The Detection Value Of Anti-cyclic Citrullinated Peptide Antibody For The Early Diagnosis In Patients With Rheumatoid Arthritis

IntroductionRheumatoid arthritis (RA) is a systemic inflammatory autoimmune disease of unknown etiology, characterized by chronic polyarthritis. The diagnosis of RA mainly depends on clinical manifestations. The only serologic test routinely used in RA assessment is the determination of rheumatoid factor (RF) in the serum. RF can be detected in almost 80% of RA patients, but it is also present in patients with other autoimmune disease and in the normal population at a lower frequency, which will not contribute to the early diagnosis of RA.Recent research has discovered specific autoantibodies in sera of RA patients, including anti-perinuclear factor (APF) antibodies, anti-keratin antibodies (AKA) and cytokeratin filament aggretating protein filaggrin antibodies (AFA), which specifically bind to substrates containing the modified amino acid citrulline. In 2000, it is firstly reported that the artificial synthesized cyclic citrullinated peptide (CCP) can be measured using a peptide-based enzyme-linked immunosorbent assay (ELISA) and anti-CCP antibody appeared to be very specific for RA (94%～98%), and was present in at least 60%～75% of the patients studied.The purpose of this study was to evaluate the sensitivity and specificity of anti-CCP antibody in patients with RA, explore the relationship with RF and some other clinical factors and the early prognostic value for RA. Materials and methodsSixty-one patients including 31 RA patients and 30 other rheumatic diseases were collected from October 2005 to October 2006 in the department of rheumatism immunity, Second Affiliated Hospital of China Medical University. And serum samples of 8 controls were collected from the general population participating in a physical examination.All the cases did not coexist with any clinical infectious signs and complications. We collected the information of the clinical and laboratory consequences, such as ESR, CRP, etc. By use of a sensitive ELISA, serum Anti-CCP antibody was measured in all 69 samples. Serums were stored at -20℃until used. The concentration of the anti-CCP antibody is considered positive when it was equal to or more than 5Ru/ml.Statistical analysis: The results were analyzed using T-test, Chi-square test or correlation analysis and processed by SPSS 10.0. A value P＜0.05 was considered statistically significant.Results1,The sensitivity of anti-CCP antibody was 74.91%, with a high specificity (94.74%) in RA. There was significant difference between the test group and the control group (P＜0.001).2,The sensitivity of RF was 77.42%, and the specificity was 76.31%. There was no significant difference between the sensitivity of RF and anti-CCP antibody. While the specificity of the RF was significantly lower than anti-CCP antibody (P＜0.05).3,The positive rates of anti-CCP antibody in the early arthritis patients and advanced stage arthritis patients were 61.54% and 83.33%. There is no difference between them (P＞0.05).4,There was positive correlation among serum levels of anti-CCP antibody, RF and ESR(P＜0.05), but negative with CRP (P＞0.05). ConclusionsAnti-CCP antibody has better sensitivity and specificity for rheumatoid arthritis, combining anti-CCP antibody, RF and other laboratory tests can increase diagnosis value for RA, indicating it is a useful laboratory marker for early diagnosis of rheumatoid arthritis.