Evaluating renal outcome of ANCA-associated renal vasculitis: comparative study of two histopathological scoring systems

Objective. Renal risk score (RRS) and chronicity score (CS) are both newly proposed tools to predict end stage renal disease (ESRD) which could be applicable in antineutrophil cytoplasmic antibody (ANCA)-associated renal vasculitis patients. Their predictive value has not been fully studied and compared. Method. 252 patients with newly biopsy-proven ANCA-associated renal vasculitis were retrospectively studied at the Department of Nephrology, Ruijin Hospital, China. Patients were evaluated with RRS and CS for clinical factors, pathological lesions and outcome. Their predictive value of renal survival was also compared. Result. The median RRS score point at diagnosis was 6 (interquartile range [IQR] 0-9) and CS score point was 4 (IQR 3-7). In accordance with severity of RRS category and CS grade, percentage of hypertensive patients, dialysis dependency, and level of proteinuria increased accordingly. Significant differences were found regarding dialysis dependency within RRS and CS groups (p<0.001 and p<0.01 respectively). The addition of RRS or CS scoring scheme to the base model of dialysis dependency significantly improved discrimination. The C statistic, integrated discrimination improvement and net reclassification improvement were significantly increased by adding either RRS/CS or both. Furthermore, RRS had better ROC. Conclusion. Among ANCA-associated renal vasculitis patients, RRS and CS achieved similar discrimination, but the discrimination of RRS was superior.