Background The treatment of RA with biologic (b)DMARDs should usually be combined with the non-biologic (nb)DMARD methotrexate (MTX). Randomized controlled trials showed superior efficacy of combination therapy in RA patients. Nevertheless, in daily clinical care about one third of patients have to be treated with monotherapy due to intolerability of MTX or other nbDMARDs. The effectiveness of this treatment regime has rarely been studied in unselected RA patients.

Objectives To investigate characteristics of patients treated with bDMARDs in monotherapy versus those with bDMARDs in combination with MTX and to compare treatment adherence and comedication.

Methods Patients enrolled in RABBIT with abatacept (ABA), adalimumab (ADA), etanercept (ETA) and tocilizumab (TOC) from 2007 to 2012 who had at least one follow-up (N=1937) were stratified according to their treatment with bDMARD monotherapy or bDMARD + MTX. Therapy discontinuation within the first 12 months of follow-up was examined with Kaplan-Meier methods.

Results Irrespective of the particular bDMARD, patients on monotherapy were significantly older, less frequently males, had more comorbidities, poorer physical function and were more often treated with high doses of concomitant prednisone (>10mg/day; p<0.01). Chronic renal and liver diseases were 2 to 5 times more frequent in patients on monotherapy (p<0.01; Table). There was no difference regarding treatment adherence between monotherapy and combination of bDMARDs with MTX for all agents except ADA. However, patients on monotherapy more frequently remained on higher doses of glucocorticoids after 6 months (table). For ADA, treatment continuation was significantly higher in combination with MTX (70.5/12 months [CI 65.3-75.0]) than on monotherapy (53.8 [CI 46.6-60.4]).

Conclusions A considerable proportion of severely affected patients with RA cannot be treated with MTX due to comorbid conditions. This applies in particular to older and multimorbid patients who could benefit from a similarly tolerated and effective monotherapy with the bDMARDs ABA, ETA or TOC. However, it has to be kept in mind that higher dosages of glucocorticoids were needed to reach the comparable effectiveness. For ADA, combination with MTX is advisable.

Disclosure of Interest A. Richter Grant/research support: The German Biologics Register RABBIT is supported by a joint unconditional grant from AbbVie, Bristol-Myers Squibb, MSD Sharp & Dohme, Pfizer, Roche and UCB., J. Listing: None declared, J. Kekow: None declared, S. Balzer: None declared, S. Remstedt: None declared, A. Zink: None declared, A. Strangfeld: None declared

DOI 10.1136/annrheumdis-2014-eular.3691