#5127 COMBINED ACTIVITY AND CHRONICITY SCORE FOR PROGNOSTIC ASSESSMENT IN ANCA-ASSOCIATED VASCULITIS WITH GLOMERULONEPHRITIS

Abstract

Abstract Background and Aims Previous studies have shown that chronic changes on kidney biopsy are useful for stratifying the risk of kidney failure in patients with AAV-GN. We aimed to evaluate the impact of inflammatory activity for the prediction of renal outcomes. Method A retrospective cohort study of MPO- or PR3-ANCA positive patients with AAV and active renal disease. Inflammatory activity was assessed by the Activity Index (AI): a ratio between the number of crescents and/or necrosis and the total number of glomeruli (in percent). We calculated the AI score: 0-5 = 0; 6-10 = 1; 11-15 = 2; 16-20 = 3; 21-25 = 4; 26-37.5 = 5; 37.6-50 = 6; 51-65 = 7; 66-80 = 8; 80-90 = 9; 90-100 = 10. Chronicity was evaluated with the Mayo Clinic Chronicity Score (MCCS). For the combined score, we summed the MCCS and the AI. Results Results. We analyzed 326 patients with kidney biopsies available to score. The biopsies had in median (IQR), 13 glomeruli (9-20), 4 crescents (2-6) and an AI of 28.6% (15.3-47.6). The population was classified according with the risk of progression to kidney failure (KF) in 3 classes as (i) low (0-6) – 114 (35.0%), (ii) intermediate (7-11) – 152 (46.6%), and (iii) high (≥12) – 60 (18.4%). Median eGFR at baseline correlated with the overall risk categories: 42.2 vs. 22.1 vs. 13.4 mL/min/1.73 m2, p<0.0001. The proportion of patients with eGFR< 30 mL/min/1.73 m2 was increased in patients classified as high: 88.3% vs. 66.4% vs. 36.0%, p<0.0001. Renal recovery was more frequent in patients at low risk of progression: 87.7% vs. 64.6% vs. 36.6%, p<0.0001, whereas kidney failure at 12 months and dialysis were more frequent in patients at higher risk (36.7% vs. 12.4% vs. 3.8%, p<0.0001; 35.6% vs. 13.0% vs. 2.9%, p<0.0001, respectively). The combination of AI with MCCS independently predicted the risk of KF at 12 months (HR 1.916, 95%CI 1.210 - 3.033, p = 0.006), particularly increased in patients classified as high risk (HR 3.124, 95%CI 1.224 – 7.970, p = 0.017) and in patients with PR3-ANCA (HR 1.896, 95%CI 1.012 - 3.551, p = 0.046) independently of eGFR at AAV-GN diagnosis and adjusted for severity of renal involvement and age. Conclusion The combined assessment of acute inflammatory activity and chronic changes on kidney histology independently predicted renal outcomes in patients with AAV-GN. The impact of the inflammatory activity is cumulative to the chronic changes.