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 cut-offs 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 vs. 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].

CONCLUSIONS

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.