Adding 6-month parameters for the prediction of kidney prognosis in ANCA-associated glomerulonephritis

Background. Antineutrophil-cytoplasmic antibody (ANCA)-associated vasculitis (AAV) with kidney involvement (AAV-GN) frequently evolves to end-stage kidney disease (ESKD) despite aggressive immunosuppressive treatment. Several risk scores have been used to assess renal prognosis. We aimed to determine whether kidney function and markers of AAV-GN activity after 6 months could improve the prediction of ESKD. Methods. This retrospective and observational study included adult patients with AAV-GN recruited from six French nephrology centers (including from the Maine-Anjou AAV registry). The primary outcome was kidney survival. Analyses were conducted in the whole population and in a sub-population that did not develop ESKD early in the course of the disease. Results. When considering the 102 patients with all data available at diagnosis, Berden classification and Renal Risk Score (RRS) were not found to be better than kidney function [estimated glomerular filtration rate (eGFR)] alone at predicting ESKD (C-index = 0.70, 0.79, 0.82, respectively). Multivariables models did not indicate an improved prognostic value when compared with eGFR alone. When considering the 93 patients with all data available at 6 months, eGFR outperformed Berden classification and RRS (C-index = 0.88, 0.62, 0.69, respectively) to predict ESKD. RRS performed better when it was updated with the eGFR at 6 months instead of the baseline eGFR. While 6-month proteinuria was associated with ESKD and improved ESKD prediction, hematuria and serological remission did not. Conclusion. This work suggests the benefit of the reassessment of the kidney prognosis 6 months after AAV-GN diagnosis. Kidney function at this time remains the most reliable for predicting kidney outcome. Of the markers tested, persistent proteinuria at 6 months was the only one to slightly improve the prediction of ESKD. [GRAPHICS] .