# Limited discriminatory value of RAMRIS findings between RA and hand osteoarthritis: a cross-sectional MRI study

## TL;DR

This study finds that MRI scores (RAMRIS) are not very effective at distinguishing rheumatoid arthritis from hand osteoarthritis based on certain features.

## Contribution

The study reveals that RAMRIS has limited discriminatory power between RA and HOA due to overlapping MRI features.

## Key findings

- RAMRIS synovitis subscores were significantly higher in RA compared to HOA.
- BME, erosion, and tenosynovitis scores did not significantly differ between RA and HOA.
- MRI findings alone may not be sufficient to differentiate RA from HOA without clinical context.

## Abstract

To evaluate the capacity of the RA MRI Score (RAMRIS) in distinguishing rheumatoid arthritis (RA) and hand osteoarthritis (HOA). Patients with RA and HOA were retrospectively matched in pairs. Inflammatory and degenerative changes in MRI scans of the hands were quantified and compared using RAMRIS, focusing on bone marrow edema (BME), erosion, synovitis, and tenosynovitis. CRP, ESR, and autoantibodies (RF and ACPA) and clinical scores (DAS-28, FFbH, and pain level), smoking status, and medication use were assessed additionally. Overall, 100 RA and 100 HOA patients with confirmed diagnosis were included. Age, pain severity, and functional impairment did not differ between groups. RAMRIS revealed significantly higher synovitis subscores in RA compared to HOA (p<0.001), while no significant differences were found for BME (p = 0.076), erosion (p = 0.366), or tenosynovitis (p = 0.129). Higher RAMRIS scores were observed at the level of individual joints in RA. The mean erosion-subscore was found to be higher in RA males than in RA females, though this was not observed in all joints. In HOA, men exhibited a mean erosion score that was higher than that of women. Smoking status had limited association with RAMRIS findings, but RA non-smokers exhibited greater inflammatory burden than HOA non-smokers in multiple joints. RA exhibited significantly higher synovitis subscores, indicative of active inflammation and leading to overall higher RAMRIS scores, compared to HOA. However, HOA demonstrated high RAMRIS scores for synovitis, tenosynovitis, erosions, and BME. MRI may assist in distinguishing RA from HOA; however, its interpretation must be integrated into the clinical context.