title: Prognostic Value of Histologic Classification of ANCA-Associated Glomerulonephritis.
abstract: A kidney biopsy is preferred for the diagnosis of ANCA-associated vasculitis with renal involvement. The aim of our study was to evaluate the prognostic value of a histopathologic classification scheme recently proposed by an international consortium of renal pathologists in a large Norwegian cohort.
  
  
  
  Patients diagnosed with ANCA-associated GN were included from the Norwegian Kidney Biopsy Registry 1991-2012. Renal morphology was classified as focal, mixed, crescentic, or sclerotic. Study end point was ESRD. Patients were followed from kidney biopsy to end of 2012.
  
  
  
  Two hundred fifty patients with ≥10 glomeruli in the biopsy were included in our study. During a median follow-up of 3.5 years (0.7-7.6), 60 cases of ESRD occurred. Ninety-six (38%) biopsies were classified as focal, 61 (24%) biopsies were classified as mixed, 71 (28%) biopsies were classified as crescentic, and 22 (9%) biopsies were classified as sclerotic; 1- and 5-year cumulative renal survival rates were 96% and 90%, respectively, for the focal class, 86% and 75%, respectively, for the mixed class, 81% and 69%, respectively, for the crescentic class, and 56% and 51%, respectively, for the sclerotic class. By multivariate Cox regression analyses, the sclerotic class had a significantly worse renal prognosis than the focal (hazard ratio, 9.65; 95% confidence interval, 2.38 to 39.16) or combined mixed/crescentic classes (hazard ratio, 3.27; 95% confidence interval, 1.41 to 7.61), but no significant differences in outcome were observed in the crescentic class compared with the mixed class (hazard ratio, 1.13; 95% confidence interval, 0.44 to 2.87) or the combined mixed/crescentic class compared with the focal class (hazard ratio, 1.93; 95% confidence interval, 0.61 to 6.12). Accuracy by receiver operator characteristic curve analysis was estimated to be 0.72 (95% confidence interval, 0.65 to 0.80). In 108 additional patients with three to nine glomeruli in the biopsy, the prognostic value of this classification scheme was unchanged.
  
  
  
  The histopathologic classification is a predictor of renal outcome of moderate quality. Merging the mixed and crescentic classes in the future could simplify the scheme.
authors: Department of Clinical Medicine, University of Bergen, Bergen, Norway; and.|Emergency Care Clinic and.
authors: Rune
authors: R
authors: Bjørneklett
authors: Department of Clinical Medicine, University of Bergen, Bergen, Norway; and.
authors: Sanjeevan
authors: S
authors: Sriskandarajah
authors: Department of Clinical Medicine, University of Bergen, Bergen, Norway; and.|Department of Pathology, Haukeland University Hospital, Bergen, Norway.
authors: Leif
authors: L
authors: Bostad
mesh_terms: D000328:Adult; D000368:Aged; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000150:complications*; D001706:Biopsy; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D005921:Glomerulonephritis / Q000145:classification / Q000209:etiology* / Q000473:pathology*; D006801:Humans; D007668:Kidney / Q000473:pathology*; D007676:Kidney Failure, Chronic / Q000209:etiology* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009664:Norway; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012372:ROC Curve; D012042:Registries; D015996:Survival Rate
keywords: ANCA; Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis; Antibodies, Antineutrophil Cytoplasmic; Biopsy; Follow-Up Studies; Humans; Kidney Failure, Chronic; Kidney Glomerulus; Prognosis; ROC Curve; Registries; Regression Analysis; classification; glomerulonephritis; kidney; renal pathology; vasculitis