Development of a German version of the Oswestry Disability Index. Part 1: cross-cultural adaptation, reliability, and validity.
Patient-orientated assessment methods are of paramount importance in the evaluation of treatment outcome. The Oswestry Disability Index (ODI) is one of the condition-specific questionnaires recommended for use with back pain patients. To date, no German version has been published in the peer-reviewed literature. A cross-cultural adaptation of the ODI for the German language was carried out, according to established guidelines. One hundred patients with chronic low-back pain (35 conservative, 65 surgical) completed a questionnaire booklet containing the newly translated ODI, along with a 0-10 pain visual analogue scale (VAS), the Roland Morris Disability Questionnaire, and Likert scales for disability, medication intake and pain frequency [to assess ODI's construct (convergent) validity]. Thirty-nine of these patients completed a second questionnaire within 2 weeks (to assess test-retest reliability). The intraclass correlation coefficient for the test-retest reliability of the questionnaire was 0.96. In test-retest, 74% of the individual questions were answered identically, and 21% just one grade higher or lower. The standard error of measurement (SEM) was 3.4, giving a "minimum detectable change" (MDC(95%)) for the ODI of approximately 9 points, i.e. the minimum change in an individual's score required to be considered "real change" (with 95% confidence) over and above measurement error. The ODI scores correlated with VAS pain intensity (r = 0.78, P < 0.001) and Roland Morris scores (r = 0.80, P < 0.001). The mean baseline ODI scores differed significantly between the surgical and conservative patients (P < 0.001), and between the different categories of the Likert scales for disability, medication use and pain frequency (in each case P < 0.001). Our German version of the Oswestry questionnaire is reliable and valid, and shows psychometric characteristics as good as, if not better than, the original English version. It should represent a valuable tool for use in future patient-orientated outcome studies in German-speaking lands.
Mannion
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AF
Schulthess Klinik, Lengghalde 2, 8008, Zürich, Switzerland. anne.mannion@kws.ch
Junge
A
A
Fairbank
J C T
JC
Dvorak
J
J
Grob
D
D
D000222:Adaptation, Physiological; D015331:Cohort Studies; D003431:Cross-Cultural Comparison; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000706:statistics & numerical data*; D005260:Female; D005858:Germany; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis* / Q000453:epidemiology / Q000534:rehabilitation; D008297:Male; D010147:Pain Measurement; D011594:Psychometrics; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D014177:Translations