Background MRI is currently the imaging gold standard reference for visualization of the inflammatory status of the affected joints in patients with rheumatoid arthritis (RA) . The OMERACT-RA MRI Scoring System (RAMRIS)  is the recommended MRI scoring method for clinical trials. The reliability of this system has been evaluated in a number of studies , but its ability to predict the clinical effect of biological treatment is not yet clarified.
Objectives To investigate the ability of the OMERACT RAMRIS synovitis score, to predict the clinical outcome (EULAR response) of biologic treatment after 6 months on therapy.
Methods All RA patients starting biological therapy at Frederiksberg Hospital between 2006 and 2010 with a valid MRI scan of the dominant wrist before initiation of biological therapy, and a record available in the DANBIO registry, were included. Clinical data at baseline and 6 months follow-up were extracted from the DANBIO registry. The MRI was scored according to the OMERACT-RAMRIS criteria. Patients were grouped into high (>6) or low-moderate (≤6) synovitis score, and the Relative Risk (RR, with 95% CI) for treatment response according to the EULAR response criteria was calculated. Missing data were replaced by non-responder imputation.
Results 106 patients fulfilled the inclusion criteria; 61% received infliximab, 30% etanercept, 7% adalimumab, 1% rituximab and 1% tocilizumab. Of these, 76 had low-moderate and 30 high MRI synovitis score. Patients in the high-synovitis group had significantly higher clinical disease activity at baseline (DAS28 (median (interquartile range)) = 5.4 (4.7 -6.1) vs. 4.7 (4.1-5.3) p= 0.005), but were also older, had longer disease duration and a higher MRI bone edema and bone erosion score. 86 patients completed the study. The likelihood of responding in the high synovitis group vs. the low-to-moderate synovitis group was RR=1.30 (0.75-2.24, p=0.35) for a good EULAR response, 1.55 (0.83-2.89, p=0.170) for a moderate EULAR, and the high synovitis group had a significantly lower risk of not responding to treatment (RR=0.25 (0.06-0.98), p=0.046; EULAR no response).
Conclusions High OMERACT- RAMRIS scores for synovitis in the wrist joint are related to high overall clinical disease activity. Lower pre-treatment MRI synovitis score was associated with lower clinical effect after 6 months of biological treatment in RA patients.
Boesen, M., et al., MRI quantification of rheumatoid arthritis: current knowledge and future perspectives. Eur J Radiol, 2009.
Ostergaard, M., et al., OMERACT Rheumatoid Arthritis Magnetic Resonance Imaging Studies. Core set of MRI acquisitions, joint pathology definitions, and the OMERACT RA-MRI scoring system. J Rheumatol, 2003.
Disclosure of Interest None Declared