Background/Purpose: The aim of this study was to evaluate the predictors of advanced chronic kidney disease (ACKD) in patients with Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis and renal involvement.

Methods: Observational retrospective study. We included all patients with biopsy-proven ANCA glomerulonephritis (GN) diagnosed between 2001 and 2016, with at least one year of follow-up. Data was recorded at diagnosis, end of induction treatment, after one year of treatment, and at the end of follow-up. We analyzed serum creatinine, estimated glomerular filtration rate (eGFR), proteinuria, hematuria, renal histopathology and autoantibodies, as well as received treatments, requirement of dialysis, and renal or extra-renal relapses. Renal biopsies were reviewed and classified in accordance to the 2010 histopathologic classification of ANCA-associated GN. Univariate analysis were performed to identify factors associated with long-term ACKD (eGFR < 30 ml/min, stages 4 or 5 of KDIGO classification). The diagnostic accuracy for ACKD of each predictor variable were compared using areas under the curve (AUC) of ROC (receiver operating characteristic) curves.

Results: Sixty patients with ANCA GN were included: 17 Granulomatosis with polyangiitis (GPA), 14 Microscopic polyangiitis (MPA), 5 Eosinophilic granulomatosis with polyangiitis (EGPA), and 24 Renal-limited vasculitis (RLV). Forty-six patients were women (76.7%), with a mean age of 67.8 years (SD 13.1) at diagnosis. Median follow-up time was 4.2 years (IQR 2.2-6.8). The most frequently found histopathologic class was the focal class (20 patients, 33.3%), followed by mixed (17 patients, 28.3%), crescentic (16 patients, 26.7%), and sclerotic class (7 patients, 11.7%). Regarding treatment, 53 patients (88.3%) received cyclophosphamide, 42 (70%) IV pulse steroid therapy, 11 (18.3%) plasmapheresis and 10 (16.7%) transient dialysis. Seventeen patients (28.8%) needed to be re-biopsied during follow-up, and renal relapse was confirmed on 14 (26.4%) of them. Additionally, 11 patients (19.6%) had an extra-renal relapse. Four patients (6.7%) remained on permanent dialysis. At the end of follow-up, 12 patients (20.7%, 95% CI 11.9-33.4%) had an eGFR < 30 ml/min (Table 1). The univariate analysis showed a statistically significant association of ACKD with the sclerotic class biopsy (OR 7.17, 95% CI 1.34-38.31, p 0.02), and serum creatinine at diagnosis (OR 1.24, 95% CI 1.02-1.52, p 0.03), end of induction (OR 15.4, 95% CI 2.41-98.28, p 0.004), and after 12 months (OR 19.25, CI 95% 2.75-134.92, p 0.003). We found no significant association of ACKD with proteinuria, hematuria, ANCA positivity at different times nor any other of the analyzed variables (Table 2). The best diagnostic accuracy in ROC curves was shown by serum creatinine at the end of induction (AUC 0.93, 95% CI 0.83-1.00) and at 12 months (AUC 0.94, 95% CI 0.85-1.00) (Figure 1).

Conclusion: In this cohort of patients with ANCA vasculitis and renal involvement, serum creatinine at the end of induction and after 12 months of treatment were the best predictors of ACKD (eGFR < 30ml/min) at the end of follow-up.

Table 1

Table 2

Figure 1

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/predictors-of-advanced-chronic-kidney-disease-in-patients-with-anca-vasculitis-and-renal-involvement/