Safety and Effectiveness of 6 Months' Etanercept Monotherapy and Combination Therapy in Japanese Patients with Rheumatoid Arthritis: Effect of Concomitant Disease-modifying Antirheumatic Drugs

Objective. To assess real-world safety, tolerability, and effectiveness of etanercept monotherapy, etanercept plus methotrexate (MTX), or etanercept plus other disease-modifying antirheumatic drugs (DMARD) in Japanese patients with active rheumatoid arthritis (RA) despite previous treatment with DMARD. Methods. In this 24-week, all-cases postmarketing surveillance study, adverse events (AE) were coded using the Medical Dictionary for Regulatory Activities. Effectiveness was assessed every 4 weeks using the 28-joint Disease Activity Score and the European League Against Rheumatism response criteria. Results. Of 13,861 patients (81% women) in the analysis, 3616, 2506, and 7739, respectively, were classified into etanercept monotherapy (ETN-mono), etanercept plus DMARD other than MTX (ETN + DMARD), and etanercept plus MTX (ETN + MTX) groups. Rates of AE and serious AE (SAE) in the ETN + MTX group were lower than in other groups. Risk of SAE or serious infections was not significantly increased with higher versus lower MTX doses at baseline or with concomitant use of salazosulfapyridine or bucillamine in ETN + DMARD versus ETN-mono groups. A greater likelihood of achieving clinical remission was seen with ETN + MTX versus ETN-mono (OR 1.36; 95% CI, 1.16-1.60; p<0.001). Higher MTX dose at baseline was associated with a higher remission rate (>8 mg vs 0 to <= 4 mg, OR 1.47,95% CI 1.07-2.00, p = 0.016; 6 to <= 8 mg vs 0 to <= 4 mg, OR 1.27, 95% CI 1.01-1.60, p = 0.038). Conclusion. Combination therapies with etanercept plus MTX or other DMARD were reasonably well tolerated, and ETN + MTX at higher doses was more effective than ETN-mono in Japanese patients with RA.