Measurement Properties of the Hong Kong Chinese Version of the Roland-Morris Disability Questionnaire

Abstract 

There is a paucity of locally developed functional status measures to assess the disability of patients with low back pain. This study sought to adapt a well-known disability measure with good psychometric properties for local use. A Hong Kong Chinese version of the Roland-Morris Disability Questionnaire (RMDQ-HK) was produced by forward and backward translations of the original questionnaire. The reliability, validity and responsiveness of the RMDQ-HK were examined in 112 patients with low back pain attending 11 physiotherapy outpatient departments of the Hong Kong Hospital Authority. Item analysis showed that all except one item had satisfactory discriminative ability. The test-retest reliability of the RMDQ-HK was 0.94 (intraclass correlation coefficient, ICC[1,1]; 95% confidence interval, CI, 0.90-0.97). Its internal consistency was 0.86 (Kuder-Richardson 20 coefficient; 95% CI, 0.82-0.89). A change of 4 RMDQ-HK points with 95% CI indicated a true change rather than random variation. The standardized response mean of the RMDQ-HK was 1.22. Using a criterion of at least 70% improvement in overall condition for clinically important change from treatment commencement to discharge, change scores of 3, 6 and 9 RMDQ-HK points were considered clinically important for patients initially with mild (RMDQ-HK, 0-8), moderate (RMDQ-HK, 9-16) and high (RMDQ-HK, 17-24) severity, respectively. However, there was little correlation between mean change in RMDQ-HK score and global rating of change in overall condition at discharge (r_s = −0.22, p = 0.02). Greater correlation was obtained between the mean change score of pain rating and the global rating of change (r_s = −0.44, p < 0.001). Patients might have based the rating of their change in overall condition at discharge more on change in pain intensity than on change in functional disability. Overall, the test-retest reliability, internal consistency and responsiveness of the RMDQ-HK were high. Further investigations of the content validity and construct validity of the RMDQ-HK are recommended.

Key words:  functional status measure , Roland-Morris Disability Questionnaire , low back pain

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