To explore the diagnostic value of serum anti-cyclic citrullinated peptide (Anti-CCP) antibodies in patients with rheumatoid arthritis (RA).
Anti-CCP antibodies were detected in the serum samples of 120 RA patients, 71 non-RA patients with various rheumatic diseases, and 50 normal controls by enzyme-linked immunosorbent assay (ELISA) using domestic and imported commercial detection kits. Rheumatoid factors (RF) were assayed by immune-nephelometry. The correlation between Anti-CCP and RF in RA diagnosis was analyzed by calculating the area under curve of the receiver operating characteristic (ROC) curve.
The positive rates for Anti-CCP, detected using both domestic and imported kits, were 61.7% (74/120) and 69.2% (83/120) in RA group, significantly higher than those in the non-RA group (9.9%, 7/71 and 7.0%, 5/71) and normal control group (both 0, P<0.001). The sensitivities for Anti-CCP and RF were 69.2% and 64.2%, and the specificities were 92.9% and 67.6%, respectively. The positive predictive value was 94.3% for Anti-CCP and 77.0% for RF, whereas the negative predictive value was 64.1% for Anti-CCP and 52.7% for RF. The likelihood ratio (LR) was 9.82 for anti-CCP and 1.98 for RF. The area under curve of ROC for Anti-CCP was 0.829 and 0.740 for RF. Anti-CCP antibodies had greater diagnostic value than RF in RA diagnosis, and Anti-CCP showed significant correlation with RF (r=0.29, P=0.001).
Anti-CCP antibodies are an excellent serological marker for RA, which shows high diagnostic specificity at early stage, and can increase its diagnostic value when combined with RF detection, but the role of Anti-CCP in the occurrence and prognosis of RA remains to be further investigated.