Impact of etanercept on the progression of undifferentiated arthritis to rheumatoid arthritis: A prospective observational study in China.

This study explores the association between tumor necrosis factor (TNF) antagonist therapy and the progression from undifferentiated arthritis (UA) to rheumatoid arthritis (RA). This single-center prospective observational real-world study enrolled 70 patients with UA (baseline score ≥ 8) at Xingtai People's Hospital (May-December 2020). After propensity score matching (1:1), 64 patients were matched; 4 lost to follow-up were excluded, leaving 60 for final analysis. Patients received MTX monotherapy or etanercept + MTX. Between-group differences were assessed using the Mann-Whitney U test, chi-square test, or Fisher exact test. Survival was analyzed using Kaplan-Meier curves and log-rank tests, and independent prognostic factors were identified through multivariable Cox regression. A total of 60 patients (30 per group) were included in the final analysis. During the 3-year follow-up, patients in the etanercept + MTX group had a significantly lower risk of progression to RA compared with the MTX monotherapy group (6/30 [20.0%] vs 14/30 [46.7%]; log-rank P = .012). After adjusting for potential confounders, combination therapy remained independently associated with reduced progression risk (HR = 0.28, 95% CI: 0.10-0.83, P = .022). Clinical remission at 3 years was achieved in 25 of 30 patients (83.3%) in the combination group, compared to 17 of 30 (56.7%) in the monotherapy group (P = .024). In this exploratory real-world observational study, initial treatment with etanercept + MTX was associated with a lower observed risk of progression to RA and a higher observed rate of clinical remission than MTX monotherapy in high-risk UA patients. These findings should be considered hypothesis-generating and require confirmation in adequately powered randomized controlled trials in diverse populations.