Neuropathic pain and central sensitization in patients with rheumatoid arthritis attending a tertiary hospital

BACKGROUND: In rheumatoid arthritis (RA), the persistence of pain despite adequate inflammatory control may indicate the involvement of nociplastic and/or neuropathic pain (NP). OBJECTIVE: To investigate the presence of central sensitization (CS) and/or NP in patients with RA. METHODS: This descriptive, cross-sectional study used convenience sampling and included adult patients (≥ 18 years) with RA diagnosed according to the 2010 classification criteria of the American College of Rheumatology - ACR. The following instruments were applied: Central Sensitization Inventory (CSI), PainDETECT Questionnaire (PD-Q), and the 2010/2011 ACR criteria for fibromyalgia (FM), revised in 2016 (the latter applied only to patients with CSI ≥ 40). Descriptive and predictive analyses were conducted with a significance level of 5%. RESULTS: A total of 113 patients were included (mean age 54.3 years; 93.81% female; mean disease duration 12.11 years). CS was identified in 59.29% of patients; among them, 47.76% met FM criteria, while 52.24% did not. Among patients with CS, 53.73% reported severe pain (Numeric Rating Scale, NRS), and 44.78% had high disease activity (Clinical Disease Activity Index, CDAI). CSI was a significant predictor of both NRS and CDAI in univariate (p < 0.001) and multivariate analyses (p = 0.037 and p = 0.009, respectively). According to PD-Q, 17.70% of patients had probable NP, and PD-Q scores were predictive of CDAI, NRS, and CSI (p < 0.001). Among patients with CS, 26.87% also showed overlapping NP. CONCLUSIONS: A substantial proportion of RA patients presented with CS-related pain, even in the absence of FM, suggesting a mixed ("top-down and bottom-up") nociplastic pain profile. Both CS and NP were associated with higher pain levels and increased disease activity. This is the first Brazilian study to characterize the coexistence of CS-related pain (with or without FM) and NP in RA, offering relevant insights for the clinical management of chronic pain in this population. These findings reinforce that routine screening and assessment of CS and NP should be an integral and continuous component of RA management, preceding therapeutic adjustments and extending throughout follow-up.