Add-on iguratimod or tacrolimus in methotrexate in patients with rheumatoid arthritis not achieving remission with methotrexate: a retrospective propensity score-matched study

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. 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. 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. In this retrospective study, combination therapy with IGU or TAC added to MTX was associated with favorable efficacy and safety in patients with RA not achieving remission with MTX monotherapy.