OBJECTIVE: The increased prevalence of rheumatoid factor (RF) in patients with chronic hepatitis C virus (HCV) infection markedly diminishes the diagnostic specificity of serum rheumatoid factor (RF) for rheumatoid arthritis (RA) in patients with HCV. Cyclic citrullinated peptide (CCP) antibody, a highly specific biomarker for RA in the general population, may have better diagnostic utility for RA in the HCV population. To investigate if CCP antibody retains its specificity for RA in HCV infection, we determined the prevalence of CCP antibodies and examined the relationship between RF production and CCP antibody levels in a population of nonarthritic patients with chronic HCV infection. METHODS: CCP antibody and IgM, IgG, and IgA RF isotypes were determined by ELISA in serum from nonarthritic patients with chronic HCV infection. RESULTS: In a series of 50 HCV patients, IgG-RF, IgM-RF, and IgA-RF were detectable in 52%, 26%, and 14%, respectively, with a total seropositivity rate of 54%. Marginally elevated CCP antibody was detected in a single patient (2%). By regression analysis, serum levels of CCP antibodies did not correlate with RF levels. CONCLUSION: In contrast to RF, CCP antibody is not increased in HCV infection. CCP antibody may have improved utility for the diagnosis of RA in this patient population.
OBJECTIVE: The increased prevalence of rheumatoid factor (RF) in patients with chronic hepatitis C virus (HCV) infection markedly diminishes the diagnostic specificity of serum rheumatoid factor (RF) for rheumatoid arthritis (RA) in patients with HCV. Cyclic citrullinated peptide (CCP) antibody, a highly specific biomarker for RA in the general population, may have better diagnostic utility for RA in the HCV population. To investigate if CCP antibody retains its specificity for RA in HCV infection, we determined the prevalence of CCP antibodies and examined the relationship between RF production and CCP antibody levels in a population of nonarthritic patients with chronic HCV infection. METHODS: CCP antibody and IgM, IgG, and IgA RF isotypes were determined by ELISA in serum from nonarthritic patients with chronic HCV infection. RESULTS: In a series of 50 HCVpatients, IgG-RF, IgM-RF, and IgA-RF were detectable in 52%, 26%, and 14%, respectively, with a total seropositivity rate of 54%. Marginally elevated CCP antibody was detected in a single patient (2%). By regression analysis, serum levels of CCP antibodies did not correlate with RF levels. CONCLUSION: In contrast to RF, CCP antibody is not increased in HCV infection. CCP antibody may have improved utility for the diagnosis of RA in this patient population.