The clinical significance of anti-cyclic citrullinated peptide antibody in primary Sjögren syndrome

Anti-cyclic citrullinated peptide antibody (anti-CCP) is a specific marker for the diagnosis of rheumatoid arthritis. However, this antibody can be detected in other rheumatic diseases and even in healthy people. This study aims to determine the prevalence and the clinical significance of anti-CCP in patients with primary Sjögren syndrome (pSS). We analyzed the clinical and laboratory data of 95 patients with pSS by retrospective review of their medical records. Anti-CCP was measured by ELISA kit. Anti-CCP, rheumatoid factor (RF), anti-nuclear antibody, anti-Ro and anti-La antibodies, and clinical data were investigated. We analyzed clinical and serologic characteristics of anti-CCP-positive patients. Twenty-one patients (22.1%) had positive anti-CCP (mean titer 61.6 ± 15.6 U/ml) and 40 patients (42.1%) had positive RF (mean titer 98.8 ± 22.7 IU/ml). Seventy-nine patients (83.1%) had arthralgia, and 31 patients (32.6%) had non-erosive arthritis on physical examination and radiologic images. Anti-CCP-positive patients had more frequently positive RF (71.4% vs. 41.8%, P = 0.01) and anti-Ro antibody (85.7% vs. 60.8%, P = 0.03). Anti-CCP-positive patients had non-erosive arthritis more frequently than anti-CCP-negative patients (76.1% vs. 21.6%, P < 0.01). The prevalence of anti-CCP was 22.1% in pSS, and anti-CCP was associated with non-erosive arthritis, and positivity of RF and anti-Ro antibody.