Add-on Iguratimod or Tacrolimus in Methotrexate Inadequate Rheumatoid Arthritis: Efficacy, Safety and Propensity Score-Matched Analysis

Background To evaluate the efficacy and safety of combination therapy with iguratimod (IGU) versus tacrolimus (TAC) plus methotrexate (MTX) in patients with rheumatoid arthritis (RA) who failed to achieve remission with MTX monotherapy. Methods This retrospective, single-centre study included RA patients treated with IGU + MTX (n = 56) and TAC + MTX (n = 52). Propensity score matching generated two balanced cohorts (n = 30 per group). The primary endpoint was the Simplified Disease Activity Index (SDAI) remission rate at week 52. Secondary outcomes included disease activity parameters, drug retention rates, and safety profiles over 52 weeks. Results Both regimens substantially improved disease activity from baseline. In the matched analysis, SDAI remission rates at week 52 were similar between IGU and TAC (43.3% vs 46.7%, p =  1.00), as were drug retention rates (70.0% vs 76.7%, p =  0.62). The TAC group showed numerically larger reductions in SDAI, Clinical Disease Activity Index, and C-reactive protein, though these differences were not statistically significant. Treatment discontinuations due to adverse events were infrequent, and both combinations were well tolerated. Conclusions Combination therapies with IGU + MTX and TAC + MTX are both effective and safe treatment options for RA patients who failed to achieve remission with MTX monotherapy. These findings support the use of conventional synthetic disease-modifying anti-rheumatic drug combinations as valuable alternatives for MTX-inadequate responders, particularly those with low disease activity, safety concerns, or economic constraints.