Kidney Pathology and Outcomes in ANCA-Associated Vasculitis: Retrospective Analysis of 85 Patients

ANCA-associated vasculitis (AAV) poses a significant risk of kidney failure
kidney biopsy remains a key prognostic tool. The histopathologic classification of AAV glomerulonephritis (GN) developed by Berden et al. showed correlation between GN classes and kidney outcomes
ANCA Renal Risk Score (ARRS) included tubular atrophy and interstitial fibrosis (TA/IF) as an additional parameter for risk assessment. We aimed to evaluate kidney survival across AAV GN classes and ARRS groups. A single-center retrospective study included 85 adult patients with biopsy-proven AAV kidney disease followed in the period of 2000–2020. Primary outcome was kidney survival at the end of 18 (5
66) months follow-up, and kidney death was considered as stage 5 CKD. We found significant differences in kidney survival for sclerotic, mixed, crescentic and focal AAV GN classes: 19%, 76.2%, 91.7% and 100%, respectively (p = 0.009). Kidney survival was 0%, 75.6% and 100% for the high-, medium- and low-risk ARRS groups, respectively (p &lt
0.001)
TA/IF analysis showed kidney survival at 49.6% vs. 87.7% for widespread and mild TA/IF, respectively (p = 0.003). Kidney survival was significantly lower in anti-MPO-ANCA versus anti-PR3-ANCA carriers (50.3% and 78.1%, respectively, p = 0.045). We conclude that unfavorable AAV kidney outcomes are associated with sclerotic GN class by Berden’s classification, ARRS high risk group, and anti-MPO-ANCA subtype.