Diagnostic value of the anti-Sa antibody compared with the anti-cyclic citrullinated peptide antibody in rheumatoid arthritis.

AIM: To evaluate the prevalence and diagnostic significance of the autoantibody against citrullinated vimentin (anti-Sa) compared with the widely used anti-cyclic citrullinated peptide autoantibody (anti-CCP) in patients with rheumatoid arthritis (RA).
METHOD: One hundred and sixty-nine patients hospitalized at the Department of Rheumatology and Internal Medicine, Poznan University of Medical Sciences, Poznań, Poland, were enrolled in a cross-sectional study and divided into two groups. The RA group comprised 41 patients diagnosed as having RA. The non-RA control group included 128 individuals with a variety of rheumatic disorders. Serum anti-Sa and anti-CCP measurements were performed by enzyme-linked immunosorbent assay.
RESULTS: The sensitivity and specificity of anti-Sa for the diagnosis of RA was 36.6% and 96.9%, respectively. For the anti-CCP test, the sensitivity was 65.9% and the specificity was 95.3%. Concomitant presence of anti-Sa and anti-CCP was determined in 36.6% of the patients with RA, whereas isolated positivity of anti-Sa was not observed. Anti-Sa positive RA patients had significantly higher anti-CCP levels compared to anti-Sa negative subjects (P < 0.05).
CONCLUSION: With regard to the relatively low diagnostic sensitivity and the lack of cases identified by anti-Sa alone, we were unable to demonstrate any additional diagnostic value of the anti-Sa autoantibody in comparison to the anti-CCP autoantibody. To the authors' best knowledge, this is the first study among Polish patients verifying the clinical utility of anti-Sa in the diagnosis of RA.