Background The new 2010 ACR/EULAR classification criteria for rheumatoid arthritis (RA) have shown good diagnostic properties in early arthritis cohorts, but it is not well known how the population of early RA identified by these criteria differs from the population of early RA according to the old criteria.
Objectives To describe clinical findings in an inception cohort of 175 DMARD naïve patients with early RA, and assess fulfillment of the 1987 ACR criteria for RA.
Methods Consecutive patients from 11 centers in Norway who fulfilled the 2010 ACR/EULAR classification criteria for RA, with symptom duration (from first swollen joint) less than 2 years, and who were DMARD naïve with indication of DMARD treatment, were recruited from Oct 2010 to Dec 2012. Patients were stratified according to level of the disease activity score (DAS) at baseline (low <2.4, moderate 2.4-3.7, high>3.7), and fulfillment of the 1987 ACR criteria as well as clinical findings were compared (pairwise comparisons by Mann-Whitney U test, T-test and Chi²-test as appropriate).
Results A total of 175 patients were included, 63.3% female, 79.7% anti-CCP pos, mean (SD) age 51.5 (13.1) years, BMI 25.8 (4.4), patient global VAS (mm) 49.8 (23.6), physician global VAS (mm) 41.1 (21.0). 36% did not fulfill the 1987 ACR criteria. The mean (SD) ACR/EULAR classification point score in patients fulfilling the 1987 ACR criteria was 7.9 (1.2) compared to 7.0 (1.1) in those who did not fulfill the criteria (p<0.001). At initiation of DMARD treatment, mean (SD) DAS was 3.5 (1.1), and 14.3 % were in low disease activity, 48.0% moderate disease activity and 37.7% high disease activity according to DAS. Among patients with low disease activity at baseline, the majority (72%) did not fulfill the 1987 ACR criteria (table). Differences in clinical characteristics were all statistically significant (table). High disease activity at baseline was associated with shorter time since the first joint swelling.
Conclusions A large proportion of patients with RA according to the 2010 criteria who had low or moderate disease activity did not fulfill the 1987 ACR criteria. This suggests that the early RA population according to the new criteria differs substantially compared to the early RA population according to the old criteria, and that the new criteria are important for early diagnosis and treatment, especially in patients with low or moderate disease activity. Patients with high DAS at baseline had shorter disease duration than patients with low or moderate DAS, suggesting that these patients had a more abrupt onset of disease.
Disclosure of Interest A.-B. Aga: None Declared, E. Lie: None Declared, T. Uhlig: None Declared, H. Hammer: None Declared, D. van der Heijde: None Declared, T. Kvien: None Declared, E. Haavardsholm Grant/research support from: Abbvie, Pfizer, MSD, Roche, UCB