The positivity of rheumatoid factor and anti-cyclic citrullinated peptide antibody in nonarthritic patients with chronic hepatitis C infection.

Chronic hepatitis C virus (HCV) has extrahepatic autoimmune properties and a variety of autoantibodies were found in patients with HCV. Patients with HCV infection may have rheumatic symptoms and signs, and 50-70% of the cases may contain rheumatoid factor (RF). The increased prevalence of RF in patients with HCV infection diminishes the diagnostic specificity of serum RF for rheumatoid arthritis (RA) in patients with HCV. Therefore, the presence of RF mostly does not help in distinguishing between RA and HCV-associated rheumatic symptoms. In this study, we studied whether cyclic citrullinated peptide (CCP) antibody, a highly specific biomarker for RA in the general population, was useful for the diagnosis of RA in nonarthritic patients with HCV (hepatitis C virus). Blood samples from 39 patients with chronic HCV infection, 87 normal sera from volunteer blood donors and 108 blood samples from patients with rheumatoid arthritis, from the rheumatology clinic, were taken. RF was measured using the Dade-Behring nephelometer and antibodies to CCP were measured with ELISA. According to statistical analysis, the sensitivity, specificity and positive predictive value of the anti-CCP test was superior to the RF test. Cyclic citrullinated peptide antibody is a more useful test than RF among patients with chronic HCV infection without arthritis.