Natalie Klein
Virginia Commonwealth University Health System
Richmond, VA
Disclosure information not submitted.
Payal Kakadiya, PharmD, BCPS
Pharmacist
Virginia Commonwealth University Health System, United States
Disclosure information not submitted.
Graham Gipson, MD
Physician
Virginia Commonwealth University Health System, United States
Disclosure information not submitted.
Anna Vinnikova, MD
Physician
Virginia Commonwealth University Health System, United States
Disclosure information not submitted.
Rachel Flurie, PharmD, BCPS
Pharmacist
Virginia Commonwealth University Health System, United States
Disclosure information not submitted.
Title: Predictors of Discordance in eGFR Using Serum Creatinine Versus Cystatin-C
Introduction: Clinicians estimate renal function utilizing serum creatinine (SCr). However, SCr can be affected by age, sex, muscle mass, and renal tubular secretion. Cystatin (Cys-C) is produced by all nucleated cells, freely filtered in the renal tubules, and not greatly influenced by patient factors. Glomerular filtration rate (GFR) equations using Cys-C and SCr (eGFRCys-C/SCr) have shown to be comparable to measured GFR. Currently, there are no recommendations on when Cys-C levels should be measured to assess renal function and optimize medication dosing. The aim of this study is to identify independent clinical predictors of discordance between eGFRSCr and eGFRCys-C/SCr.
Methods: This study is a single center, retrospective chart review of hospitalized adult patients for whom a Cys-C level was obtained from January 2019 to December 2020. Data collected included demographic information (i.e., age, sex, race, weight, SCr, Cys-C), clinical data identified by preexisting diagnoses (i.e., chronic kidney disease, cirrhosis, tetraplegia, and malnutrition) and renal estimation (eGFRSCr, eGFRCys-C/SCr). Patients were stratified into one of eight eGFR octiles (0–15, 16–30, 31–45, 46–60, 61–75, 76–90, 91–105, and 106–120 mL/min per 1.73 m2). Cross-tabulation of octile-based eGFRSCr and eGFRCys-C/SCr classifications allowed identification of eGFR concordance or discordance. Patient covariates were assessed utilizing a logistic regression model to explore potential independent risk factors for discordant eGFR.
Results: Of the 496 patients reviewed, 243 patients were included. The logistic regression model indicates serum albumin (P= 0.015) and malnutrition (P= 0.042) as statistically significant predictors of discordance between eGFRSCr and eGFRCys-C/SCr octile classifications. The odds ratio (OR) for discordance for a unit change in serum albumin was 0.53 (95% CI: 0.31–0.88), and malnutrition was 2.68 (95% CI: 1.04–6.92). Age showed a trend toward statistical significance and predicted a modest increase in probability of eGFR octile discordance (OR 1.02; 95% CI: 1.02–1.04).
Conclusions: The results of this study suggest clinicians should consider checking a Cys-C to better assess renal function in patients who have low serum albumin, malnutrition, or are of older age.