AB0500 CLINICAL CHARACTERISTICS AND POTENTIAL BIOMARKERS FOR DISEASE ACTIVITY OF PATIENTS WITH ANCA ASSOCIATED VASCULITIS: A MONOCENTER STUDY IN CHINA

Background: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) are a group of multisystem, autoimmune, inflammatory disease characterized by pauci- necrotizing vasculitis affecting small blood vessels. The clinical manifestations of the AAV are diverse and can be confined to one organ, or multiple organs and even life-threatening. However, there has been no specific index for assessing the activity of AAV at diagnosis. Objectives: The aim of this study was to describe the clinical and serological features of patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in eastern China using data from a hospital-based study. And looking for indicators that can predict disease activity. Methods: We retrospectively studied patients with newly diagnosed AAV evaluated from January 1, 2009, to December 31, 2018. In total, 219 patients diagnosed were classified according to the American College of Rheumatology classification criteria and/or revised Chapel Hill 2012 definitions, and their clinical and serological features were evaluated. The association of laboratory data with disease activity was assessed via regression models. Results: Of 219 incident cases of AAV, 37/219 (16.9%) had granulomatosis with polyangiitis (GPA), 172/219 (78.5%) were microscopic polyangiitis (MPA), and 10/219 (4.6%) had eosinophilic granulomatosis with polyangiitis (EGPA). The mean age at diagnosis of patients with GPA were 51.5 years MPA were 61.7 years, and EGPA were 49.8 years, respectively. Patients with MPA were significantly older than GPA and EGPA at diagnosis ( p <0.001). ANCAs tested positive in 207 (94.5%) of cases: 167 (80.7%) were MPO-ANCA and 40 (19.3%) were PR3-ANCA. Lung, skin, nervous system symptoms were the most common in EGPA. For GPA, ear–nose–throat (ENT) symptoms and lungs involvement were the most common. Renal and lung involvement occurs most frequently in MPA. In the multivariable logistic regression analysis, higher anti-MPO antibody (149.4 IU/ml), higher hypersensitive c-reactive protein (hs-CRP, 62.5 mg/L), lower hemoglobin (113.5g/L), and higher complement 4 (C4, >0.215 g/L) were proved to be independent risk factors for active disease. Further research showed that C4 had higher sensitivity (70.0%) and specificity (83.4%) than the other three indicators. Conclusion: MPO-ANCA-positive MPA is the most common form of AAV in Chinese patients. Serum C4 concentrations at diagnosis might be a useful biomarker of disease activity in AAV. References: [1]Jennette JC, Falk RJ, Bacon PA, Basu N, Cid MC, Ferrario F, et al. 2012 revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides. Arthritis Rheum 2013, 65:1-11. [2]Choi H, Kim Y, Jung SM, Song JJ, Park Y-B, Lee S-W. Low serum complement 3 level is associated with severe ANCA-associated vasculitis at diagnosis. Clinical and Experimental Nephrology 2018, 23:223-230. [3]Leavitt RY, Fauci AS, Bloch DA, Michel BA, Hunder GG, Arend WP, et al. The American College of Rheumatology 1990 criteria for the classification of Wegener’s granulomatosis. Arthritis Rheum 1990, 33:1101-1107. [4]Masi AT, Hunder GG, Lie JT, Michel BA, Bloch DA, Arend WP, et al. The American College of Rheumatology 1990 criteria for the classification of Churg-Strauss syndrome (allergic granulomatosis and angiitis). Arthritis Rheum 1990, 33:1094-1100. [5]Mukhtyar C, Lee R, Brown D, Carruthers D, Dasgupta B, Dubey S, et al. Modification and validation of the Birmingham Vasculitis Activity Score (version 3). Ann Rheum Dis 2009, 68:1827-1832. [6]Markiewski MM, Lambris JD. The role of complement in inflammatory diseases from behind the scenes into the spotlight. Am J Pathol 2007, 171:715-727. Disclosure of Interests: None declared