Concurrent validity of pain scales in individuals with myofascial pain and fibromyalgia.

OBJECTIVE: Clinicians and researchers often use the numeric pain rating scale (NPRS) and visual analog scale (VAS) to measure and track pain in individuals with myofascial pain syndrome (MPS) and fibromyalgia (FM). The VAS is often used as a reference standard in chronic pain research. To date, no studies have specifically measured the concurrent validity of the NPRS and VAS in these individuals. The purpose of this investigation was to determine the concurrent validity of the NPRS when compared to the reference standard VAS in patients with MPS and FM.

METHODS: This investigation explored the concurrent validity of the NPRS and VAS in sixty participants with MPS (N = 30) and FM (N = 30). All participants underwent one day of testing using the American College of Rheumatology criteria for classifying FM. For each tender point (18-total), participants graded tenderness using the NPRS and VAS.

RESULTS: An excellent relationship was found between the NPRS and VAS for the MPS group (rho≥0.81, 95% CI 0.79-0.85, p < 0.001) and the FM group (rho ≥0.96, 95% CI 0.92-0.97, p < 0.001).

CONCLUSION: The results of this study suggest that the NPRS has good concurrent validity with the referenced standard VAS among individuals with MPS and FM.