Impact of Serum Cystatin C-Based Glomerular Filtration Rate Estimates on Drug Dose Selection in Hospitalized Patients.
Pharmacotherapy. 2018 Aug 18;:
Authors: Peters BJ, Rule AD, Kashani KB, Lieske JC, Mara KC, Dierkhising RA, Barreto EF
STUDY OBJECTIVE: Serum creatinine concentration (SCr) is used to estimate glomerular filtration rate (eGFR) for medication dosing. Serum cystatin C concentration (CysC) has been proposed as an adjunct or alternative to SCr. This study sought to evaluate the impact that using CysC in eGFR equations could have on drug dose recommendations in hospitalized patients with infections.
DESIGN: Retrospective analysis of prospectively collected data.
SETTING: Large academic tertiary care medical center.
PATIENTS: Three hundred eight adults with suspected or documented infections and stable kidney function who were hospitalized between 2012 and 2015.
MEASUREMENTS AND MAIN RESULTS: Standardized SCr and CysC measured at the time of antibiotic dosing were used to estimate GFR from the three Chronic Kidney Disease Epidemiology Collaborative (CKD-EPI) equations using SCr (eGFRCr ), CysC(eGFRcysC ), or combination SCr and CysC (eGFRCr-cysC ), and these values were compared with estimated creatinine clearance from the Cockcroft-Gault equation (eCrCl; standard of care for drug dosage adjustments). The eGFRs were categorized into five common dosage adjustment strata (< 20, 20-49, 50-79, 80-130, and > 130 ml/min), and agreement between equations was tested with the weighted kappa statistic. Recommended drug dosesvaried considerably between the eCrCl and the CKD-EPI equations (weighted kappa [95% confidence interval]: eGFRCr 0.73 [0.68-0.79], eGFRcysC 0.42 [0.35-0.5], eGFRCr-cysC 0.65 [0.6-0.71]). If eGFRCr, eGFRcysC , or eGFRCr-cysC were used instead of eCrCl to dose drugs, 11%, 12%, and 8% of doses, respectively, would be higher, and 12%, 38%, and 24% of doses, respectively, would be lower.
CONCLUSION: Significant discordance in drug doses was observed when the CKD-EPI equations were used in place of eCrCl. When CysC was included in eGFR equations, recommended doses were often lower. Further study is needed to develop and test drug-specific dosing guidelines which incorporate alternate renal biomarkers and/or more contemporary eGFR equations. This article is protected by copyright. All rights reserved.
PMID: 30120844 [PubMed - as supplied by publisher]