To investigate the frequency of remaining pain in early rheumatoid arthritis (RA) after 3 months of treatment with methotrexate as the only disease modifying antirheumatic drug, with a special focus on patients with a good clinical response.
The study base was cases reported to a population-based early RA cohort who had followup data from the Swedish Rheumatology Quality Register (n = 1,241). The Disease Activity Score in 28 joints European League Against Rheumatism (EULAR) response criteria were used to evaluate clinical response to treatment as good, moderate, and no response. The primary end point was remaining pain at the 3-months followup visit, defined as pain >20 mm on a 100-mm visual analog scale (VAS).
Remaining pain in spite of a EULAR good response at followup was associated with higher baseline disability, using the Health Assessment Questionnaire (adjusted odds ratio [OR] 2.2 [95% confidence interval (95% CI) 1.4-3.4] per unit increase), and less baseline inflammation, using the erythrocyte sedimentation rate (adjusted OR 0.81 [95% CI 0.70-0.93] per 10-mm increase). Similar associations were detected for remaining pain at followup in spite of low inflammatory activity, defined as a C-reactive protein level <10. Increase in VAS pain during the treatment period was observed in 19% of the whole cohort, with frequencies in the EULAR response groups of 9% (good response), 15% (moderate response), and 45% (no response).
These results are in line with the hypothesis that a subgroup of early RA patients exhibits pain that is not inflammatory mediated, where alternative treatment strategies to traditional antiinflammatory medications need to be considered.