SAT0675 The role of erosions typical of rheumatoid arthritis in the 2010 acr/eular rheumatoid classification criteria: results from a very early arthritis cohort

Background A EULAR task force has proposed that in addition to the 2010 ACR/EULAR rheumatoid arthritis (RA) classification criteria (2010 RA criteria), patients can still be classified as having RA with less than 6 criteria points on the presence of ≥3 joints with typical erosions on conventional radiographs of hands and feet (erosion criterion) (1). Objectives To determine how the EULAR definition of erosive disease contributes to the number of patients classified as RA according to the 2010 RA criteria in an early arthritis cohort. Methods Patients with arthritis of ≤16 weeks duration and a clinical diagnosis of RA or undifferentiated arthritis (UA) with available hand and feet radiographs were included from the Norwegian Very Early Arthritis Clinic (NOR-VEAC) study. Erosive disease was defined according to the EULAR definition accompanying the 2010 RA criteria, i.e. ≥3 erosive joints (1). We calculated the additional number of patients being classified as RA based on the erosion criteria at baseline and during follow-up. Other cut-offs and the distribution of erosive joints was also examined. Results The current study included 289 patients (mean (SD) age 48 (14.7) years, 54.3% females, median (25, 75 perc) duration of joint swelling 46 (19.5, 79.0) days). At baseline, 120 patients (41.5%) fulfilled the 2010 RA criteria. Of the remaining 169 not fulfilling the 2010 RA criteria, 55 patients had ≥1 erosive joint (40 with hand erosions, 28 with feet erosions and 13 with hand and feet erosions) and 15 (5.2%) patients fulfilled the erosion criterion (Figure 1). The distribution of erosive joints in the 169 patients not fulfilling the 2010 RA criteria at baseline is shown in the table. 118 patients had radiographic follow-up at 2 years, of whom only 1 additional patient solely fulfilled the erosion criterion during follow-up (7 additional patients fulfilled both the 2010 criteria and the erosion criterion). Among patients with no erosions at baseline (N=74), 13 (17.6%) developed erosions during follow-up (PIP joints n=3, MCP n=4, wrist n=3, CMC joint n=1, MTP joints n=9 and IP1 joint in the foot n=3). Conclusions Among this cohort of patients with very early arthritis, 5.2% were classified as RA at baseline based solely on the erosion criterion. Of the 118 patients with 2-year follow-up data, only 1 additional patient was classified based on the erosion criterion alone during follow-up, thus, follow-up radiographs in patients with early UA do not seem to provide additional information in classifying patients with RA. References van der Heijde D, van der Helm-van Mil AH, Aletaha D, Bingham CO, Burmester GR, Dougados M, et al. EULAR definition of erosive disease in light of the 2010 ACR/EULAR rheumatoid arthritis classification criteria. Ann Rheum Dis2013 Apr;72(4):479–81. Disclosure of Interest G. Brinkmann: None declared, E. Norli: None declared, P. Boyesen: None declared, D. van der Heijde: None declared, L. Grovle: None declared, A. Haugen: None declared, H. Nygaard: None declared, O. Bjorneboe: None declared, C. Thunem: None declared, T. Kvien Consultant for: Has received fees for speaking and/ or consulting from AbbVie, Biogen, BMS, Boehringer Ingelheim, Celltrion, Eli Lilly, Epirus, Janssen, Merck-Serono, MSD, Mundipharma, Novartis, Oktal, Orion Pharma, Hospira/Pfizer, Roche, Sandoz and UCB, M. Mjaavatten: None declared, E. Lie: None declared