Outcomes in recent‐onset inflammatory polyarthritis differ according to initial titers, persistence over time, and specificity of the autoantibodies

Objective To prospectively evaluate the predictive value of initial titers and subsequent variations of 3 rheumatoid arthritis–associated antibodies for outcomes at 30 months in patients with recent‐onset polyarthritis. Methods IgM rheumatoid factor (RF), anti‐Sa (citrullinated vimentin) antibodies, anti–cyclic citrullinated peptide 2 (anti–CCP‐2) antibodies, modified Health Assessment Questionnaire score, Disease Activity Score in 28 joints, and Sharp/van der Heijde radiologic scores were determined at baseline and at 18 and 30 months in a cohort of consecutive HLA–DR‐typed treated patients with recent‐onset polyarthritis aiming at remission. Results At inclusion, 113 (44.7%), 58 (22.9%), and 97 (38.3%) of 253 recent‐onset polyarthritis patients were positive for RF, anti‐Sa, and anti–CCP‐2, respectively; at 30 months, 85 (33.6%), 31 (12.4%), and 100 (39.5%) patients were similarly positive. A low titer of any particular antibody was associated with higher risks for seroreversion. Similar to their persistent absence, reversion of RF and anti–CCP‐2 was associated with low risks for severity. Patients who acquired RF or anti–CCP‐2 after inclusion trended toward a poor prognosis. Relative to RF and anti–CCP‐2 antibodies, only the presence of anti‐Sa at inclusion, especially at higher titers and even when it subsequently disappeared, significantly predicted more rapid radiographic damage and lower remission rates at 30 months. Conclusion In treated recent‐onset polyarthritis, anti–CCP‐2 prevalence is stable or increases slightly, whereas anti‐Sa and RF frequently disappear. Subsequent reversion and conversion of RF and anti–CCP‐2 blur the prognostic significance of initial RF and anti–CCP‐2 positivity. Of the 3 antibodies, only anti‐Sa, even if it disappears afterward, independently predicts severe outcomes.