P0386OUTCOMES OF PAUCI-IMMUNE CRESCENTIC GLOMERULONEPHRITIS BASED ON THE INTERNATIONAL HISTOPATHOLOGICAL CLASSIFICATION AND RECENTLY PROPOSED RENAL RISK SCORE IN ADULTS: A SINGLE CENTER STUDY

Abstract

Abstract Background and Aims Pauci-immune crescentic glomerulonephritis is rare form of glomerulonephritis that frequently presents as rapidly progressive renal failure. The histopathological classification proposed by Berden a decade earlier described difference in the outcomes of patients in the focal, crescentic, mixed and sclerotic category with best prognosis for focal and worst for sclerotic group. The newly proposed renal risk score (Brix SR at al.) takes into account both the histopathological parameters (% of normal glomeruli, tubular atrophy and interstitial fibrosis) and clinical parameter (eGFR) which influence outcome in these patients. Present study was undertaken to determine outcomes of pauci-immune crescentic glomerulonephritis based on both of these prognostic systems and also to determine effect of individual risk factors on renal outcome. Method 64 patients diagnosed as pauci-immune crescentic glomerulonephritis from January 2013 to December 2018 were retrospectively analyzed. There histopathological slides were reviewed for percentage normal glomeruli, extent of interstitial fibrosis and tubular atrophy and biopsies were also grouped according to histopathological classification into focal, crescentic, mixed and sclerotic categories. The clinical parameters including serum creatinine, eGFR at time of biopsy and follow-up, and status of ANCA positivity were obtained from electronic records. Renal biopsies were scored based on renal risk score depending on the % of normal glomeruli (>25%,10-25% and <10%), percentage of tubular atrophy and interstitial fibrosis(≤25%,>25%) and eGFR(>15ml/min,≤15ml/min) into 3 risk categories. Results There were 61 adult patients and 3 pediatric patients. Two patient with insufficient glomeruli (<7) on biopsy and 8 patients without follow-up were excluded. A total of 51 adult patients were included of which 28 were male and 23 females. The mean age was 51.2±15.7 years. The mean serum creatinine at the time of biopsy was 7.05±4.57 mg/dl and the mean eGFR was 13.6±12.16 ml/min/1.73m2. There were 33 ANCA positive and 18 ANCA negative(35%) cases. Distribution of patients according to Berden’s histopathological classification was focal(4), crescentic(29), mixed(12) and sclerotic(6). The distribution of patients into risk categories based on renal risk score was low(8),medium(23) and high(20). Univariate Cox regression analysis showed that eGFR at biopsy (p 0.024), % IFTA (p 0.001) and % normal glomeruli in biopsy (p 0.023) are predictors of ESRD. Multivariate Cox regression analysis including age, eGFR, % IFTA and % normal glomeruli in biopsy also confirmed IFTA (p<0.001) and % normal glomeruli in biopsy (p 0.018) as significant predictors of ESRD. When % normal glomeruli was replaced by Berden’s histopathological classed it didn’t reach statistical significance to predict ESRD. Kaplan-Meier survival analysis for histological categories showed best renal survival in focal group and worst in sclerotic group (Log-Rank p=0.046). Kaplan-Meier analysis for the renal risk categories showed best survival in low risk group followed by medium and high risk groups respectively (Log-Rank p=0.002). Kaplan-Meier survival analysis was also done for percentage of normal glomeruli, IFTA and renal function. Conclusion In our study of Pauci-immune crescentic glomerulonpehritis ANCA was negative in 35% cases. Percentage of normal glomeruli, IFTA and eGFR at time of biopsy were important histopathological and clinical risk factors influencing renal survival in these patients. Results of our study validate that recently proposed renal risk score is a better predictor of survival (p=0.002) as compared to histological classification proposed by Berden (p=0.046).