SAT0686 Are mri-detected erosions in patients with undifferentiated arthritis predictive for the development of rheumatoid arthritis? a large longitudinal study
Authors: D.M. Boeters, A.C. Boer, A.H. van der Helm – van Mil
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Radiographic erosions are a clear hallmark of rheumatoid arthritis (RA) and the presence of radiographic erosions according to the EULAR definition is sufficient to classify patients as RA. Recently, the use of MRI has been recommended to detect erosions since it is more sensitive than radiography. To determine the specificity of MRI-detected erosions, we recently compared hand and foot MRI of patients presenting with RA with those of symptom-free persons and patients presenting with other arthritides. This revealed that many MRI-detected erosions were not specific for RA but a few erosion features were identified as specific for RA. These were grade ≥2 erosions (defined as &gt;10% of bone eroded), erosions located in MTP5, and erosions located in MTP1 in persons aged &lt;40. These results were derived by comparing patients that already received their final diagnosis. A clinically relevant question is whether MRI-detected erosions in patients presenting with undifferentiating arthritis (UA) are valuable in predicting future progression to RA. <h3>Objectives</h3> To determine whether MRI-detected erosions in patients presenting with UA are valuable in predicting future progression to RA. <h3>Methods</h3> 302 patients consecutively presenting with UA (not fulfilling the 2010-criteria) between 2010 and 2016 were studied. At baseline 1.5T MRI of the 2nd −5th metacarpophalangeal(MCP)- and 1 st −5th metatarsophalangeal(MTP)-joints was performed. Erosions were scored according to the RAMRIS system by 2 readers (ICC &gt;0.93); an erosion was considered present if both readers scored ≥1. First the presence of any MRI-detected erosion was evaluated. Then the presence of RA-specific erosions, defined as grade ≥2 erosions, erosions in MTP5 and erosions in MTP1 in persons aged &lt;40, was evaluated. Patients were followed up for 1 year on the development of RA (according to the 2010-criteria) and/or on the start of DMARDs. <h3>Results</h3> Of the 302 UA-patients 144 (48%) developed RA and/or started DMARDs. MRI-detected erosions were observed in 57% of the 2010 UA-patients but their presence was not predictive for the development of RA (OR 1.3, 95% CI 0.8–2.0, PPV 50%). RA-specific erosions (either a grade ≥2 erosion, erosion in MTP5 and/or erosion in MTP1 in persons aged &lt;40) were present in only 8% of the 2010 UA patients and were also not associated with RA-development (OR 0.9 95% CI 0.4–1.9, PPV 44%). The observed PPVs were comparable to the prior risk of 48%. Similar findings were obtained when studying the individual RA-specific erosions separately. <h3>Conclusions</h3> MRI-detected erosions were frequently present in UA-patients. In contrast, RA-specific MRI-detected erosions were rare in UA. Since MRI-detected erosions were not associated with an increased risk on progression to RA, the present data indicate that evaluation of MRI-detected erosions is not prognostically relevant in UA-patients. <h3>Disclosure of Interest</h3> None declared