| Background:Rheumatoid Arthritis ( RA ) is a systematic autoimmune disease with manifestation of progressive articular inflammation. If the patients don't receive the proper treatments at early stage, most of them will develop into joint damage and deformity. RA is described as"5D"in foreign countries, which are discomfort, distress, disability, death and dollar lost. Therefore, patients should start therapy as early as possible. Doctors should use effective disease-modifying anti-rheumatic drugs (DMARDs) in the early stage, so that disease progression can be controlled, erosive joint damage can be prevented and reduced, which is especially important to the prognosis of RA. Early diagnosis is the base of early therapy, while the present standard of RA diagnosis depends mainly on clinical manifestation, X-ray and rheumatoid factor(RF).But the sensitivity of RF is 50-90%,specificity of RF is 60%～85%,both the sensitivity and the specificity are poor. Recently, a lot of researches have shown that anti-cyclic citrullinated peptide antibody (Anti-CCP antibody), anti-perinuclear factor (APF), anti-filaggrin antibody (AFA) and anti-RA33 antibody can be tested in the early RA. These antibodies may help improving the sensitivity of RA diagnosis,especially in early stage. Objective:To evaluated anti-CCP antibody, RF, APF, AFA and anti-RA33 antibody assay for the diagnosis of RA., and analyze the significance of these antibodies in the assessment of disease activity and erosive joint damage in the patients with RA.Methods:Anti-CCP antibody, APF, AFA, RF and anti-RA33 antibody were detected in 160 serum samples: 63 from RA patients and 67 from non-RA patients, including patients with systemic lupus erythematosus , gout, osteoarthritis, ankylosing spondylitis, mixed connective tissue disease and reactive arthritis. 30 healthy donors with matched gender and age were also included. The prevalence of Anti-CCP antibody, APF, AFA, RF and anti-RA33 antibody and their diagnostic value in RA, the relationships between these antibodies and disease activity as well as erosive joint damage were analyzed.Results:1. Prevalence of Anti-CCP antibody, APF, AFA, RF and anti-RA33 antibody in RA1).The prevalence of RF, anti-CCP antibody, APF, AFA, and anti-RA33 antibody in RA were 69.8%,87.3%,55.6 %,38.1% and 27.0%.The prevalence of these autoantibodies in RA was significantly higher than that in non-RA patients and the normal controls(P<0.05).2). In the patients with disease duration less than two years, the prevalence of anti-CCP antibody was higher than that of RF (P<0.05); The prevalence of RF was higher than those of AFA and anti-RA33 antibody in the patients with disease duration more than six months, and also higher than that of APF in the patients with disease duration more than two years (P<0.05).2. The diagnostic value of anti-CCP antibody, APF, AFA, RF and anti-RA33 antibody in RA1). The sensitivity of anti-CCP antibody was higher than that of RF(X2=5.704,p=0.017).The specificity of APF (X2=3.795,p=0.045), AFA(X2=6.418,p=0.011) and anti-RA33 antibody(X2=3.795,p=0.045) was higher than that of RF respectively.2). The areas under the ROC curves of anti-CCP antibody, RF, APF, AFA and anti-RA33 antibody were 0.891,0.782,0.732,0.661,0.581,in which that of anti-CCP antibody was the highest.3).The sensitivity, specificity, positive predictive value and negative predictive value were 100%, 77.6%, 80.6%, 100%in patients with at least one antibody positive, 85.7%, 88.1%, 87.1% ,86.8% in patients with at least two antibodies positive, 54.0%,95.5%,91.9%, 68.8% in patients with more than two antibodies positive, 28.6%,100%,100% and 59.8%in patients with more than three antibodies positive, and; 9.5%,100%,100% and 54.0% in patients with all antibodies positive respectively.3. Relationships between .disease activity and autoantibodies in RA1). There is statistical difference of number of tender joint, number of swollen joint, titers of RF and DAS28 scores between anti-CCP antibody positive group and negative group.2). DAS28 scores in anti-CCP antibody positive group were higher than those in anti-CCP antibody negative group(p=0.002).Similar result was also found in RF positive group compared with negative group(p=0.005). 3).There is no statistical difference of disease activity and other parameters between positive and negative groups of APF, AFA or anti-RA33 antibody.4. Relationship between erosive joint damage and autoantibodies in RACompared with the patients with negative anti-CCP antibody and RF, patients with positive anti-CCP antibody or high titers of RF showed worse erosive joint damage(X2=8.129,p=0.004 and X2=3.860,p=0.048).Conclusion:1. Anti-CCP antibody had a good sensitivity and specificity in the diagnosis of RA. The sensitivity of anti-CCP antibody was higher than that of RF, APF, AFA and anti-RA33 antibody, especially in the early RA patients (disease duration less than two years), which suggests that anti-CCP antibodies can be used for early diagnosis of RA.2. Combined detection of RF, anti-CCP antibody, APF, AFA and anti-RA33 antibody was useful for RA diagnosis and differential diagnosis.3. The presence of anti-CCP antibody and RF correlated with worse joint involvement and erosive damage. Patients with high serum level of anti-CCP antibody and RF need intensive treatment. |
