The Diagnostic Value of Anti-CCP and Rheumatoid Factor for Patients with Refractory Rheumatoid Arthritis (RA) and RA in Remission

Abstract

To compare the diagnostic value of antibodies to cyclic citrullinated peptides (anti-CCP) and rheumatoid factor (RF) for patients with refractory rheumatoid arthritis (RA) and RA in remission. Methods. A total of one hundred and forty three participants were enrolled: fifty one patients with RA refractory to standard methotrexate therapy, group I (Gr I, refractory RA); forty three RA patients in complete remission status for at least 3 months, group II (Gr II, RA in remission); and forty nine community-based healthy controls, group III (Gr III). Levels of anti-CCP and RF were measured for all of the subjects. The sensitivity and specificity of both tests were determined via these subjects. The receiver operating characteristic (ROC) analysis was used to display the pairs of sensitivity and specificity for different cut off points of anti-CCP and RF. False negative rate and the complementary diagnostic effect of both assays were also calculated and compared. Results. The sensitivity of anti-CCP and RF for Gr I were 84% and 78%, and 74% and 67% for Gr II, respectively. The specificity of anti-CCP and RF was 98% and 92% respectively. The ROC analysis disclosed that anti-CCP, compared to RF, provided the best combination of sensitivity and specificity for detecting either groups of RA. In addition, anti-CCP provided better complementary diagnostic effect for our RA patients when the results of opposite tests were negative (33% vs 11% in Gr I, and 29% vs 9% in Gr II) (p＜0.001). Conclusion. The detection of anti-CCP in the diagnosis of patients with refractory RA and RA in remission showed higher sensitivity and specificity than RF assay.