Effects of Concomitant Methotrexate on Large Joint Replacement in Patients With Rheumatoid Arthritis Treated With Tumor Necrosis Factor Inhibitors: A Multicenter Retrospective Cohort Study in Japan.

Objective: To determine the effects of concomitant methotrexate (MTX) on the incidence of large joint replacement resulting from the progression of large joint destruction in patients with rheumatoid arthritis (RA) treated with tumor necrosis factor (TNF) inhibitors.

Methods: A retrospective cohort study was performed using a multicenter registry. In total, 803 patients with RA who received etanercept or adalimumab were included. The first large joint replacement during treatment with etanercept or adalimumab was used as the outcome variable in predictive analyses. The cumulative incidence of large joint replacement was estimated using Kaplan-Meier curves, and the impact of concomitant MTX on the incidence of large joint replacement was assessed with Cox proportional hazards models. Propensity score matching was used to reduce selection bias.

Results: Of all patients, 601 (75%) received concomitant MTX at a median dosage of 8 mg/week (interquartile range 6-8). A total of 49 patients (62 joints) underwent large joint replacement during treatment with etanercept or adalimumab. The incidence of large joint replacement for patients with concomitant MTX was significantly lower than that for patients without MTX (P < 0.001). Multivariate analysis revealed that concomitant MTX independently predicted large joint replacement (hazard ratio 0.36, 95% confidence interval 0.20-0.65). Additionally, propensity score-matched analysis demonstrated that patients with concomitant MTX had a significantly lower incidence of large joint replacement than those without concomitant MTX (P = 0.032).

Conclusion: Concomitant MTX reduces the incidence of large joint replacement in patients with RA treated with TNF inhibitors.