Impact of Estimated Glomerular Filtration Rate Equations on Vancomycin Dosing and Treatment Outcomes

Vancomycin has a narrow therapeutic window and is primarily renally excreted. This study explored whether varied estimated glomerular filtration rate (eGFR) equations lead to differences in chronic kidney disease (CKD) staging and vancomycin dosage, and their impact on treatment outcomes.

This cross-sectional study retrospectively included adult patients receiving vancomycin for therapeutic purposes (empirical or targeted therapy) at Nanjing Drum Tower Hospital (2019-2023). Consistency of each of the metrics (eGFR values, CKD staging, dose staging, and staging recommendations) derived from different equations was compared. Incidences of distinct clinical outcomes were compared among patients receiving doses recommended by different eGFR equations. Logistic regression analyzed associations between inconsistent status and patient characteristics as well as clinical outcomes.

A total of 832 patients were identified. The Chinese population-adjusted creatinine (Cr)-based European Kidney Function Consortium equation (EKFC-eGFRCr[CN]) had the smallest impact on dosing adjustments (3.4%), whereas the cystatin(Cys)-based Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation (CKD-EPI-eGFRCys) had the largest impact (16.0%) and exhibited favorable performance in target vancomycin trough concentration (C_min) attainment and other clinical outcomes (except for target 24 h area under the concentration-time curve [AUC_0~24]). Only staging discordance between the Xiangya equation and EKFC-eGFRCr+Cys was associated with a reduced C_min attainment rate. When dosing recommendations disagreed with those from the Cockcroft-Gault equation, all eGFR equations except the Xiangya equation were associated with higher C_min attainment rates.

Our study found that the CKD-EPI-eGFRCys equation required the most dosing adjustments, while the EKFC-eGFRCr(CN) equation required the fewest. Preferentially using the CKD-EPI-eGFRCys equation was optimal for target attainment of key clinical outcomes.