RT Journal Article SR Electronic T1 Patients with seronegative RA have more inflammatory activity compared with patients with seropositive RA in an inception cohort of DMARD-naïve patients classified according to the 2010 ACR/EULAR criteria JF Annals of the Rheumatic Diseases JO Ann Rheum Dis FD BMJ Publishing Group Ltd and European League Against Rheumatism SP 341 OP 345 DO 10.1136/annrheumdis-2015-208873 VO 76 IS 2 A1 Lena Bugge Nordberg A1 Siri Lillegraven A1 Elisabeth Lie A1 Anna-Birgitte Aga A1 Inge Christoffer Olsen A1 Hilde Berner Hammer A1 Till Uhlig A1 Maria Karolina Jonsson A1 Désirée van der Heijde A1 Tore K Kvien A1 Espen Andre Haavardsholm YR 2017 UL http://ard.bmj.com/content/76/2/341.abstract AB Objectives To compare the presentation of seropositive and seronegative early rheumatoid arthritis (RA) in disease-modifying antirheumatic drug (DMARD)-naïve patients classified according to the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria.Methods All patients had symptom duration from first swollen joint <2 years and were DMARD naïve with an indication for DMARD treatment. Patients were stratified as seropositive (positive rheumatoid factor (RF)+ and/or anticitrullinated peptide antibody (ACPA)+) or seronegative (RF− and ACPA−), and disease characteristics were compared between groups.Results A total of 234 patients were included, and 36 (15.4%) were seronegative. Ultrasonography (US) scores for joints (median 55 vs 25, p<0.001) and tendons (median 3 vs 0, p<0.001), number of swollen joints (median 17 vs 8, p<0.001), disease activity score (DAS; mean 3.9 vs 3.4, p=0.03) and physician global assessment (mean 49.1 vs 38.9, p=0.006) were significantly higher in seronegative patients compared with seropositive. Total van der Heijde-modified Sharp score, Richie Articular Index and patient-reported outcome measures were similar between groups.Conclusions Seronegative patients had higher levels of inflammation, assessed both clinically and by US, than seropositive patients. These differences may reflect the high number of involved joints required for seronegative patients to fulfil the 2010 ACR/EULAR classification criteria for RA.Trial registration number NCT01205854; Pre-results.