Associations Between Changes in Pain Sensitization and Disease Activity Following Disease-Modifying Antirheumatic Drug Therapy in Established Rheumatoid Arthritis.

Objective: Abnormalities in pain regulatory mechanisms are common in patients with rheumatoid arthritis (RA). We investigated whether pain sensitization changes after treatment with a disease-modifying antirheumatic drug (DMARD) and explored associations between changes in pain sensitization and disease activity.

Methods: We included 182 participants with active RA initiating/switching DMARD therapy who were observed for 12 weeks. To assess pain sensitization, participants underwent quantitative sensory testing (QST), including pressure pain thresholds (PPTs) at multiple anatomic sites, temporal summation (TS) at the wrist and forearm, and conditioned pain modulation (CPM). RA disease activity was measured using the Disease Activity Score 28 with C-reactive protein (DAS28-CRP) and its components. Mean changes in QST measures were examined from baseline to 12 weeks, and associations between QST and disease activity measures were explored using Pearson correlation coefficients and adjusted linear regression analyses.

Results: PPTs significantly increased (improved) at multiple anatomic sites following 12 weeks of DMARD therapy. No significant changes were observed in TS or CPM. Increased PPTs at multiple anatomic sites were associated with reductions in DAS28-CRP, swollen joint count, tender joint count, and improvements in patient global assessment. No significant associations were observed between TS, CPM, and disease activity.

Conclusion: Pain sensitivity improved after 12 weeks of DMARD therapy. These improvements were associated with reductions in disease activity.