Comparison of Clinico-pathologic features and outcomes of ANCA negative and ANCA positive pauci immune crescentic glomerulonephritis: A single centre study

Introduction: Pauci-immune crescentic glomerulonephritis (PICN) is an important cause of rapidly progressive renal failure. 10-40% of PICN cases have ANCA negative serology. Present study compared clinico-pathologic features, Brix’s renal risk score, Berden’s histopathological classes and differences in outcome between ANCA-ve vs ANCA+ve PICN. Methods: 61 patients of biopsy proven PICN were studied. Biochemical finding and ANCA serology were recorded. Renal biopsies slides were reviewed along with direct Immunofluorescence. Clinical and histological features were compared between ANCA negative and positive PICN using Man Whitney U test and chi square test. Patients were compared for distribution in Berden’s histological classes and Brix’s renal risk categories. Patient and renal survival were compared using Kaplan Meier survival analysis. Results: ANCA negative PICN patients were younger ( 44.9±16.5year vs 53.6±15.1 year,p=0.049 ). Nasal( 0 vs 18% , p=0.035 ) and pulmonary involvement( 9% vs 38%,p=0.014 ) were lower in ANCA negative group. Both ANCA groups had similar renal biochemical profile, percentage normal glomeruli, 16.27±18.25vs21.69±20.42 and percentage glomeruli with crescents, 64.45±28.12vs64.25±27.11. 27% ANCA negative cases fell in the sclerotic class in Berden’s classification vs just 2.5% in ANCA positive group( p=0.037 ) without significant difference in Brix’s renal risk categories(p=0.329). 13% of ANCA –ve patients achieved complete remission on treatment compared to 33% in ANCA +ve patients. Patient survival and overall probability of progressing to ESRD were similar in the two groups. Conclusion: ANCA negative PICN cases present at younger age. Nasal and pulmonary involvement is uncommon with fewer cases achieving remission on treatment. Patient survival and progression to ESRD is similar in both ANCA groups.