The effect of concomitant hand osteoarthritis on pain and disease activity in patients with rheumatoid arthritis

Introduction Pain is a core complaint among rheumatoid arthritis (RA) patients, and persistent pain requires treatment adjustments according to current strategies. We aimed to quantify the impact of hand osteoarthritis (OA) on health status and residual pain in patients with RA. Methods This cross-sectional survey compared RA patients with and without osteoarthritis of the hand. The main outcome was pain intensity. Other measurements included disease activity scores (the Disease Activity Score 28-joints; the Simplified Disease Activity Index, SDAI; the Clinical Disease Activity Index, CDAI), functional disability and self-reported quality of life, and the proportion of patients with residual pain (Patient Acceptable Symptom State, PASS). Results Eighty-one patients were analyzed, including 39 with RA and OA and 42 with RA only. The patients were mainly women (94%), with a median disease duration of 13 years. This group also reported a higher intensity of pain (visual analogue scale, VAS 70 mm vs. 30 mm; p = 0.003), higher disease activity (3.89 vs. 2.88; p = 0.001), and greater functional disability irrespective of treatment and comorbidities. A strong correlation (r(2) = 0.69; p < 0.001) between pain and disease activity was observed, although no differences in pain were observed between groups according to disease activity categories. Patients with RA and OA had a higher proportion of residual pain (59% vs. 29%; p = 0.006) even in the absence of clinical inflammation. Conclusion The coexistence of RA and hand OA is associated with distorted disease activity measurements in RA. Osteoarthritis contributes to persistent pain and greater disability in patients with RA.