Reliability, Concurrent Validity, and Clinical Performances of the Shorter Version of the Roland Morris Disability Questionnaire in a Sample of Italian People with Non-Specific Low Back Pain

Background: Evaluating the psychometric and clinical performances of the RM-18, the shorter version of the Roland Morris Disability Questionnaire (RMQ), in Italian people with non-specific low back pain (NSLBP) as a time-saving and clinically useful method of assessing disability. Methods: This cross-sectional study included 74 people (52 females and 22 males, 53.03 ± 15.25 years old) with NSLBP. The RM-18, the RMQ, the Oswestry Disability Index (ODI), and a pain intensity numerical rating scale (NRS) were administered. Psychometric testing included reliability by internal consistency (Cronbach's alpha) and test-retest measurement (Intraclass Correlation Coefficient, ICC2.1), and concurrent validity by comparing the RM-18 with the RMQ and the ODI (Pearson's r correlation). Two separate regression analyses were performed to investigate the different impact of RM-18 and RMQ on NRS. Results: Cronbach's α of RM-18 was 0.92 and ICC (2,1) = 0.96. Strong correlations were found with the RMQ and the ODI (r = 0.98; r = 0.78, respectively). The regression models showed that the RM-18 and the RMQ similarly impacted the NRS (p < 0.001). Conclusion: The RM-18 showed satisfactory psychometric testing and similarly impacted the NRS when compared to the RMQ. It can be recommended for clinical and research purposes in Italian people with NSLBP.