The Sa autoantigen can be found in inflamed synovium of patients with rheumatoid arthritis (RA), and at least part of the humoral RA‐specific anti‐Sa response is directed against citrullinated vimentin. This study was undertaken to evaluate the sensitivity, specificity, and prognostic value of determination of levels of antibodies against modified citrullinated vimentin (anti‐MCV) as compared with antibodies against cyclic citrullinated peptides (anti‐CCP) in an inception cohort of patients with early RA.

Clinical data, radiographs, and measurements of levels of anti‐MCV and anti‐CCP antibodies were obtained in 273 patients with early RA at baseline, after 3 months, and after 1, 2, 3, and 5 years. Autoantibodies were also analyzed in 100 healthy controls.

Of the 273 patients, 193 (70.7%) were anti‐MCV positive and 158 (57.9%) were anti‐CCP positive at the time of diagnosis, with nearly equal specificities (95% and 96%, respectively). Forty (14.7%) were anti‐MCV positive only, and 5 (1.8%) were anti‐CCP positive only. Anti‐MCV–positive and anti‐MCV–negative patients had similar disease activity at baseline, but presence of anti‐MCV was predictive of subsequent high disease activity and continued radiographic progression. Changes in anti‐MCV level showed stronger correlation with changes in clinical parameters than did changes in anti‐CCP level. The subgroup of patients who were anti‐MCV positive and anti‐CCP negative showed a higher rate of radiographic destruction than did patients who were negative for both anti‐MCV and anti‐CCP.

These findings show that when patients with early RA are compared with healthy controls, analysis of anti‐MCV yields greater sensitivity and unchanged specificity as compared with analysis of anti‐CCP. Anti‐MCV also appears to perform better than anti‐CCP in identifying poor radiographic prognosis in patients with early RA.