Comparison of the response to infliximab or etanercept monotherapy with the response to cotherapy with methotrexate or another disease-modifying antirheumatic drug in patients with rheumatoid arthritis: results from the British Society for Rheumatology Biologics Register.

OBJECTIVE: To compare outcome at 6 months in unselected "real-world" patients with rheumatoid arthritis treated with etanercept or infliximab as either monotherapy, cotherapy with methotrexate (MTX), or cotherapy with another disease-modifying antirheumatic drug (DMARD). METHODS: A total of 2,711 subjects starting treatment with their first biologic agent (1,453 infliximab and 1,258 etanercept) were followed up for 6 months. Outcome was assessed using the European League Against Rheumatism (EULAR) response criteria. Ordinal regression was used to model the response in the MTX and other DMARD cotherapy groups relative to the monotherapy group separately for the 2 anti-tumor necrosis factor alpha agents, after adjusting for baseline differences. RESULTS: Etanercept-treated patients had an increased likelihood of achieving a higher EULAR response category with cotherapy with MTX (odds ratio [OR] 2.0, 95% confidence interval [95% CI] 1.5-2.7) and with another DMARD (OR 1.2, 95% CI 0.9-1.6) as compared with monotherapy. For infliximab-treated patients, the likelihoods were 1.4 (95% CI 0.9-2.0) for MTX and 1.3 (95% CI 0.8-2.1) for other DMARDs versus monotherapy. Cotherapy with MTX or another DMARD produced significantly higher rates of remission with etanercept (12% and 11%, respectively) as compared with etanercept monotherapy (5%). Infliximab-treated patients showed similar remission rates in the MTX and other DMARD cotherapy groups (8% and 5%, respectively) as in the monotherapy group (7%). CONCLUSION: In this study of real-world patients, the use of MTX and, to a lesser extent, other DMARDs as cotherapy with etanercept was associated with a higher likelihood of response. Although the infliximab guidelines suggest that MTX be used as cotherapy, in clinical practice, both monotherapy and cotherapy with DMARDs other than MTX are used. These data suggest that either of the latter strategies may be useful in patients who are intolerant to MTX.