Influence of Rheumatoid Factors on the Efficacy of TNF Inhibitor Therapy in Patients with Rheumatoid Arthritis

INTRODUCTION: Although the efficacy of tumor necrosis factor inhibitors (TNFi) is reduced in patients with rheumatoid factor (RF)-high rheumatoid arthritis (RA), certolizumab pegol (CZP), lacking the Fc portion, may not be affected. This study aimed to compare CZP with Fc-containing TNFi and investigate whether RF levels affect the efficacy of CZP in patients with RA. METHODS: This multicenter retrospective study involved patients with RA (n = 1010) who received TNFi with concomitant methotrexate (MTX). Patients were categorized by baseline RF quartiles. The primary endpoint was the Simplified Disease Activity Index (SDAI) remission rates at 26 weeks for patients treated with CZP and those receiving Fc-containing TNFi. The secondary endpoint compared the efficacy of CZP and adalimumab (ADA) in each RF quartile using propensity score-based inverse probability of treatment weighting (PS-IPTW). RESULTS: In the overall cohort, the SDAI remission rate was the lowest in Q4 (RF ≥ 136.45 IU/mL). In Q4, multivariable logistic regression analysis showed that only the introduction of CZP was significantly associated with remission at 26 weeks. The Fc-containing TNFi group had significantly lower SDAI remission rates in Q4 compared with Q1-Q3. Conversely, the SDAI remission rates were similar between the two groups treated with CZP. After PS-IPTW adjustment in Q4, CZP-treated patients showed a significantly lower SDAI and higher remission rate (36.6%) compared with the ADA-treated patients (24.5%) (p = 0.0172). No significant differences in SDAI remission rates were observed between the two groups in Q1-Q3. CONCLUSION: CZP may be more effective than Fc‑containing TNFi in patients with RA and high RF levels.