Reproducibility: reliability and agreement parameters of the Revised Short McGill Pain Questionnaire Version-2 for use in patients with musculoskeletal shoulder pain

Background: The Revised Short McGill Pain Questionnaire Version-2 (SF-MPQ-2) is a multidimensional outcome measure designed to capture, evaluate and discriminate pain from neuropathic and non-neuropathic sources. A recent systematic review found insufficient psychometric data with respect to musculoskeletal (MSK) health conditions. This study aimed to describe the reproducibility (test-retest reliability and agreement) and internal consistency of the SF-MPQ-2 for use among patients with musculoskeletal shoulder pain.

Methods: Eligible patients with shoulder pain from MSK sources completed the SF-MPQ-2: at baseline (n = 195), and a subset did so again after 3-7 days (n = 48), if their response to the Global Rating of Change (GROC) scale remained unchanged. Cronbach alpha (α) and intraclass correlation coefficient (ICC_2,1), and their related 95% CI were calculated. Standard error of measurement (SEM), group and individual minimal detectable change (MDC90), and Bland-Altman (BA) plots were used to assess agreement.

Results: Cronbach α ranged from 0.83 to 0.95 suggesting very satisfactory internal consistency across the SF-MPQ-2 domains. Excellent ICC_2,1 scores were found in support of the total scale (0.95) and continuous subscale (0.92) scores; the remaining subscales displayed good ICC_2,1 scores (0.78-0.88). Bland-Altman analysis revealed no systematic bias between the test and retest scores (mean difference = 0.13-0.19). While the best agreement coefficients were seen on the total scale (SEM = 0.5; MDC_90individual = 1.2 and MDC_90group = 0.3), they were acceptable for the SF-MPQ-2 subscales (SEM: range 0.7-1; MDC_90individual: range 1.7-2.3; MDC_90group: range 0.4-0.5).

Conclusion: Good reproducibility supports the SF-MPQ-2 domains for augmented or independent use in MSK-related shoulder pain assessment, with the total scale displaying the best reproducibility coefficients. Additional research on the validity and responsiveness of the SF-MPQ-2 is still required in this population.