.
authors.affiliation: *Departments of Research and †Orthopedics, Sint Maartenskliniek, GM Nijmegen, The Netherlands ‡Nuffield Department of Orthopaedics, Rheumatology, and Musculoskeletal Science, University of Oxford, Nuffield Orthopaedic Centre, Oxford, United Kingdom §Achmea Health Insurance Company, AW Zeist, The Netherlands; and ¶Department of Neurosurgery, Leiden University Medical Center, RC Leiden, The Netherlands.
authors.forename: Miranda L
authors.initials: ML
authors.lastname: van Hooff
authors.forename: Maarten
authors.initials: M
authors.lastname: Spruit
authors.forename: Jeremy C T
authors.initials: JC
authors.lastname: Fairbank
authors.forename: Jacques
authors.initials: J
authors.lastname: van Limbeek
authors.forename: Wilco C H
authors.initials: WC
authors.lastname: Jacobs
mesh_terms: D000328:Adult; D000368:Aged; D003431:Cross-Cultural Comparison; D004185:Disability Evaluation; D006233:Persons with Disabilities; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D010147:Pain Measurement; D010808:Physical Examination; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D014177:Translations; D055815:Young Adult