#4803 Anca Renal Risk Score 2023: The Updated and Revised Arrs

Abstract

Background and Aims Reliable prediction tools are needed to improve prognostication and personalisation of treatment in anti-neutrophil cytoplasmic antibody (ANCA) glomerulonephritides (GN). We aimed to validate and update the ANCA Renal Risk Score (ARRS) prediction model. Method The ARRS working group collated a retrospective multicentre international longitudinal cohort from referral centres and registries across the globe to revise the ARRS in a validation and recalibration study. The primary endpoint was end stage kidney disease (ESKD) and patients were censored at last follow-up. Cox proportional hazards models were used to reweight risk factors and develop a modified scoring system. Kaplan-Meier estimates, Harrell's C statistics and calibration plots were used to assess model performance. Results Of a total of 1591 patients, 1439 were included in the final analyses (959 in the development cohort, 52% male, median age 64 years). The ARRS demonstrated a discrimination of C = 0.800, comparable to the original cohort. Updating the model found an additional useful cut-off for kidney function (K), and serum creatinine replaced glomerular filtration rate which provided higher reliability (K0: <250 μmol/l = 0 points, K1: 250-450 μmol/l = 4 points, K2: >450 μmol/l = 11 points). The risk points for the percentage of normal glomeruli (N) and interstitial fibrosis and tubular atrophy (T) were also reweighted (N0: >25% = 0 points, N1: 10-25% = 4, N2: < 10% = 7, T0: none, mild or < 25% = 0 points, T1: ≥ mild-moderate or ≥ 25% = 3 points). We created four risk groups based on the sum of points: low (0 – 4 points), moderate (5 – 11), high (12 – 18) and an additional very high-risk (21). The model discrimination was C = 0.831 and a supplemental continuous model was developed to supply a patient-specific annual risk. Three-year kidney survival was 96%, 79%, 54%, and 19%, respectively. The ARRS23 performed similarly well in the validation cohort with excellent calibration. Conclusion We demonstrated the out-of-sample validity of the ARRS and present here the modified and improved score to optimise prognostication and risk stratification for clinical practice and trials.

ANCA-associated vasculitis—treatment standard

“…The Berden classification includes glomerular lesions (acute/chronic) and defines four classes; focal, mixed, crescentic and sclerotic, and the Mayo Clinic Chronicity score (MCCS) combines only the chronic features from all the renal compartments (glomeruli, interstitial, vessels) and presents four groups of severity. The ANCA Renal Risk Score (ARRS) incorporates both baseline kidney function, and histopathological characteristics (normal glomeruli and tubular atrophy/interstitial fibrosis), to predict the risk of ESKD categorized into three severity groups (recently updated to four groups) [ 50 ]. Although even in cases with the most chronic lesions or the highest risk of ESKD, there is still a chance of renal recovery, these scores cannot determine management decisions.…”