Background/Purpose: Pain is the symptom with the most significant impact on patients’ lives in rheumatoid arthritis (RA), whereas 17% of German RA patients report severe pain [1, 2]. Although RA patients may no longer report pain due to an articular, inflammatory origin, neuropathic pain (NP) may compromise anti-rheumatic treatment success as well.

The data-analysis presented aimed to investigate the proportion of RA patients with persisting pain and suggest clinical practice implications given specified patient-reported outcomes.

Methods: The PAIN-CONTROL study is a prospective, non-interventional, multicenter study in specialized rheumatology centers across Germany. Patients had to fulfill these inclusion criteria: 2010 ACR/EULAR classification criteria for RA, disease duration < 8 yrs, Disease Activity Index 28 (DAS28) ≥ 3.2, SJC ≥ 3, CRP above the reference range, and a visual analog scale (VAS, 0-100) pain rating ≥ 50. Eligible subjects had to be scheduled for initiation or escalation of anti-inflammatory treatment. At wk 24, clinical outcomes were evaluated, and subjects were allocated to three subgroups: Group 1 (reference): DAS28 improvement > 1.2 or DAS28 ≤ 3.2, VAS pain < 50; group 2 (non-responders): DAS28 improvement ≤ 1.2 or DAS28 > 3.2 with or without alleviation of pain; group 3 (persisting pain): DAS28 improvement > 1.2 or DAS28 ≤ 3.2, VAS pain ≥ 50. For subjects in groups 1 and 2, the study ended at wk 24, subjects in group 3 continued until wk 48. This descriptive, interim analysis includes subjects having completed the study until Sept. 30th 2020, and informs about subjects classified as having NP by a painDETECT questionnaire (PDQ) score of ≥ 19. The attainment of a patient acceptable symptom state (i.e., Rheumatoid Arthritis Impact of Disease (RAID-PASS) score ≤ 2), and the proportion of patients with moderate depressive symptoms or worse according to the Patient Health Questionnaire 9 (i.e., PHQ-9 ≥ 10) were specified as secondary outcomes of interest. Descriptive results are presented as mean±SD or n (%), respectively.

Results: Sample characteristics (N=263) at baseline were as follows: Age 57.6 ± 13.0 yrs, disease duration 2.4 ± 2.6yrs, DAS28(CRP) 5.3 ± 0.8 with 174(66.2%) female subjects. At wk 24, the proportion of subjects who tested positive for NP in group 3 (persisting pain) was similar to group 2 (non-responder), (N=18; 25.0%) vs. (N=15; 25.9%). The number of patients with NP in group 3 decreased until wk 48, (N=10; 19.6%). Between wks 24 and 48, the number of subjects in group 3 attaining RAID-PASS increased from N=6 (8.3%) to N=12 (23.5%). Simultaneously, their DAS28(CRP) decreased from 3.4 ± 1.0 to 2.9 ± 1.2, respectively. During this period of the study, the proportion of patients in group 3 with moderate depressive symptoms or worse hardly changed (wk 24: 10(13.9%), wk 48: 7(13.7%)). For details see table 1.

Conclusion: NP is a frequent underrated challenge in RA patients either not responding to anti-inflammatory treatment or patients with persisting pain. These patient groups are likely to benefit from a multi-disciplinary treatment approach, including tailored pain management.

1. Bischoff S et al. Annual Report – National Database, 2012, DRFZ, Germany

2. Gossec L et al. Ann Rheum Dis. 2009 Nov;68(11):1680–5

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/persisting-pain-in-rheumatoid-arthritis-an-essential-yet-underrated-challenge/