#3093 PROGNOSTIC FACTORS AND VALIDATION OF THE HISTOLOGIC CHRONICITY SCORE FOR C3 GLOMERULOPATHY: A REGISTRY ANALYSIS

Abstract

Abstract Background and Aims Data on prognostic factors of C3 glomerulopathy (C3G) are limited, and validation of the new C3G histologic index (C3G-HI) in different settings is still needed. We aimed to evaluate the chronicity score of C3G-HI and probable prognostic factors in our population. Methods In this prospective registry, 99 patients with C3G were identified, and 74 patients from 20 centers with adequate follow-up data were included. Total chronicity score (TCS) (0-10) was calculated according to percentages of glomerulosclerosis, interstitial fibrosis (IF), tubular atrophy (TA), and presence of arterio- and arteriolosclerosis [1]. Study outcome was defined as doubling of serum creatinine from baseline, undergoing dialysis or transplantation, development of stage 5 chronic kidney disease (eGFR <15 ml/min/1.73 m2 by CKD-EPI 2009 equation), or death. Results Baseline features, treatment characteristics and outcomes were detailed in Table 1. Median follow-up duration was 36 (12-60) months. Overall, 19 patients (25.7%) experienced the study outcome over a median of 24 (6-51) months. Three patients died due to infections (n = 2) and unknown causes (n = 1) including a patient who died shortly after becoming dialysis-dependent. Median TCS was 3 (1-5). Univariate analyses showed that IF, hemoglobin, serum creatinine and serum albumin levels were associated with the outcome, but only grade 3 IF predicted the outcome in multivariate Cox regression (HR: 6.623, 95% CI: 1.269-34.564, p = 0.025). Since the median follow-up was 36 months, separate analyses for the outcome at 3 years were conducted. IF, TA, TCS, hemoglobin, serum creatinine and albumin were associated with the outcome in univariate analyses. In a multivariate Cox regression model encompassing IF, TA, hemoglobin, serum creatinine and albumin, only hemoglobin was identified as a predictor. A second model including TCS instead of IF and TA demonstrated that TCS (HR: 1.288, 1.021-1.626, p = 0.033) and hemoglobin (HR: 0.617, 0.407-0.935, p = 0.023) predicted the study outcome. Kaplan-Meier analysis showed that 3-year kidney survival was lower in patients with TCS ≥4 (72.4%) compared to TCS <4 (91.1%) (p = 0.036) (Figure 1). Conclusions TCS ≥4 and lower hemoglobin levels at diagnosis predict the 3-year kidney survival in patients with C3G, which validates the chronicity score of C3G-HI.