The value of the current histological scores and classifications of ANCA glomerulonephritis in predicting long-term outcome

Background. Three different histological scores—histopathologic classification (Berden), Renal Risk Score (RRS) and the Mayo Clinic Chronicity Score (MCCS)—for anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (ANCA-GN) were compared to evaluate their association with patient and kidney prognosis of ANCA-GN. Methods. Patients aged >18 years with at least 1 year of follow-up and biopsy-proven ANCA-GN entered this retrospective study. Renal biopsies were classified according to Berden’s classification, RRS and MCCS. The first endpoint was end-stage kidney disease (ESKD), defined as chronic dialysis or estimated glomerular filtration rate <15 mL/min/1.73 m2. The second endpoint was ESKD or death. Results. Of 152 patients 84 were males, with median age of 63.8 years and followed for 46.9 (interquartile range 12.8–119) months, 59 (38.8%) reached the first endpoint and 20 died. The Kaplan–Meier curves showed that Berden and RRS were associated with first (Berden: P = .004, RRS: P < .001) and second (Berden: P = .001, RRS: P < .001) endpoint, MCCS with the first endpoint only when minimal + mild vs moderate + severe groups were compared (P = .017), and with the second endpoint (P < .001). Among the clinical/histological presentation features, arterial hypertension [odds ratio (OR) = 2.75, confidence interval (95% CI) 1.50–5.06; P = .0011], serum creatinine (OR = 1.17, 95% CI 1.09–1.25; P < .0001), and the percentage of normal glomeruli (OR = 0.97, 95% CI 0.96–0.99; P = .009) were the independent predictors of ESKD at multivariate analysis. When the three scores were included in multivariate analysis, RRS (OR = 2.21, 95% CI 1.15–4.24; P = .017) and MCCS (OR = 2.03, 95% CI 1.04–3.95; P = .037) remained predictive of ESKD, but Berden (OR = 1.17, 95% CI 0.62–2.22; P = .691) did not. Conclusion. RRS and MCCS scores were independent predictors of kidney survival together with high serum creatinine and arterial hypertension at diagnosis, while Berden classification was not.