Maxime Verhoeven

81 TCZ vs. TCZ+MTX; prevention of radiographic progression in RA INTRODUCTION Joint damage is a negative outcome of rheumatoid arthritis (RA), which results in declined physical function and quality of life. 1 However, preventing radiographic progression of joint damage has improved over the last decades by early intensive treat-to-target treatment strategies with disease modifying anti-rheumatic drugs (DMARDs), including biological (b)DMARDs. 1 Consequently, detection of differences in preventing radiographic progression between effective treatment strategies is challenging, especially early in the disease. 2 Nevertheless, joint damage remains an important outcome, since it objectively reflects irreversible damage, 3 and the ‘disease-modifying’ effect of treatment strategies. 4 Methotrexate (MTX) is the most frequently used first-line DMARD in RA, but patients may need to switch to, or to combine MTX with a (b)DMARD because of adverse events and/or insufficient response to MTX. It is a clinical fact that a relevant subgroup of patients doesn’t adhere to MTX treatment due to side effects, aversion or inadequate efficacy. 4 Tocilizumab (TCZ) may then be a suitable option since it can be used with lower doses of MTX, or even without MTX (i.e., as TCZ-monotherapy), while still being effective regarding disease activity as well as preventing radiographic progression. 5 However, it is not clear whether the combination of TCZ+MTX has a better effect on preventing radiographic progression than TCZ-monotherapy, although this would be relevant knowledge for clinical decision making. The aim of our study, using individual patient data (IPD), was to determine the effect of preventing radiographic progression of TCZ-monotherapy compared to TCZ+MTX combination therapy, on different components of radiographic progression, and to identify possible effect modifiers. We hypothesized that, in general, a more intensive strategy (i.e., TCZ+MTX) would increase the effectiveness of preventing radiographic progression of treatment. However, this may vary among subgroups regarding disease phase and severity. METHODS Randomized controlled trials (RCTs) in RA with at least a treatment arm with TCZ administered intravenously as monotherapy as well as a treatment arm with TCZ in combination with MTX, and assessing radiographs of hands and feet, at baseline and after two years were identified, and IPD was obtained (see Supplementary Data S1). RCTs published until January 31, 2020 were selected. The Medical Research Involving Human Subjects Act (WMO) was not applicable to this study as it concerned re-analysis of existing data. 5