Developments in the Histopathological Classification of ANCA-Associated Glomerulonephritis
Clinical Journal of the American Society of Nephrology, vol. 15, pp. 1103–1111
Abstract
Background and objectives The histopathologic classification for ANCA-associated GN distinguishes four classes on the basis of patterns of injury. In the original validation study, these classes were ordered by severity of kidney function loss as follows: focal, crescentic, mixed, and sclerotic. Subsequent validation studies disagreed on outcomes in the crescentic and mixed classes. This study, driven by the original investigators, provides several analyses in order to determine the current position of the histopathologic classification of ANCA-associated GN. Design, setting, participants, & measurements A validation study was performed with newly collected data from 145 patients from ten centers worldwide, including an analysis of interobserver agreement on the histopathologic evaluation of the kidney biopsies. This study also included a meta-analysis on previous validation studies and a validation of the recently proposed ANCA kidney risk score. Results The validation study showed that kidney failure at 10-year follow-up was significantly different between the histopathologic classes ( P <0.001). Kidney failure at 10-year follow-up was 14% in the crescentic class versus 20% in the mixed class ( P =0.98). In the meta-analysis, no significant difference in kidney failure was also observed when crescentic class was compared with mixed class (relative risk, 1.15; 95% confidence interval, 0.94 to 1.41). When we applied the ANCA kidney risk score to our cohort, kidney survival at 3 years was 100%, 96%, and 77% in the low-, medium-, and high-risk groups, respectively ( P <0.001). These survival percentages are higher compared with the percentages in the original study. Conclusions The crescentic and mixed classes seem to have a similar prognosis, also after adjusting for differences in patient populations, treatment, and interobserver agreement. However, at this stage, we are not inclined to merge the crescentic and mixed classes because the reported confidence intervals do not exclude important differences in prognosis and because an important histopathologic distinction would be lost.
Authors 29
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Leiden University Medical Center
Affiliation as printed
Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
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Leiden University Medical Center
Affiliation as printed
Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
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Azienda Ospedaliera San Gerardo
Affiliation as printed
Nephropathology Center, San Gerardo Hospital, Monza, Italy
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Jikei University School of Medicine
Affiliation as printed
Department of Pathology, The Jikei University School of Medicine, Tokyo, Japan
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Hôpital Necker-Enfants Malades · Université Paris Descartes
Affiliation as printed
Department of Pathology, Necker Hospital, René Descartes University, Paris, France
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Affiliation as printed
Hokkaido Renal Pathology Center, Sapporo, Japan
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Affiliation as printed
Pathology Laboratory Pathan, Rotterdam, The Netherlands
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Affiliation as printed
Clinical Institute of Pathology, Medical University of Vienna, Vienna, Austria
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Institute of Clinical and Experimental Medicine
Affiliation as printed
Department of Pathology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic
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Charles University · General University Hospital in Prague
Affiliation as printed
Department of Nephrology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
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Affiliation as printed
Clinical Institute of Pathology, Medical University of Vienna, Vienna, Austria
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Japan Community Healthcare Organization · Sendai Shakai Hoken Hospital
Affiliation as printed
Department of Nephrology, Japan Community Healthcare Organization, Sendai Hospital, Sendai, Japan
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Institute of Clinical and Experimental Medicine
Affiliation as printed
Department of Pathology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic
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Innsbruck Medical University · Universität Innsbruck
Affiliation as printed
Department of Internal Medicine IV (Nephrology and Hypertension), Medical University Innsbruck, Innsbruck, Austria
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University of Copenhagen · Rigshospitalet
Affiliation as printed
Department of Nephrology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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Hôpital Cochin · Assistance Publique – Hôpitaux de Paris
Affiliation as printed
Department of Internal Medicine, National Referral Center for Rare Autoimmune and Systemic Diseases, Hôpital Cochin, Assistance Publique-Hôpitaux de Paris, Paris, France
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Affiliation as printed
Department of Pathology, Weill Cornell Medical College, New York, New York
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University of Copenhagen · Rigshospitalet
Affiliation as printed
Department of Nephrology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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Affiliation as printed
Department of Nephrology, Teine Keijinkai Hospital, Sapporo, Japan
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Charles University · General University Hospital in Prague
Affiliation as printed
Department of Nephrology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
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Annelies E. Berden Aachen Department of Pathology, Leiden University Medical Center Department of Rheumatology, Leiden University Medical Center
Leiden University Medical Center
Affiliation as printed
Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
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Leiden University Medical Center
Affiliation as printed
Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands
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Affiliation as printed
Department of Nephrology, Meander Medical Center, Amersfoort, The Netherlands
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Leiden University Medical Center
Affiliation as printed
Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
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Leiden University Medical Center
Affiliation as printed
Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
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Leiden University Medical Center
Affiliation as printed
Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden, The Netherlands
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Leiden University Medical Center · St. Antonius Ziekenhuis
Affiliation as printed
Department of Internal Medicine, St. Antoniusziekenhuis, Nieuwegein, The Netherlands
Department of Nephrology, Leiden University Medical Center, Leiden, The Netherlands
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Leiden University Medical Center
Affiliation as printed
Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
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Leiden University Medical Center
Affiliation as printed
Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
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