Neuropathic-like Features and Pain Interference in Rheumatoid Arthritis: Association After Accounting for Disease Activity and Pain Severity—A Multicenter Cross-Sectional Study

Background/Objectives: Pain may persist in rheumatoid arthritis (RA) even when low disease activity or remission is recorded by DAS28-CRP. We examined whether neuropathic-like features, assessed using the complete Douleur Neuropathique 4 Questions (DN4), were associated with pain interference after accounting for DAS28-CRP disease activity and pain severity. Methods: This multicenter cross-sectional secondary analysis included 107 adults with RA and chronic pain. Pain severity and interference were calculated from the Brief Pain Inventory (BPI), and DN4 was analyzed as a continuous 0–10 score. Hierarchical linear regression with HC3 robust standard errors was fitted; 95% confidence intervals for ΔR2 were estimated from 5000 bootstrap resamples, and optimism-corrected R2 was calculated. Results: Adding BPI severity increased R2 from 0.126 to 0.529 (ΔR2 = 0.403; 95% CI 0.233–0.524), and adding DN4 increased it to 0.630 (ΔR2 = 0.101; 95% CI 0.036–0.177). In the final model, BPI severity (B = 0.548; 95% CI 0.373–0.723) and DN4 total (B = 0.366; 95% CI 0.223–0.509) were associated with greater pain interference (both p < 0.001); optimism-corrected R2 was 0.570. Conclusions: Neuropathic-like features provided additional information on pain interference beyond pain severity and RA disease activity. These cross-sectional findings quantify an adjusted within-sample association; they do not establish causality, prospective clinical utility, or a neuropathic mechanism.