Validation of the Chinese version of the Oswestry Disability Index

This study aimed to collect evidence on the structural and substantive validity, and test-retest reliability of the Chinese version of the Oswestry Disability Index (CODI). Seventy-nine patients suffering from chronic low back pain were assessed with the CODI. The results of explorative factor analysis primarily suggested a single-factor structure with nine out of 10 items (factor loading = 0.66-0.79). The sex life item was found to load on a different factor. The Cronbach's alpha of all 10 items was 0.81 (p<0.05). When the sex life item was removed from the analysis, the alpha value was increased to 0.89 (p<0.05). The test-retest reliability was estimated based on 56 participants who completed two administrations of CODI in 48 hours. The intraclass correlation coefficient (ICC) computed for the total CODI scores was 0.86 (95% C.I. = 0.81-0.91). The reliability estimated for the item scores using Kappa statistics ranged from a high of k=0.80 for the sitting item to a low of k=0.49 for the traveling item. Kappa statistics were not available for three items. The Chinese version of the Oswestry Disability Index demonstrated satisfactory validity and test-retest reliability, and so could be considered as an appropriate instrument for assessing chronic back pain-related disability in Chinese patients in Hong Kong. Further research should address the cross-cultural and measurement issues in regard to sex life in order to further improve the test content of the instrument.