Abstract
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 < 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.
Highlights
ANCA-associated vasculitis (AAV) poses a significant risk of kidney failure; frequency of kidney involvement in AAV varies from 90% in Microscopic Polyangiitis (MPA) and 80% in Granulomatosis with Polyangiitis (GPA) to 45% in Eosinophilic Granulomatosis with Polyangiitis (EGPA) [1,2]
Anti-MPO-ANCA was associated with the higher extent of fibrotic lesions—both glomerulosclerosis and interstitial fibrosis [29,30]. In this retrospective study of AAV kidney outcomes, we aimed to evaluate kidney survival in association with GN class according to Berden’s classification, with the ANCA Renal Risk Score (ARRS) group, and with the ANCA subtypes
Using ARRS parameters, we evaluated the degree of tubular atrophy and interstitial fibrosis (TA/IF) and of glomerular damage separately, and found that the patients with widespread TA/IF reached stage 5 chronic kidney disease (CKD) significantly more often compared to those with mild TA/IF: kidney survival was 49.6% vs. 87.7% for T2 and T0 points, respectively (p = 0.003) (Figure 4)
Summary
ANCA-associated vasculitis (AAV) poses a significant risk of kidney failure; frequency of kidney involvement in AAV varies from 90% in Microscopic Polyangiitis (MPA) and 80% in Granulomatosis with Polyangiitis (GPA) to 45% in Eosinophilic Granulomatosis with Polyangiitis (EGPA) [1,2]. Kidney survival remains one of the most important outcomes in AAV. A systematic review of 44 studies, performed in 2008 by the European Vasculitis Study Group, found valuable data for GPA only, with kidney survival at 93% and 85% for 1 year and 5 years, respectively; the data for MPA and EGPA were scarce. A multicenter study of 144 patients with MPA managed according to the EULAR recommendations [4] showed that stage 5 chronic kidney disease (CKD) developed in 7.6% of patients with median follow-up of 33.5 months [5]. Another study, including 80% of patients with MPA or renal-limited AAV, demonstrated less optimistic results—47% of patients reached stage 5 CKD by the end of the 5-year follow-up period [6]. A study of the Asian population confirmed unfavorable kidney outcomes for MPA—30.1% of patients reached a composite end-point (doubling of serum creatinine or stage 5 CKD)
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