Incidence, prevalence, mortality and chronic renal damage of anti-neutrophil cytoplasmic antibody–associated glomerulonephritis in a 20-year population-based cohort

Background True population-based clinical and outcomes data are lacking for anti-neutrophil cytoplasmic autoantibody (ANCA)-associated glomerulonephritis (AAGN). Therefore we aimed to estimate the incidence, prevalence and mortality of AAGN, as well as the relationship between the grade of chronic renal damage at presentation and renal and non-renal outcomes. Methods Patients with AAGN were identified among a population-based incident cohort of 57 Olmsted County residents diagnosed with ANCA-associated vasculitis (AAV) in 1996–2015. Incidence rates were age and sex adjusted to the 2010 US white population. Age- and sex-adjusted prevalence was calculated for 1 January 2015. Survival rates were compared with expected rates in the Minnesota population. Chronic renal damage was assessed by chronicity score (CS) on biopsies performed at diagnosis. Results Thirty-four (60%) patients had AAGN. Of these, 65% had microscopic polyangiitis (MPA) and 74% were myeloperoxidase (MPO)-ANCA positive. The annual incidence of AAGN was 2.0/100 000 population [95% confidence interval (CI) 1.3–2.7] and the overall prevalence was 35/100 000 (95% CI 24–47). Mortality for AAGN was increased (P Conclusions The annual incidence and prevalence of AAGN in Minnesota are 2.0/100 000 and 35/100 000, respectively. Mortality is worse compared with AAV patients without glomerulonephritis. More advanced renal damage at diagnosis predicts less renal recovery.