Validation of the Simplified Chinese Version of the Functional Rating Index for Patients With Low Back Pain

Study Design. Cross-cultural translation and psychometric testing of the Functional Rating Index (FRI). Objective. To evaluate the reliability and validity of the adapted simplified Chinese FRI (SC-FRI) for patients with low back pain (LBP). Summary of Background Data. The FRI is a reliable and valid instrument to assess the perception of function and pain for patients with LBP. However, there is no culturally adapted, reliable, and validated FRI for use in mainland China. Methods. The translation and cross-cultural adaptation were performed following international guidelines. The SC-FRI was administered to 115 patients with LBP along with the simplified Chinese version of the Oswestry Disability Index, 36-Item Short Form Health Survey, and the visual analogue scale. Psychometric testing included internal consistency, test-test reliability, concurrent criterion validity, and construct validity. Results. A high completion rate of 96% and no floor or ceiling effects were noted for the SC-FRI. The internal consistency was good (i.e., Cronbach α = 0.897 for the overall SC-FRI; range, 0.851― 0.890, if an item was deleted). Test-retest reliability was excellent, with an intraclass correlation coefficient of 0.948 (95% confidence interval, 0.917-0.968). Concurrent criterion validity assessment demonstrated that the SC-FRI significantly correlated with the visual analogue scale (r = 0.852, P < 0.0001) and the simplified Chinese version of the Oswestry Disability Index (r = 0.958, P < 0.0001). Construct validity was confirmed by the significant Pearson correlation between the SC-FRI and Physical Functioning (r = -0.802, P < 0.0001), Bodily Pain (r = -0.698, P < 0.0001), Social Functioning (r = -0.573, P < 0.0001), Role-Physical (r = -0.503, P < 0.0001), and General Health (r = -0.502, P < 0.0001) domains of the 36-Item Short Form Health Survey. Conclusion. The SC-FRI showed excellent reliability and validity in the evaluation of pain and the functional health status of Chinese-speaking patients with LBP. It is simple and easy to use and can be recommended in clinical and research practice in mainland China.