Development and Validation of Rheumatoid Arthritis Magnetic Resonance Imaging Inflammation Thresholds Associated with Lack of Damage Progression

Objectives: To determine thresholds for rheumatoid arthritis (RA) magnetic resonance imaging scores (RAMRIS) associated with a low risk of structural damage progression. Methods: MRI of the dominant hand was performed and RAMRIS scores determined at weeks 0, 24, and 52. X-rays were performed and van der Heijde-Sharp scores (vdHS) determined. In a development cohort (N=297) the changes in MRI erosion score and vdHS score were determined over the 24-week to 52-week interval and progression was defined as change >0.5. We identified 24-week thresholds for synovitis and osteitis that provided >90% sensitivity for imaging progression over the 24 to 52-week interval. The performance of these cutoffs was tested in a validation cohort (N=217). Results: In the development cohort, synovitis or osteitis scores ≤3 by 24 weeks were associated with a low probability of progression on MRI and X-ray. The coefficient for osteitis was stronger than that of synovitis in models predicting X-ray and MRI progression. Therefore, a total inflammation score was weighted on osteitis (x2). An inflammation score ≤9 was more frequently attained than DAS28 remission (64 v. 38) and was associated with low probability of progression regardless of attainment of clinical remission. In the validation cohort, there was a low odds of MRI progression among those with low synovitis [OR 0.27 (0.086,0.82) p=0.02], osteitis [OR 0.20 (0.085,0.49) p<0.001] and inflammation scores [OR 0.12 (0.033,0.41) p=0.001]. Conclusion: Attainment of low MRI single-hand synovitis and osteitis is not uncommon and predicts a lack of structural progression in RA, independent of clinical remission.