Incidence and outcome of pauci-immune rapidly progressive glomerulonephritis in Wessex, UK: a 10-year retrospective study

Background. The Wessex Renal Unit serves a large stable population (2.5 million). Pauci-immune rapidly progressive glomerulonephritis (RPGN) is a frequent cause of acute renal failure requiring admission to our unit (similar to 8%). At a population level, little is known of the epidemiology and outcome of RPGN. Methods. Between 1 April 1986 and 31 March 1996, 141 cases of biopsy proven pauci-immune RPGN were seen in the Wessex region. The records of 128 patients were reviewed. Median (range) follow-up was 1.8 (0.9-9.64) years from diagnosis. Results. The incidence of 4 per million was stable throughout the period. No clustering was seen. The diagnosis was made (median, 25th, 75th centile) 78.5 (45, 166) days after symptom onset. Co-morbidity (mostly hypertension) was seen in 47% of patients. Other organs affected were lungs 63%, nose/sinuses 50%, joints 42%, muscle 33%, skin 22% and nervous system 14%. Anti-neutrophil cytoplasmic antibody (ANCA) was positive in 73%; cytoplasmic ANCA 34%, peri-nuclear ANCA 26% and undifferentiated 14%. Twenty-seven per cent tested ANCA negative. The differences between the groups were small; time to diagnosis was shorter in the ANCA negative (-ve) group (P = 0.02) and there were more airway symptoms in the ANCA positive (+ve) group (P < 0.05). All biopsies demonstrated a necrotizing process; crescents were seen in 96% involving (mean +/- SD) 54 +/- 26% of the glomeruli. Creatinine concentration (mean +/- SD) at diagnosis was 806 +/- 540 mu mol/l. Treatment followed established immunosuppressive regimens. Initial dialysis was required by 59%, 36% needing long-term dialysis. At 1 year 68% were alive. The need for dialysis (P = 0.0003) and age (P = 0.004) were poor prognostic markers. Ten per cent were transplanted, graft survival was 90% at 1 year, no recurrence was seen. Conclusions. This study, looking at a large cohort, has established the incidence and outcome of ANCA +ve and ANCA -ve RPGN in a defined stable population. It stresses the similarities between ANCA +ve and ANCA -ve cases and supports the notion that pauci-immune RPGN is part of a continuum of vasculitic illness. In this series transplantation is a safe option.