Background/Purpose: The identification of erosions plays a critical role in the management of RA, as the presence of erosions denotes more aggressive disease requiring more aggressive treatment. MRI can be used to visualize and monitor erosion progression in RA, and is often used as a gold standard in research. While the clinical significance of grade 1 erosions remains unknown, so too does the trajectory of these erosions over time. This study examined the course of grade 1 erosions (involving 1-10% of bone on MRI) in the feet of newly diagnosed RA patients after two or more years of treatment.

Methods: Patients newly diagnosed with RA (treatment-naïve, ACR criteria) were recruited. Participants were assessed at baseline, 1-year, and ≥2 years (24-49 months) after diagnosis. The most clinically symptomatic foot chosen at baseline was scanned using a 1.0T peripheral MRI at each visit. A radiologist, blinded to clinical results, semi-quantitatively scored erosions in the metatarsal head and the base of the phalanges of each of MTPs 2-4 (grade 0-10) according to OMERACT-RAMRIS criteria. All patients were treated as per standard of care, and therapy received after baseline assessment was noted. The location of each erosion was noted to ensure that changes over time corresponded to the original erosion. Erosions were compared after one year and ≥2 years and categorized as unchanged, worsened or improved. New erosions were also noted.

Results: This study included 41 patients [n=33 females, mean (SD) age 51.9 (10.3) years]. The baseline MRI found at least one grade ≥1 erosion in 35 of 41 patients (85%), in 103 MTP joint bones. The majority of the erosions were grade 1 [n=89 (86%)] at baseline. Comparing grade 1 erosions one year later, 20 (19%) had resolved, 77 (75%) remained unchanged, 6 (6%) had progressed, and there were 20 new grade 1 erosions. Comparing baseline grade 1 erosions to ≥2 years later, 16 (16%) had resolved, 87 (84%) remained stable, 0 had progressed, and there were 10 new grade 1 erosions. Of note, only one erosion progressed by more than 1 grade within a follow-up period (grade 1 to grade 3 after 1 year). In terms of treatment, by their final assessment, 6 patients had received no DMARDs/biologics, 20 were on a single DMARD, 8 on combination DMARDs, and 7 on biologic or biologic/DMARD combination. There was no consistent relationship identified between the type of therapy and the improvement, stability, or progression of erosions.

Conclusion: Grade 1 erosions on MRI are common in the MTP joints of early RA patients. The majority of erosions appear to resolve or remain stable following two or more years of treatment. This suggests that early standard treatment may be sufficient to manage small erosions. There does not appear to be any consistent relationship between change in these small erosions and the type of RA treatment chosen. The clinical relevance of these erosions remains unknown.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-trajectory-of-grade-1-erosions-in-the-feet-of-patients-with-early-ra/