Structural and Criterion Validity of a New 6-item Roland–Morris Disability Questionnaire (RMDQ-6) on Patients with Chronic Lower Back Pain Receiving Integrative Medicine

Abstract

Background: Lower back pain (LBP) is a leading cause of disability worldwide. The Roland–Morris Disability Questionnaire (RMDQ) has been widely used to assess functional impairment in patients with LBP. However, its length and redundancy calls for a more concise and optimized version.Methods: We conducted a secondary analysis of data from two randomized controlled trials comparing pharmacopuncture and physical therapy for chronic LBP. We focused on 132 patients with moderate-to-severe symptoms and analyzed their baseline data to evaluate the structural validity of the RMDQ. We used R packages lavaan and semPlot for confirmatory factor analysis (CFA). Model fit were assessed through various indices, including comparative fit index, Tucker–Lewis index, root mean square error of approximation, and standardized root mean squared residual.Results: A total of 18 items were ultimately removed to produce a streamlined 6-item structure. Our model met the fit index criteria, yielding a one-domain, 6-item RMDQ structure. While the relative indices fell slightly short of the ideal values, the RMDQ-6 derived through CFA correlated well with the original version.Conclusion: This study developed a more concise version of RMDQ through CFA to optimize its structural configuration. This concise instrument can be proposed as an efficient tool to assess the functionality of patients with LBP.