#3524 INCIDENCE AND OUTCOMES OF KIDNEY REPLACEMENT THERAPY FOR END-STAGE KIDNEY DISEASE DUE TO PRIMARY GLOMERULONEPHRITIS IN THE ERA REGISTRY
Authors: Elhafeez Samar Abd , Kramer Anneke , Pippias Maria , Ortiz Alberto , Jager Kitty J , Stel Vianda ,   ERA Registry representatives
Published: June 2023

Abstract

Background and Aims
Primary glomerulonephritis (PGN) is among the leading causes of end-stage kidney disease (ESKD) in patients initiating kidney replacement therapy (KRT). To date, most studies have examined KRT outcomes from all PGN subgroups combined. Using data from the European Renal Association (ERA) Registry we examined trends and outcomes in individuals with PGN and its subgroups commencing KRT. Firstly, we described the incidence of KRT for ESKD due to PGN for all countries combined and by country; and secondly, we compared patient characteristics, survival outcomes, and causes of death.

Method
We used data from 31 national and regional renal registries providing individual patient data to the ERA Registry for at least three years between 2000-2019. PGN was categorized into six subgroups based on the ERA primary renal disease codes: Immunoglobulin A nephropathy [IgAN], membroproliferative glomerulonephritis [MPGN] (type I and type II), membranous nephropathy [MN], focal segmental glomerulosclerosis [FSGS], crescentic glomerulonephritis [crescentic GN], and other PGN (histologically examined and histologically not examined). The age-and-sex-standardized incidences were estimated using the 2015 EU28 population as a reference. Joinpoint regression analysis was used to determine the annual percentage change (APC) in the incidence. Kaplan Meier and Cox regression analyses were used for the survival analyses. We adjusted for age, sex, KRT initiation era, and country.

Results
In total, 69,854 individuals started KRT due to PGN between 2000-2019, of whom 27.8% had IgAN, 15.8% FSGS, 8.5% MPGN, 5.8% crescentic GN, and 4.5% MN. The remaining 37.7% were categorized as” other PGN’’ (14.1% not biopsied). The standardized incidence of KRT due to PGN was 16.6 per million population (pmp), ranging from 8.8 pmp in Serbia to 20.0 pmp in France. The incidence was the highest for IgAN (4.6 pmp) and FSGS (2.6 pmp) particularly in age group 65-74 year. The incidence of KRT due to PGN [APC: -1.8% (-2.2; -1.4)] declined between 2000-2013, then it stabilized. Conversely, the incidence of KRT due to IgAN [APC: 5.1% (2.7;7.6)] between 2012-2019 and due to FSGS [APC: 3.1% (2.3-3.8)] between 2000-2019 increased. During a five-year follow-up 8,928 patients died. The five-year survival probabilities varied from 57.0% for crescentic GN to 83.6% for IgAN. The risk of death was highest in crescentic GN [The adjusted hazard ratio: 1.8 (95% confidence interval: 1.6-1.9)] compared to IgAN. Cardiovascular disease was the most common cause of death (33.9%) followed by infection (18.5%).

Conclusion
The incidence of KRT due to PGN was highest in IgAN and FSGS and varied largely across the European countries. The number of non- histologically examined PGN cases remains high, especially in Eastern Europe, which may reflect a lack of renal biopsy facilities which in turn hamper reporting of the true histological diagnosis. There was an initial decline in the incidence of KRT due to PGN, followed by stabilization. This could imply advances in the management protocols with better prognosis. Further studies are needed to explain the observed difference in the incidence over time and to identify factors leading to less initiation of KRT among patients with PGN.