Evaluating long-term outcomes across eGFR equations in older adults

Introduction:The current diagnostic threshold for chronic kidney disease (CKD; estimated glomerular filtration rate [eGFR] <60 mL/min/1.73m) may lead to overdiagnosis in older adults.Additionally, no consensus exists regarding the optimal eGFR equation for use in older adults, despite considerable variability in calculations between equations.We investigated the impact of using eGFR equations validated for older populations (Berlin Initiative Study 1 [BIS1], and European Kidney Function Consortium [EKFC]) in place of the 2021 CKD-EPI creatinine equation (CKD-EPI2021) and assessed the implications of an age-adapted CKD definition (eGFR <45mL/min/1.73m).Methods: This cohort study used data from the ASPirin in Reducing Events in the Elderly (ASPREE) trial and its observational follow-up (ASPREE-eXtension).ASPREE enrolled community-dwelling older adults.Separate survival analyses compared the risk of reduced disability-free survival (DFS), its components, or major adverse cardiovascular events (MACE) between participants reclassified to a different CKD stage versus those who remained within the same stage when changing from CKD-EPI2021 to BIS1EKFC.Associations between eGFR and health outcomes were analyzed using restricted cubic splines referenced to eGFR 75m L /m in/1 .73m 2 .Results: Among 17,686 participants (mean age 75.14.3years), BIS1, and EKFC yielded eGFR values 12-15mL/min/1.73mlower than CKD-EPI2021; increasing CKD prevalence from 21% to 37-46%.Most participants moved to a higher CKD stage when changing from CKD-EPI2021 to BIS1, or EKFC; however, long-term outcomes were similar across reclassified and non-reclassified groups.Across all equations, risk of reduced DFS, all-cause mortality, or MACE was observed primarily below eGFR 45mL/min/1.73m,independent of urine albumin-to-creatinine ratio.