Assessing pain from different perspectives: evaluation of three pain measures in rheumatoid arthritis patients

Objective: Pain is one of the most important outcomes in RA. Therefore, as objective as possible assessment of pain is necessary for reliable clinical evaluation and effective treatment planning. The purpose of the present study was to evaluate three pain measures in the sample of 151 newly-diagnosed RA-patients. More specifically, this study evaluates the construct validity of pain instruments and examines relationships between pain, disease activity, disability and psychological well-being. Methods: In this study pain was assessed using the Nottingham Health Profile (NHP), the Ritchie Articular Index (RAI) and the McGill Pain Questionnaire (MPQ). Results: The results of factor analysis support the empirical validity of the NHP and the RAI. The factor structure of the MPQ is less clear. Furthermore, the pain instruments were found to be sensitive enough to differentiate between Steinbrocker’s functional capacity groups. The outcomes of multiple regression analysis reveal that pain, as assessed by each of the pain instruments, is strongly associated with disability. Pain as measured by the NHP is associated with psychological well-being, whereas pain as measured by the RAI is associated with disease activity. Conclusion: The results of the present investigation provide support for the construct validity of pain measures in patients with early RA. In addition, the outcomes shed more light on specific qualities of these instruments, indicating that each of the three measures assesses pain from a different perspective.