Markers of progression to rheumatoid arthritis: discriminative value of the new ACR/EULAR rheumatoid arthritis criteria in a Portuguese population with early polyarthritis.

Objectives: Our goal was to test the performance of the new American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria for the classification of rheumatoid arthritis (RA) in a cohort of patients with very recent onset polyarthritis.

Patients: Untreated polyarthritis patients with less than 6 weeks of duration were enrolled. All patients were followed-up in order to establish a definitive diagnosis.

Results: Thirty-seven patients were included. During the follow up 57% of the patients evolved to RA. The median age of the RA-group patients was simi­lar to the median age of the non-RA group [median (IQR) 47 (31-58.5) vs 43 (34-69) years, p=0.74]. At the initial visit the DAS 28 in the RA group was significantly higher than in the non-RA group, as well as the visual analogue scale (VAS), the HAQ and the number of swollen joints. Among the 21 RA patients, 43% presented RF and 28.6% presented anti-citrullinated protein antibody (ACPA) in the first visit. RF and ACPA were not detectable in any of the patients who did not evolve to RA. According to the new ACR/EULAR criteria, the mean total score of the RA group at baseline was significantly higher than the non-RA group [median (IQR) 6 (4.5-8) vs 4.5 (2.2-6), p=0.007].

Conclusion: In our cohort high DAS28, swollen joint count, VAS and HAQ and the presence of RF or ACPA were eventually associated with the evolution into RA. The new ACR/EULAR criteria for the classification of RA seem to perform well in very early RA.