Prognostic factors and validation of the histologic chronicity score for C3 glomerulopathy: a registry analysis

Abstract

Abstract Background 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 registry study, 74 patients from 20 centers with adequate follow-up data were included. Total chronicity score (TCS) was calculated according to percentages of glomerulosclerosis, interstitial fibrosis, tubular atrophy, and presence of arterio- and arteriolosclerosis. Primary composite outcome was defined as doubling of serum creatinine from baseline, undergoing dialysis or transplantation, development of stage 5 chronic kidney disease, or death. Results Median age was 34 (IQR: 24-46) years, and 39 patients (52.7%) were male. Median follow-up duration was 36 (IQR: 12-60) months, and median TCS was 3 (IQR: 1-5). Overall 19 patients (25.7%) experienced primary composite outcome. Multivariate Cox regression model showed that only hemoglobin [adjusted HR (aHR): 0.67, 95% CI: 0.46-0.97, p=0.035] predicted primary composite outcome, and TCS fell short of the statistical significance (aHR: 1.26, 0.97-1.64, p=0.08). ROC analysis demonstrated that TCS showed an AUC value of 0.68 (0.56-0.78, p=0.028) in discriminating primary composite outcome at 3 years, and 3-year kidney survival was lower in patients with TCS ≥4 (72.4%) compared to TCS <4 (91.1%) in Kaplan-Meier analysis (p=0.036). Conclusions Low hemoglobin levels predicted dismal outcomes in patients with C3G. TCS ≥4 was associated with a worse 3-year kidney survival, which validated the 3-year prognostic value of the TCS of C3G-HI in our population.