Plasma Exchange and Glucocorticoids for Treatment of Anti-Neutrophil Cytoplasm Antibody (ANCA) - Associated Vasculitis

Inclusion Criteria: • New or previous clinical diagnosis of granulomatosis with polyangiitis or microscopic polyangiitis consistent with the Chapel-Hill consensus definitions AND • Positive test for proteinase 3-ANCA or myeloperoxidase-ANCA AND * Severe vasculitis defined by at least one of the following: 1. Renal involvement characterized by both of the following: * Renal biopsy demonstrating focal necrotizing glomerulonephritis or active urine sediment characterized by glomerular haematuria or red cell casts and proteinuria AND * eGFR \<50 ml/min/1.73 m2 2. Pulmonary hemorrhage due to active vasculitis defined by: * A compatible chest x-ray or CT scan (diffuse pulmonary infiltrates) AND * The absence of an alternative explanation for all pulmonary infiltrates (e.g. volume overload or pulmonary infection) AND 3. At least one of the following: * Evidence of alveolar hemorrhage on bronchoscopic examination or increasingly bloody returns with bronchoalveolar lavage * Observed hemoptysis * Unexplained anemia (\<10 g/dL) or documented drop in hemoglobin \>1 g/dL) * Increased diffusing capacity of carbon dioxide * Provision of informed consent by patient or a surrogate decision maker Exclusion Criteria: * A diagnosis of vasculitis other than granulomatosis with polyangiitis or microscopic polyangiitis * Positive serum anti-glomerular basement membrane antibody test or renal biopsy demonstrating linear glomerular immunoglobulin deposition * Receipt of dialysis for \>21 days immediately prior to randomization or prior renal transplant * Age \<15 years * Pregnancy at time of study entry * Treatment with \>1 IV dose of cyclophosphamide and/or \>14 days of oral cyclophosphamide and/or \>14 days of prednisone/prednisolone (\>30 mg/day) and/or \>1 dose of rituximab within the 28 days immediately prior to randomization * A comorbidity that, in the opinion of the investigator, precludes the use of cyclophosphamide, glucocorticoids, or plasma exchange or absolutely mandates the use of plasma exchange * Plasma exchange in 3 months prior to randomization