Anti-cyclic citrullinated peptide antibodies in rheumatoid arthritis and Behçet's disease.

Rheumatoid arthritis (RA) is associated with progressive joint destruction and disability. Early diagnosis of RA is important, since early and aggressive treatments lead to a better outcome. Circulating autoantibodies are a serological hallmark of systemic rheumatic diseases. More recently, antibodies directed to a cyclic citrullinated peptide, anti-CCP antibodies, have been established as specific diagnostic and prognostic tools for RA. The aims of this study were to assess the diagnostic and radiological prognostic value of the anti-CCP antibody in Turkish patients with RA (n = 97) and those with Behçet's disease (BD) (n = 46). The study also included 35 healthy controls. Anti-CCP antibodies were measured by ELISA, and radiological damage was evaluated by using modified Larsen scoring. In the RA group, sensitivity and specificity were 80.4% and 93.5% for rheumatoid factor (RF), and 74.2% and 97.8% for anti-CCP antibody, respectively. RF was positive in 3 BD patients (6.5%) and in one of the controls (2.9%). In contrast, anti-CCP antibodies were detected in one BD patient (2.2%), but not in the control subjects. Deformed joint counts and radiographic scores were higher in anti-CCP antibody-positive RA patients (n = 72) than those in anti-CCP antibody-negative patients (n = 25) (p < 0.05). Moreover, anti-CCP antibody titer correlated with deformed joint count (r = 0.224, p < 0.05) and radiographic score (r = 0.308, p < 0.05). This study indicates the diagnostic and prognostic utility of anti-CCP antibodies in Turkish patients with RA. Importantly, anti-CCP antibodies are not associated with BD.