Diagnostic value of serum and joint fluid anti-CCP (citrulline-containing peptide) antibody for rheumatoid arthritis and its relationship with other inflammatory indicators

Abstract

To investigate the diagnostic sensitivity and specificity of serum and joint fluid citrulline-containing peptide (CCP), variant antibody (anti-CCP antibody) for active rheumatoid arthritis (RA) and to explore their relationship with other clinical inflammatory indicators, the levels of serum and joint fluid anti-CCP antibodies, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and rheumatoid factors (RF) were detected in 104 active RA patients including 68 with knee joint effusion. The sensitivity of serum anti-CCP antibody to RA was 92.3% (96/104) and that of joint fluid anti-CCP antibody was 82.4% (56/68) (P>0.05). The specificity of serum and joint fluid anti-CCP antibody was 100%. There was no significant correlation between anti-CCP antibody and ESR, CRP, score of DAS28, and RF in RA patients positive for serum anti-CCP antibody (P>0.05). After treatment for half month with integrated traditional Chinese and Western medicine, all indicators were improved. The levels of ESR, CRP, RF, score of DAS28 and serum anti-CCP antibody were decreased significantly after treatment when compared with those before treatment (P<0.05). In our study, two patients with early RA (course<2 months) were negative for serum anti-CCP antibody but positive for joint fluid anti-CCP antibody, and seroconversion was noted with the prolongation of disease duration. Combination of serum anti-CCP antibody and joint fluid anti-CCP antibody is helpful for the “early diagnosis” of RA and evaluation of the severity of RA, thus providing basis for the early treatment. The negativity and positivity of anti-CCP antibody are interchangeable under certain conditions. Key words: Anti-CCP antibody, rheumatoid arthritis, early diagnosis.