Predictors for severe persisting pain in rheumatoid arthritis are associated with pain origin and appraisal of pain

Objectives: To determine the proportion of rheumatoid arthritis (RA) patients with severe persisting pain and to identify predictive factors despite treatment-controlled disease activity. Methods: This prospective multi-centre study included outpatients with RA scheduled for escalation of anti-inflammatory treatment due to active disease and severe pain (DAS28 > 3.2 and VAS > 50). At week 24, patients were stratified into reference group (DAS28 improvement > 1.2 or DAS28 ≤ 3.2 and VAS pain score < 50), non-responders (DAS28 improvement ≤ 1.2 and DAS28 > 3.2, regardless of VAS pain score), and persisting pain group (DAS28 improvement > 1.2 or DAS28 ≥ 3.2 and VAS pain score ≥ 50). The former two subgroups ended the study at week 24. The latter continued until week 48. Demographic data, DAS28-CRP, visual analogue scale for pain, painDETECT questionnaire (PD-Q) to identify neuropathic pain (NeP), and the Pain Catastrophizing Scale (PCS) were assessed and tested for relation to persisting pain. Results: Of 567 patients, 337 (59.4%) were classified as reference group, 102 (18.0%) as nonresponders, and 128 (22.6%) as patients with persisting pain. 21 (8.8%) responders, 28 (35.0%) non-responders, and 27 (26.5%) persisting pain patients tested positive for NeP at week 24. Pain catastrophising (p=0.002) and number of tender joints (p=0.004) were positively associated with persisting pain at week 24. Baseline PD-Q was not related to subsequent persisting pain. Conclusions: Persisting and non-nociceptive pain occur frequently in RA. Besides the potential involvement of NeP, pain catastrophising and a higher number of tender joints coincide with persisting pain.