Background The development of the 2010 classification criteria for rheumatoid arthritis (RA) has led to a redefinition of the patient population, including classification of seropositive versus seronegative patients. In our recently published study of DMARD naïve early RA patients fulfilling the 2010 ACR/EULAR criteria, we found seronegative patients to have markedly higher disease activity at time of diagnosis, compared to seropositive patients.[1] There is very limited information about the disease course of seronegative patients classified according to the new criteria.

Objectives Our aim was to examine the disease course of seronegative early RA patients fulfilling the 2010 ACR/EULAR criteria.

Methods In the treat-to-target ARCTIC trial, DMARD-naive RA patients classified according to the 2010 EULAR/ACR criteria were randomised 1:1 to follow-up with or without ultrasound. Patients in both arms were treated according to the same DMARD escalation strategy. Patients were assessed at 13 visits during two years of follow-up.[2] We stratified the patients as seropositive (rheumatoid factor (RF)+, anti-citrullinated peptide antibody (ACPA)+, or both) or seronegative (RF- and ACPA-). At 24-month follow-up, measures of disease activity were compared across the groups using independent samples t-test, Mann-Whitney U test or chi square test as appropriate.

Results A total of 230 patients were included, the mean (SD) age was 51.4 (13.7) years and 61.3% were female; 34 patients (14.8%) were seronegative. The mean age (SD) was 55.4 (2.7)/ 50.8 (0.9) years (p=0.07), mean (SD) disease duration was 7.7 (6.8)/7.0 (5.1) months (p=0.46), and 56/62% were females (p=0.48) in the seronegative/seropositive groups. At 24-month follow-up, measures of disease activity were similar between groups (table). There was a tendency towards more radiographic damage in the seronegative patients. Seronegative patients had a significantly greater reduction (0–24 months) in disease activity measures in terms of DAS, number of swollen joints, physician global and ultrasonography scores (table).

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Conclusions In this study of early RA patients, seronegative patients had more inflammatory activity at baseline and a tendency to more radiographic damage, but disease activity after two years of treat-to-target therapy was similar to the seropositive patients. Our findings suggest that seronegative patients classified according to the new criteria respond to modern treatment strategies, with similar rates of patients reaching remission compared to seropositive patients.

References

1. Nordberg LB et al. Annals of the rheumatic diseases 2017;76:341–345.

2. Haavardsholm EA et al., BMJ 2016;354:i4205.

References

Disclosure of Interest L. Nordberg: None declared, S. Lillegraven: None declared, A.-B. Aga: None declared, I. Olsen: None declared, E. Lie: None declared, H. Hammer Consultant for: AbbVie, Pfizer, BMS, Roche, UCB, T. Uhlig: None declared, D. van der Heijde: None declared, T. Kvien: None declared, E. Haavardsholm Grant/research support from: Pfizer, MSD, UCB, AbbVie, Roche