LAUSR

Background: Rheumatoid arthritis (RA) is an autoimmune disease presenting by chronic joint inflammation. Early diagnosis and therapy of RA are crucial for avoiding joint damage and functional disability. HCV related arthropathy (HCVrA) is one of the RA mimics that is detected in around 52.2% of HCV patients.(1) The discrimination between HCVrA and RA is a challenge especially in early onset RA because of their similar manifestations. Detection of certain serologic markers in sera of arthritis patients could be helpful to differentiate between both types of arthritis. Besides RF and ACPA, anti-Carbamylated Protein (anti-CarP) antibodies were described for their role in early identification of RA, as they can be found in up to 45% of early RA patients. Moreover, they can be detected in ACPA-negative RA patients.(2) Objectives: To determine the role of anti-CarP antibodies in the differentiation between RA and HCVrA. Methods: This study was carried out on 4 groups: Group I:20 patients with chronic HCV infection, group II :20 Patients with HCVrA, group III :20 Patients with RA fulfilling the 2010 (ACR/EULAR) classification criteria and group IV: 20 Patients with both chronic HCV infection and RA. All patients were subjected to detailed history taking and musculoskeletal examination. Routine laboratory investigations were done for all patients in addition to ESR,CRP, RF, ACPA and anti-CarP antibodies. Plain X ray hands and feet were performed to all patients with arthritis. Results: · Morning stiffness, joint erosions in plain X-rays, inflammatory markers, ACPA and anti-CarP antibodies were significant differentiating points between RA and HCVrA (p<0.001, p<0.001, p=0.008, p<0.001 and p<0.001, respectively), while the differences between RA and HCVrA groups regarding symmetry of joint symptoms and level of RF were not significant (p=0.507, p=0.110, respectively). Table: Comparison between groups II and III according to serological markers Anti-CarP antibodies were detected in the sera of 12.5% of HCV patients (10% with and 15% without articular symptoms) in comparison to 75% of RA patients. The difference between the two groups was statistically significant (p<0.001). ACPA were detected at low titers in 15% of HCV patients (with and without articular involvement). There was a significant positive correlation between RF and anti–CarP antibodies (r= 0.386) and between ACPA and anti–CarP antibodies in the total sample studied (r =0.393). Conclusion: The presence of anti-CarP antibodies together with clinical features could discriminate RA patients from HCVrA patients. The detection of ACPA and anti-CarP antibodies in few HCV patients should be interpreted with caution. Simaltaneous detection of both anti-CCP and ani-CarP antibodies could be of great value in differentiating RA from other mimicking conditions like HCVrA. References [1] Cacoub P. et al. Medicine2000;79(1):47-56. [2] Shi J, et al. Proc Natl Acad Sci2011;108(42):17372-7. Disclosure of Interests: None declared