275. Maintenance of Remission and Risk of Relapse in Myeloperoxidase Positive Antineutrophil Cytoplasmic Antibody-Associated Vasculitis Glomerulonephritis

Background: Optimal time of remission-maintenance therapy in patients with MPO-ANCA associated vasculitis (MPO-AAV) is not established. Defining clinical and laboratory parameters to guide safe withdrawal of maintenance therapy is required to mitigate the risk of relapse and unnecessary exposure to immunosuppression. Methods: A retrospective cohort study of all patients followed at the Mayo Clinic with MPO-AAV (MPA and GPA) and glomerulonephritis (MPO-AAV-GN). Relapse rate, correlation with MPO-ANCA status and remission-maintenance therapies were characterized. Results: We analyzed 159 patients with active MPO-ANCA-GN. A total of 66 (41.5%) patients had at least 1 relapse. Patients with MPO-ANCA who became persistently negative did not relapse (HR 0.028, [95%CI,0.003–0.272], p=0.002). The reappearance of MPO-ANCA in patients who had turned MPO-ANCA negative was associated with increased risk of relapse (HR 2.386, [95%CI,1.471–3.870], p<0.0001). Immunosuppression was withdrawn in 80 (50.3%) patients; this was less likely to occur in those who received CYC for remission-induction or were persistently MPO-ANCA positive (OR 0.443, [95%CI,0.228–0.861], p=0.016; OR 0.418, [95%CI,0.213–0.820], p=0.011, respectively). Relapse incidence was not different between patients who withdrew remission-maintenance therapy versus those who maintained (40.0% vs. 43.0%, p=0.697), even in persistently MPO-ANCA positive (39.1% vs. 48.8%, p=0.508). ENT involvement (OR 6.095 [95%CI, 1.280–29.010], p=0.023) and MPO-ANCA reappearance (OR 9.248, [95%CI, 3.126–27.361], p