[1621] A Proposed Pathologic Classification System for ANCA-Associated Glomerulonephritis Is Not Effective in Patients with Estimated Glomerular Filtration Rate of <15 at Presentation

Adil H Gasim, Taewoo Lee, Alice S Wilkman, Ronald J Falk, Patrick H Nachman, J Charles Jennette. UNC School of Medicine, Chapel Hill, NC

Background: A classification system has been proposed for glomerulonephritis associate with anti-neutrophil cytoplasmic autoantibodies (ANCA-GN) (Berden at al. J Am Soc Nephrol 21:1628-36, 2010), based on ≥50% sclerotic glomeruli (Sclerotic), ≥50% normal glomeruli (Focal), ≥50% crescents (Crescentic) or none of these (Mixed). We evaluate the effectiveness of this classification in a cohort of patients with very severe disease.
Design: Clinical and pathologic features were evaluated in 115 patients with ANCA-GN and estimated GFR <15ml/min/m2 at presentation; and correlated with outcome. Pathologic evaluation included classification by the Berden system based on % sclerotic glomeruli, % normal glomeruli and % crescents; and semi-quantitative scoring of the pathologic features in Tables 1 and 2 (0-4+ scale). The primary outcome was death or dialysis within 12 months.
Results: The classes were no different in age, sex or presenting eGFR. There was no significant difference (p=0.3) in % of patients reaching ESRD after 12 mo. Pathologic analysis showed that, in these patients with severe clinical disease, all classes had similar degrees of substantial tubulointerstitial injury reflected in the chronicity index (p=0.2) (Table 1) as well as specific tubulointerstitial scores (Table 2). However, the activity index did vary among the classes (p<0.001).

Table 1
Class:n:Activity IndexChronicity Index% ESRD after 12 mo
Focal73.9±1.74.3±3.728.6%
Mixed355.1±1.85.7±2.542.9%
Crescentic518.7±2.66.6±3.556.9%
Sclerotic226.6±3.56.8±3.745.5%
p p<0.01p=0.2p=0.3




Table 2
Class:% Nornal Glomeruli% Crescents% Global SclerosisGlomerular NecrosisInterstitial LeukocytesInterstitial FibrosisTubular Atrophy
Focal62%27%9%0.9+1.0+1.4+1.4+
Mixed20%26%19%1.0+1.4+1.8+1.8+
Crescentic13%75%16%1.9+2.0+2.0+2.1+
Sclerotic6%53%65%1.4+1.7+2.0+2.1+
ANCA:       
MPO-ANCA18%53%26%1.5+1.6+1.9+1.9+
PR3-ANCA15%52%24%1.4+1.8+1.8+1.9+



Conclusions: Pathologic classification of ANCA-GN that is effective in predicting outcomes in patients with a broader range of clinical presentations may not be as effective in patients who present with very severe impairment of GFR. The comparable tubulointerstitial injury indicated that all had sustained substantial renal impairment even though they has different classes of glomerular injury.
Category: Kidney (does not include tumors)

Tuesday, March 5, 2013 8:45 AM

Proffered Papers: Section H, Tuesday Morning

 

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