Background/Purpose: Radiography is often used in RA clinical trials to screen for bone erosions (ERO) to ensure that only patients with the erosive phenotype are enrolled. Despite this fewer than 30% of patients in most RA cohorts show significant progression of joint damage. Osteitis (OST) and synovitis (SYN) on MRI have been shown to predict ERO progression, and may thus offer further opportunity to enrich clinical trial cohorts with patients more likely to progress structurally. However, previous studies examining these MRI parameters were at the patient level, and were thus confounded by the multiplicity of individual joint score combinations that could produce a similar total score. We have examined the association between OST and SYN at baseline and the progression of ERO on follow-up at the level of individual bones and joints in an unplanned sub-analysis of the AC-CUTE trial (NCT01951170).¹

Methods:  50 patients with active RA who had inadequate response to methotrexate (MTX) or other DMARDs and had at least one ERO on screening radiographs or MRI were included in the sub-analysis. 1.5T MRI of one hand (MCP 1-5) and wrist was acquired at baseline and 24 weeks. Two radiologists scored all images blinded to visit order using the RA MRI Score (RAMRIS); the two radiologists’ scores were averaged.

Results:  A total of 1245 bones were examined. ERO, OST and SYN at baseline were each associated with ERO progression, with odds ratios (OR) of 9.5, 3.7 and 3.1, respectively (Table). OST was more strongly associated with ERO progression than ERO or SYN were. Among bones with ERO at baseline, a larger proportion of those with concurrent OST, i.e., “active” ERO (OR = 1.6) but not those with adjacent SYN (OR = 1.0) progressed. At the patient level, the OR for progression with active ERO (ERO + OST) versus with ERO alone was 1.7. Screening for ERO originally excluded 6% of patients from participating in the study. Screening for at least one bone with active ERO would have excluded 28% more. Requiring patients also to have SYN adjacent to the bone with active ERO would have raised the screen failure rate to 42%.

Conclusion:  Baseline ERO, OST and SYN were each associated with ERO progression at the individual bone and joint level. Screening with MRI for the presence of active ERO may enrich RA trial cohorts with likely progressors more effectively than would screening for ERO, OST or SYN alone. References: 1. Bird et al. EULAR 2016, (AB0368). [DOI: 10.1136/annrheumdis-2016-eular.3780]. Table: Effect of ERO, OST and SYN at baseline on subsequent ERO progression

*Erosion progression defined as ≥0.5

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/enriching-rheumatoid-arthritis-trial-cohorts-with-erosion-progressors-by-screening-for-active-erosions-erosions-with-osteitis-with-mri/