ARE ANTI-MCV ASSAYS A BETTER TOOL THAN ANTI-CCP FOR DIAGNOSIS OF RHEUMATOID ARTHRITIS?

Background: For ever 10 years, the measurement of anticitrullinated protein or peptides antibodies (ACPA) has improved the diagnosis performances in rheumatoid arthritis (RA) and several assays are now routinely used. Some studies have claimed that mutated citrullinated vimentin (MCV) antibodies could perform better than anti-cyclic citrullinated peptides- (CCP) antibodies for RA diagnosis (1) Objectives: The aim of this study was to compare the diagnosis performances for RA of five commercial EIAs detecting anti-CCP or anti-MCV antibodies Methods: Assays have been done in a cohort of 114 RA patients (median disease duration: 36 months range 1-436) and a control group (n=103), including other rheumatic diseases different from RA (n=28), patients with connective tissue diseases (n=35), infections (n=10), monoclonal gammopathy (n= 10) and healthy blood donors (n=20). For RA patients whose disease duration was less than 12 months (n = 17), diagnosis was established after a followup of 24 months. Assays were performed with serum sample aliquots stored at –30 °C and the following EIA reagents: Immunoscan RA Mark2 (Eurodiagnostica, Arnhem, The Netherlands), Bindazyme human anti-CCP2 (The Binding Site, Birmingham, UK), Elia CCP (Phadia, Uppsala, Sweden), Quanta Lite CCP 3.1 IgG-IgA (Inova Diagnostics, San Diego USA), and Anti-MCV (Orgentec Diagnostika, Mainz, Germany). The IgM RF was measured by EIA (Inova Diagnostics). Performances of kits were calculated using the Receiver Operating Curve (ROC) method, defining sensitivity, specificity and positive (+) and negative (-) likelihood ratios at manufacturer's cutoffs. Results: Results are collected in the table below AssaysSensitivity % (95% IC)Specificity % (95% IC)(+) LR(–) LR AntiCCP2 Eurodiagnostica86.0 (78.2 - 91.8)98.1 (93.1 - 99.7)44.270.14 AntiCCP2 Binding Site85.1 (77.2 - 91.1)96.1 (93.1 - 99.7)43.820.15 AntiCCP2 Phadia86 (78.2 - 91.8)97.1 (91.7 - 99.4)29.50.14 AntiCCP3.1 Inova 3.184.2 (76.2 - 90.4)99.0 (94.7 - 99.8)86.70.16 Anti MCV Orgentec78.1 (69.4 - 85.3)89.3 (81.7 - 94.5)7.310.25 RF Inova82.5 (74.2 - 88.9)67.0 (57.0 - 75.9)2.50.26 Conclusion: Sensitivity, specificity and likelihood ratios of the anti-MCV kit are lower than the ones of anti-CCP 2 or antiCCP3 kits, suggesting that anti-MCV kits did not perform better than anti-CCP in RA diagnosis. In this cohort, whether 12 out of 99 RA patients had antiCCP antibodies (Phadia) but no antiMCV, only 3 out of 89 RA patients had anti-MCV but no anti CCP. Moreover, in order to obtain a specificity value at 97%, similar to the median value of specificity from the antiCCP kits, the antiMCV cutoff level has to be increased at 33U/ml and sensitivity fell at 67.5%. References: 1. L. Mathsson et al. Arthritis Rheum. 2008. 58:36-45. Disclosure of Interest: none declaredCitation: Annals of the Rheumatic Diseases, volume 68, supplement 3, year 2009, page 416Session: Rheumatoid arthritis Comorbidity and clinical aspects (Poster Presentations )