Validation of the Croatian version of the Oswestry Disability Index.

PURPOSE: To translate, cross-culturally adapt, and validate the Croatian version of the Oswestry Disability Index (ODI).

METHODS

The original English-language ODI was cross-culturally adapted into Croatian and then evaluated in a group of 114 patients with chronic low back pain (LBP) at the Department of Neurosurgery, Zagreb University School of Medicine. Confirmatory factor analysis (CFA) was conducted with three models: two were theory driven (unidimensional and two dimensional-static and dynamic factors); the other was based on our exploratory factor analysis (EFA). Internal consistency and test-retest reliability were evaluated using Cronbach's α and the intraclass correlation coefficient (ICC), respectively. Construct validity was assessed by evaluating the correlation between the ODI and Visual Analogue Scale (VAS), and between the ODI and 36-item short form survey (SF-36) scores.

RESULTS

The EFA-derived two-dimensional structure explained 82.7% of the total variance and was significantly better than the other models (P < 0.001); however, none of the models had acceptable fit. Internal consistency (Cronbach α = 0.84) and test-retest reliability (ICC = 0.94) were satisfactory. The ODI was positively correlated with VAS (rs = 0.54, P < 0.001) and negatively correlated with all of the SF-36 sections (rs = - 0.35 to - 0.64, P < 0.001, all), apart from the role-physical (rs = - 0.02, P = 0.767).

CONCLUSIONS

The Croatian version of the ODI has acceptable psychometric properties. It appears to be suitable for assessment of LBP and treatment outcomes in Croatian-speaking patients. Overall, there was no evidence to reject the original unidimensional structure in favor of a two-factor solution. As such, the unidimensional structure should continue to be used in future studies. These slides can be retrieved under Electronic Supplementary Material.