Objective To determine how the European League Against Rheumatism (EULAR) definition of erosive disease (erosion criterion) contributes to the number of patients classified as rheumatoid arthritis (RA) according to the 2010 American College of Rheumatology/EULAR RA classification criteria (2010 RA criteria) in an early arthritis cohort.
Methods Patients from the observational study Norwegian Very Early Arthritis Clinic with joint swelling ≤16 weeks, a clinical diagnosis of RA or undifferentiated arthritis, and radiographs of hands and feet were included. Erosive disease was defined according to the EULAR definition accompanying the 2010 RA criteria. We calculated the additional number of patients being classified as RA based on the erosion criteria at baseline and during follow-up.
Results Of the 289 included patients, 120 (41.5%) fulfilled the 2010 RA criteria, whereas 15 (5.2%) fulfilled only the erosion criterion at baseline. 118 patients had radiographic follow-up at 2 years, of whom 6.8% fulfilled the 2010 RA criteria and only one patient fulfilled solely the erosion criterion during follow-up.
Conclusion Few patients with early arthritis were classified as RA based on solely the erosion criteria, and of those who did almost all did so at baseline.
- early rheumatoid arthritis
- outcomes research
- disease activity
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Handling editor Gerd R Burmester
Contributors GHB, ESN, MDM, DvdH, TKK and EL contributed to the study design, including formulation of the research questions. GHB, ESN, MDM and EL were responsible for analysing and interpreting the data, and drafting the manuscript. All authors critically revised the manuscript and approved the final version.
Competing interests None declared.
Patient consent Obtained.
Ethics approval The Regional Ethics Committee of Southern Norway.
Provenance and peer review Not commissioned; externally peer reviewed.