Histopathological classification of anti-neutrophil cytoplasmic antibody-associated glomerulonephritis in a nationwide Japanese prospective 2-year follow-up cohort study

BackgroundThe prognostic value of the EUVAS-proposed histopathological classification of anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis has been evaluated throughout the world. Here, we performed a Japanese nationwide biopsy survey to assess the association between this histopathological classification and renal prognosis after 2-year follow-up in ANCA-associated glomerulonephritis.MethodsWe collected 67 renal biopsy materials of the 321 entries in the RemIT-JAV-RPGN cohort study, and assessed their histologies. Based on the EUVAS-proposed histopathological classification and some histological parameters, we statistically evaluated renal survival and the comparison of renal function for 2years.ResultsBased on the histopathological classification, the largest number of biopsy samples belonged to the Focal class, followed by the Mixed, Crescentic, and Sclerotic classes (n=30, 19, 10, 8, respectively). Although the number of events might be too low (four patients with renal death) to make this conclusion, the Focal and Mixed classes had higher renal-survival rates compared to the others in the renal-survival curve. Comparing renal function among all classes, the estimated glomerular filtration rate (eGFR) throughout 2-year follow-up period was significantly higher in the Focal class compared to the other 3 classes. The eGFR-values in the Crescentic, Mixed, and Sclerotic classes increased with time. Based on both combined results, the Focal class could be the best prognosis.ConclusionThis histopathological classification was valuable for both the stratification of renal function and the estimation of partial renal survival during 2-year follow-up in ANCA-associated glomerulonephritis.