ANCA associated vasculitis: experience of a tertiary care referral center.

BACKGROUND AND OBJECTIVES: Anti-neutrophil cytoplasmic autoantibodies (ANCA) associated vasculitis is a small vessel vasculitis with insufficient epidemiologic estimates in the United States. We aimed to determine demographic and clinical features of ANCA associated vasculitis patients presenting to a large tertiary care referral center in Upstate New York. Design, setting, participants, and measurements: A retrospective analysis of cases with pauci-immune GN on renal biopsy and clinical diagnosis of ANCA vasculitis presenting over 11 years was conducted. Outcomes of interest were: demographics, ANCA antibody positivity, patient and renal survival, and regional trends.

RESULTS: 986 biopsies were reviewed, 41 cases met the criteria for inclusion: 18 GPA, 19 MPA, and 4 double positive (anti-GBM disease plus ANCA vasculitis). Mean age at presentation was 52.4 years (SD 23.7), 23 (56%) were male and median creatinine was 2.6 mg/dL. The median patient follow up was 77 weeks (IQR 10 - 263 weeks), with a 3-month mortality rate of 5.7% and a 1-year estimated mortality rate of 12%. Thirteen patients required hemodialysis at the time of diagnosis; 7 patients came off dialysis, with median time to renal recovery of 4.86 weeks (IQR 1.57 - 23.85 weeks). C-ANCA positivity (p < 0.001) and C-ANCA plus PR3 antibody pairing (p = 0.005) was statistically significant in GPA versus MPA. P-ANCA positivity was observed in MPA versus GPA (p = 0.02) and double positive versus GPA (p = 0.002), with P-ANCA and MPO antibody pairing in MPA versus GPA (p = 0.044). Thirty-seven of the 41 cases were referred locally, 16 cases were from within a 15-mile radius of Albany, Schenectady, and Saratoga counties.

CONCLUSIONS: ANCA vasculitis is associated with end stage renal disease and increased mortality. Our study suggests the possibility of higher regional incidence of pauci-immune GN in Upstate New York. Further studies should investigate the causes of clustering of cases to specific regions.