P2_81 MPO-ANCA is a Promising Biomarker for Relapse in Renal Vasculitis; Subgroup Analysis of Nationwide Prospective Cohort Study of ANCA-Associated Vasculitis and Rapidly Progressive Glomerulonephritis (RemIT-JAV-RPGN)

Abstract

Objectives: Several studies reported that an increase levels of antineutrophil cytoplasmic antibody (ANCA) might predict relapse in patients with ANCA-associated vasculitis (AAV) but still controversial. The aim of this study was to evaluate transition of myeloperoxidase (MPO)-ANCA related to clinical characterstics and relapse using data set from nationwide prospective cohort study of remission induction therapy in Japanese patients with AAV and rapidly progressive glomerulonephritis (RemIT-JAV-RPGN). Methods: MPO-ANCA positive patients who achieved remission by 6 months were enrolled. MPO-ANCA was repeatedly measured at baseline, 3, 6, 12, 18 and 24 months. First, the enrolled patients were divided into two categories according to MPO-ANCA transition within 6 months; persistently positive or negative conversion. Subsequently, the patients with MPO-ANCA negative conversion were divided into two subgroups; positive conversion or persistently negative. The primary outcome was relapse. Results: Two hundreds fifteen patients were included in this analysis; 144 with microscopic polyangiitis, 28 with granulomatosis with polyangiitis and 11 with eosinophilic granulomatosis with polyangiitis. The average age of the patients was 70.6 years and 123 (57%) were female. MPO-ANCA converted to negative within 6 months in 156 patients (73%) and the positivity persisted in 59 patients (27%). The patients with negative conversion of MPO-ANCA had more severe Japanese RPGN clinical grading and exhibited higher mortality rate compared to those with persistently positive (grade III and IV: 28.2% vs. 13.6%, p<0.05; mortality: 6.4% vs. 0%, p<0.05, respectively). Of 156 patients with negative conversion of MPO-ANCA, 46 (29%) patients exhibited positive conversion while 110 (71%) patients were persistently negative for MPO-ANCA during observational periods but the relapse rate was comparable (19.6% vs. 11.8%, p=0.20). Of 129 patients with renal involvement and MPO-ANCA negative conversion within 6 months, the patients with MPO-ANCA positive conversion developed relapse more frequently than those with persistently negative but not significant (22.5% vs. 12.4%, p=0.14). If limiting 84 patients with RPGN, the relapse was significantly more frequent in patients with MPO-ANCA positive conversion than those with persistently negative (30.8% vs. 10.3%, p<0.05). Conclusions: The conversion of MPO-ANCA from negative to positive related to relapse in RPGN patients.