Plasma Exchange for Renal Vasculitis

Inclusion Criteria: * Diagnosis of Wegener's granulomatosis or microscopic polyangiitis, using criteria adapted by EUVAS from the disease definitions of the Chapel Hill consensus conference * Biopsy proven, pauci-immune, necrotising and/or crescentic glomerulonephritis, in the absence of other defined glomerulopathy * Severe renal impairment defined by: (i) oliguria (\<400ml/24hr), or (ii) intention to commence dialysis within 48 hours of admission, and (iii) creatinine \>500umol/l (5.8mg/dl). Exclusion Criteria: * Age under 18 or over 80 years * Inadequate contraception in women of child-bearing age * Pregnancy * Previous malignancy * Hepatitis B antigenaemia, anti-hepatitis C virus or anti-human immunodeficiency virus antibody * Diagnosis of Churg-Strauss syndrome, Henoch-Schönlein purpura, rheumatoid vasculitis, mixed essential cryoglobulinaemia or systemic lupus erythematosus * Circulating anti-GBM antibodies or linear IgG staining of the GBM on renal biopsy * Life-threatening non-renal manifestations of vasculitis, including alveolar hemorrhage requiring mechanical ventilation within 24 hours of admission * On dialysis for \> two weeks prior to entry * Creatinine \> 200umol/l (2.3mg/dl) one year or more before entry * A second clearly defined cause of renal failure * Previous episode of biopsy-proven necrotising and/or crescentic glomerulonephritis * \> two weeks treatment with cyclophosphamide or azathioprine * \> 500mg IV methyl prednisolone * Plasma exchange within…