The Prevalence and Management of Pauci-Immune Glomerulonephritis and Vasculitis in Western Countries

Background: Pauci-immune glomerulonephritis is the most common cause of aggressive glomerulonephritis and occurs as a renal-limited disease or as a component of systemic necrotizing small-vessel vasculitis. It is characterized by paucity of staining for immunoglobulins, by immunofluorescence along with fibrinoid necrosis and crescent formation by light microscopy, while the vast majority of patients have anti-neutrophil cytoplasmic antibodies (ANCA) in their circulation, which also participate in the pathogenesis of the disease.

Summary: Pauci-immune glomerulonephritis often manifests with rapidly deteriorating kidney function, which may be accompanied by distinctive clinical features of systemic necrotizing small-vessel vasculitis of one the following clinical phenotypes: microscopic polyangiitis, granulomatosis with polyangiitis or eosinophilic granulomatosis with polyangiitis. These are associated with a wide spectrum of vasculitic manifestations in different organ systems at clinical presentation and during the course of the disease. ANCA specificity is associated with distinct clinical syndromes and different prognostic profiles among patients. The key element of the management of patients with pauci-immune glomerulonephritis, with or without systemic vasculitis, is the clinical acumen, which results in timely diagnosis. Speed in diagnosis is crucial for the quick institution of immunosuppressive therapy aimed at removing circulating autoantibodies and quelling the inflammatory process.

Key messages: The introduction of ANCA testing in routine clinical practice has increased the ability of disease suspicion and recognition, resulting in earlier establishment of diagnosis by seeking a tissue confirmation of pauci-immune vasculitis. ANCA specificity is associated with distinct clinical syndromes and different prognostic profiles among patients. The management of patients with ANCA glomerulonephritis and/or vasculitis includes two major elements: prompt diagnosis and institution of immunosuppressive therapy to avoid irreversible kidney damage or death, and consideration of the predictors, which are associated with relapsing disease for planning of therapy in the long term.

Facts from east and west: Treatment options for ANCA-associated vasculitis are shared between the East and West, with corticosteroid combined with cyclophosphamide being the standard regimen for inductive therapy and switching to azathioprine after remission. The major cause of death in treated patients is infection related to immunosuppressive therapy within the first year after diagnosis, and this rate might be higher in China than in Western countries. Western studies demonstrated the efficacy and safety of rituximab for induction of remission in cases with relatively mild disease and maintenance therapy, but this agent is rarely used in China.