#5346 RE-ASSESSMENT OF PATHOLOGICAL DATA OF VASCULITIS PATIENTS WITH RENAL INVOLVEMENT ACCORDING TO CURRENT SCORING SYSTEMS AND CLINICAL CORRELATION
Authors: Eralp Deniz , Atas Dilek Barutcu , Tugcu Murat , Velioglu Arzu , Arikan Izzet Hakki , Alibaz-Oner Fatma , Direskeneli Haner , Asicioglu Ebru , Tuglular Z Serhan 
Published: June 2023

Abstract

Background and Aims
Renal involvement is responsible for substantial morbidity and mortality in ANCA associated vasculitis (AAV) patients. Predicting renal prognosis in AAV patients with renal involvement has been a challenge over the last decade. To date Berden Classification which focuses on glomerular lesions at renal biopsy proposed in 2010, Mayo Clinic Chronicity Score also including non-glomerular histopathological chronicity findings proposed in 2017 and adding eGFR at diagnosis to glomerular and non-glomerular chronicity findings at renal biopsy constructing ANCA Renal Risk Score (ARRS) proposed in 2018 have all addressed the latter challenge. In this study, we aimed to validate the impact of these 3 classification systems on the renal and patient survival in our ANCA associated glomerulonephritis (AAGN) patient population.

Method
Thirty-seven AAV patients with biopsy proven renal involvement who have been treated and followed-up at our multidisciplinary vasculitis clinic at Marmara University School of Medicine, Istanbul, Turkey between 2000-2020 were included in the study. Renal biopsies were re-evaluated by our pathologist and patients were grouped according to Berden Classification, Mayo Chronicity Score and ARRS. Renal survival and mortality analyses were carried out for 3 classification systems in order to evaluate their success at predicting prognosis and survival.

Results
Evaluated according to Berden Classification, 40.5% (n = 15) were classified as focal, 8.1% (n = 3) were sclerotic, 40.5% (n = 15) were crescentic and 10.8% (n = 4) were mixed. Focal group was associated with best renal prognosis and patients in mixed group had poorest renal prognosis. Differences in renal survival rates (p = 0.111) and patient survival rates (p = 0.129) among Berden Classification groups were not statistically significant. According to Mayo Chronicity Score, 16.2% of the patients were scored as minimal, 51.4% were as mild and %32.4 were in medium group. None of the patients were classified as severe. Compared to minimal group, mild and medium groups were found to be significantly associated with CKD development (p = 0.002). Mortality rates were similar between the groups according to Mayo Chronicity Score (p = 0.143). In renal survival analysis, mild and medium groups were associated with decreased renal survival (p = 0.046). When evaluated for ARRS, 29.4% of the patients were in low risk group, 45.9% of the patients were in medium risk group and 24.3% of the patients were in high risk group. Medium and high risk groups were associated with higher probability of progression to CKD (p = 0.000). Renal survival was found to be poorest in high risk group and best in low risk group (p = 0.017). Although mortality rates were higher in medium risk group than lower and higher risk groups, the difference has not reached statistical significance (0(0%) vs. 7 (38.9%) vs. 2 (22.2%); p = 0.067). Renal survival in AAGN patients according to Berden Classification, Mayo Chronicity Score and ARRS parameters are shown in Figure 1.

Conclusion
Recent classification systems were evaluated among our AAGN patients and our results showed that addition of eGFR at diagnosis to glomerular and non-glomerular histopathological findings were predictive of renal prognosis. Mayo Chronicity Score and ARRS systems can be used to predict patients’ renal reserve at diagnosis and also they can be used as a prognostic tool to predict patients’ probability of progressing to chronic kidney disease, end stage kidney disease.