The clinical picture of rheumatoid arthritis according to the 2010 American College of Rheumatology/European League Against Rheumatism criteria: Is this still the same disease?

Objective To examine the implications of using the new classification criteria for rheumatoid arthritis (RA) in clinical practice in a cohort of patients with very early arthritis. Methods. The study group comprised 301 disease-modifying antirheumatic drug-naive patients with early arthritis. The baseline diagnosis was assessed by applying the 1987 American College of Rheumatology (ACR) and 2010 ACR/European League Against Rheumatism (EULAR) criteria for RA as well as established diagnostic criteria for other rheumatic diseases. Diagnostic and prognostic data were collected after 2 years of followup. Fulfillment of the 2010 ACR/EULAR criteria was evaluated in the subset of patients in whom undifferentiated arthritis (UA) was diagnosed when the 1987 ACR criteria were applied, and fulfillment of RA criteria over time was tested by applying the 2 different criteria sets. Results. The median arthritis duration at baseline was 4 months (range 0-12 months). At baseline, 28% of the patients fulfilled the 1987 ACR criteria, and 45% fulfilled the 2010 ACR/EULAR criteria for RA. Among the patients classified as having UA at baseline according to the 1987 ACR criteria, 36% had fulfilled the 2010 ACR/EULAR criteria already at baseline. Among the patients classified as having UA at baseline but who fulfilled the 1987 ACR criteria after 2 years of followup, 85% had fulfilled the 2010 ACR/EULAR criteria at baseline. Patients with early disease who fulfilled the 2010 ACR/EULAR criteria were less likely to be autoantibody positive and more likely to have monarthritis at presentation than those fulfilling the 1987 ACR criteria. Conclusion. Use of the 2010 ACR/EULAR criteria clearly allows earlier diagnosis of RA, although the clinical picture is slightly different on the group level, and RA may be falsely diagnosed in some patients with self-limiting disease.