Diagnostic Performance of the Anti-Cyclic Citrullinated Peptide Antibodies and Rheumatoid Factor Isotypes in Rheumatoid Arthritis / 임상검사와정도관리

ABSTRACT

BACKGROUND: The rheumatoid factor (RF) is the only serological marker in American College of Rheumatology criteria for the diagnosis of rheumatoid arthritis (RA), but its specificity is not satisfactory for the diagnosis of RA. We evaluated the diagnostic performance of a new anti-cyclic citrullinated peptide antibodies (anti-CCP) test with those of RF isotypes for the diagnosis of RA. METHODS: Anti-CCP was determined in 186 serum samples 110 from RA patients, 30 from non-RA patients(rheumatic diseases other than RA), and 46 normal individuals. IgM RF by latex fixation test and IgA RF by ELISA were also assayed in each samples, and the results were compared to anti-CCP for sensitivity and specificity by the receiver-operating characteristic curve on optimal cut-off values. RESULTS: The sensitivity of anti-CCP was highest (80.0%) and the sensitivities of IgM RF, IgA RF were 71.8%, 45.5%, respectively. The sensitivity increased (from 80.0% to 88.2%) especially in the combination of anti-CCP with IgM RF. The specificity of IgA RF by ELISA were highest (96.0 %) and the specificity of anti-CCP (94.7%) was higher than that of IgM RF (71.4%). Anti-CCP was positive in 58.1% in 31 RA patients with negative IgM RF. CONCLUSIONS: The results said that the combination test of anti-CCP with IgM RF might be useful for the diagnosis of RA because of its higher sensitivity and specificity than IgM RF alone.