Clinical characteristics and potential biomarkers for disease activity of patients with ANCA associated vasculitis: a monocenter study in China

Objective: 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 (male/female, 18/19), MPA were 61. 7 years (male/female, 84/88), and EGPA were 49.8 years ( male/female, 7/3), respectively. Patients with MPA were significantly older than GPA and EGPA at diagnosis ( p 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.