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Challenges in renally eliminated medication use: Evaluating cystatin C and serum creatinine eGFR discordance
Brandy N Hernandez1, Patrick M Wieruszewski1,2, Jason N Barreto1
1Department of Pharmacy, Mayo Clinic, Rochester, Minnesota, USA.
Insights
Estimating kidney function using serum cystatin C (CysC) reveals significant differences compared to serum creatinine in hospitalized patients. This kidney function discordance impacts the dosing of many renally eliminated medications, highlighting a critical patient safety concern.
Area of Science:
- Nephrology
- Clinical Pharmacology
- Biomarker Research
Background:
- Accurate estimation of Glomerular Filtration Rate (GFR) is essential for medication dosing in hospitalized individuals.
- Serum creatinine (Cr) has limitations for GFR estimation, prompting exploration of serum cystatin C (CysC) as an alternative biomarker.
- This study investigates the discordance between estimated GFR based on creatinine (eGFRCr) and cystatin C (eGFRCysC) in a large hospitalized patient cohort.
Purpose of the Study:
- To assess the extent of discordance between eGFRCr and eGFRCysC in hospitalized patients.
- To determine the frequency of renally eliminated medications affected by this eGFR discordance.
- To evaluate the clinical implications of GFR estimation discrepancies on medication management.
Main Methods:
- A multisite historical study analyzed data from hospitalized adults between 2011 and 2023.
- Concurrent serum creatinine and CysC measurements within 24 hours were used for analysis.
- eGFR discordance and the use of renally eliminated medications were described and quantified.
Main Results:
- 17,718 patients were included, with median eGFRCr of 65 mL/min and median eGFRCysC of 46 mL/min.
- 45% of patients exhibited a >30% absolute difference between eGFRCr and eGFRCysC.
- A significantly higher proportion of patients had eGFR <30 mL/min by eGFRCysC (26%) versus eGFRCr (15%).
- Patients were prescribed numerous medications, with 39% ± 13% being renally eliminated, and 80% of those with eGFR discordance received ≥5 renally eliminated drugs.
Conclusions:
- Substantial discordance exists between eGFRCysC and eGFRCr in hospitalized patients.
- This discordance directly impacts the dosing and management of renally eliminated medications.
- Further research is crucial to optimize pharmacotherapy for renally eliminated drugs in patients with discordant GFR assessments to enhance safety and efficacy.
Background:
Accurately estimating glomerular filtration rate (GFR) is crucial for dosing medications in hospitalized patients. Due to limitations of serum creatinine for GFR estimation, serum cystatin C (CysC) has been explored as an alternative functional kidney biomarker. This study assessed discordance between eGFRCr and eGFRCysC in a large sample of hospitalized patients and examined the frequency of renally eliminated medications affected by eGFR discordance.
Methods:
This multisite historical study included adults hospitalized between 2011 and 2023 with CysC and serum creatinine reported within 24 h of each other. The first concurrent biomarker pair for each patient was analyzed. eGFR discordance and use of renally eliminated medications were described.
Results:
17,718 hospitalized patients with concurrent creatinine and CysC assessments were included. The median eGFRCr was 65 mL/min, and the eGFRCysC was 46 mL/min. The median absolute difference of eGFRCr-eGFRCysC was 15 mL/min, and 7972 patients (45%) had a > 30% absolute difference. There was a significantly greater percentage of patients with an eGFR <30 mL/min based on eGFRCysC (26%) compared to eGFRCr (15%) (p < 0.001). Patients were prescribed an average of 20 medications in the 24 h surrounding the concurrent biomarker assessment. Renally eliminated medications accounted for 39% ± 13% of medication orders, and 80% of patients with eGFR discordance were prescribed five or more renally eliminated medications.
Conclusion:
Substantial eGFR discordance between eGFRCysC and eGFRCr was observed in hospitalized patients, which directly affects the dosing of renally eliminated medications. Further research is needed to optimize the pharmacotherapy of renally eliminated medications with discordant GFR assessments to improve medication safety and effectiveness.
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