This study found that incidence rates of primary GN vary between 0.2/100,000/year and 2.5/100,000/year. The incidence of IgA nephropathy is at least 2.5/100,000/year in adults; this disease can exist subclinically and is therefore only detected by chance in some patients. In addition, referral policies for diagnostic biopsy vary between countries. This will affect the incidence rates found.

Significant advances have lead to a greater understanding of the role of the complement system within nephrology. The success of the first clinically approved complement inhibitor has created renewed appreciation of complement-targeting therapeutics. Several clinical trials are currently underway to evaluate the therapeutic potential of complement inhibition in renal diseases and kidney transplantation. Although, complement has been known to be activated during dialysis for over four decades, this area of research has been neglected in recent years. Despite significant progress in biocompatibility of hemodialysis (HD) membranes and peritoneal dialysis (PD) fluids, complement activation remains an undesired effect and relevant issue. Short-term effects of complement activation include promoting inflammation and coagulation. In addition, long-term complications of dialysis, such as infection, fibrosis and cardiovascular events, are linked to the complement system. These results suggest that interventions targeting the complement system in dialysis could improve biocompatibility, dialysis efficacy, and long-term outcome. Combined with the clinical availability to safely target complement in patients, the question is not if we should inhibit complement in dialysis, but when and how. The purpose of this review is to summarize previous findings and provide a comprehensive overview of the role of the complement system in both HD and PD.

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Franssen C, Gans R, Kallenberg C, Hageluken C, Hoorntje S (University Hospital, Groningen; Free University Hospital, Amsterdam; and Catharina Hospital, Eindhoven; the Netherlands). Disease spectrum of patients with antineutrophil cytoplasmic autoantibodies of defined specificity: distinct differences between patients with antiproteinase 3 and antimyeloperoxidase autoantibodies. J Intern Med 1998; 244: 209–16. Objective To compare the disease spectrum of consecutive patients with antineutrophil cytoplasmic autoantibodies directed against proteinase 3 (anti‐PR3) or myeloperoxidase (anti‐MPO). Design Retrospective analysis. Setting Three teaching hospitals in the Netherlands. Main outcome measures Clinical features at presentation, histopathological characteristics and outcome. Subjects All consecutive patients who tested positive for anti‐PR3 (n= 46) or anti‐MPO (n= 46) over an 8‐year‐period. Results At diagnosis, patients with anti‐PR3 had a higher vasculitis activity index than patients with anti‐MPO (P < 0.001). The mean (SD) number of affected organs in the anti‐PR3 group exceeded that of the anti‐MPO group (3.9 (1.4) and 2.2 (1.1), respectively; P < 0.01). The combination of renal and respiratory tract involvement was present in as many as 78.3% of patients with anti‐PR3 and in only 23.9% of patients with anti‐MPO (P < 0.01). Renal‐limited disease exclusively occurred in patients with anti‐MPO. Granulomas were found in 41.3% of anti‐PR3‐ but in only 4.3% of anti‐MPO‐positive patients (P < 0.01). All anti‐PR3‐positive patients had Wegener's granulomatosis or microscopic polyangiitis. By contrast, diagnoses in the anti‐MPO group were more diverse: idiopathic necrotizing crescentic glomerulonephritis (26.1%), microscopic polyangiitis (26.1%), Churg–Strauss syndrome (4.3%), Wegener's granulomatosis (2.2%), giant cell arteritis (2.2%), clinically suspected vasculitis (19.6%), as well as miscellaneous nonvasculitic disorders (19.6%). During follow‐up, 10 anti‐PR3‐positive patients had 11 relapses whereas only 3 patients with anti‐MPO relapsed (P= 0.04). Conclusion A large divergence was seen in the disease spectrum between patients with anti‐PR3 and those with anti‐MPO. In particular, extra‐renal disease manifestations, granuloma formation and relapses were more prominent in anti‐PR3‐ than in anti‐MPO‐positive patients.