Shifting Sands or ANCA-ed in Place? The Epidemiology of ANCA-Associated Vasculitis over 2 Decades at a Large Tertiary Centre.

Introduction: Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a systemic condition usually affecting small blood vessels, commonly causing kidney disease. It has a reported incidence of around 20-25 per million per year. AAV includes both granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). Here, we describe the epidemiology of this condition at our renal centre over a 23-year period, compare GPA and MPA and compare the overall cohort by era of diagnosis. Methods: We identified all patients with AAV with renal involvement between January 2000 and December 2022 through our biopsy database and electronic patient record. The cohort after exclusions totaled 278. We collected demographic data, baseline laboratory values, treatment received and outcomes including progression to renal replacement therapy (RRT), relapse rates and mortality. We performed subgroup analysis comparing those with GPA and MPA, and created 4 groups by era of diagnosis. Results: Median age of the cohort was 63.5 years (interquartile range [IQR] 52-72), 52.5% were male and 92.4% White. GPA was seen in 49.3% and MPA in 42.1%. There was advanced renal disease at presentation with median eGFR 18 mL/min/1.73 m Conclusions: This is one of the largest retrospective observational studies conducted on AAV. We demonstrate that there were more cases of GPA (49.2%) compared to MPA (42.1%) presenting to our centre; comorbidity rates were high; there was advanced renal disease at presentation and mortality rate appeared to improve in the more recent eras.