Background and Importance Estimates of glomerular filtration rate (eGFR) should provide accurate measure of an individual’s kidney function. This is even more important in old people since there is age-related physiological change in the kidney, which could lead to reduced GFR. The overestimation of GFR may lead to drug toxicity and the underestimation may lead to sub-therapeutic drug levels.
Use of multiple equations to evaluate renal function can lead to differences and corresponding drug dosing regimens. The Cockcroft-Gault (CG) equation, despite inaccurate in the elderly, remains the most widely used equation for determining the creatinine clearance (CrCl). On the other hand, estimation of GFR using the CKD-EPI has gained increasing acceptance. This formula is used to classify chronic kidney disease.
Aim and Objectives To determine the correlation between estimated CrCl by CG with eGFR by CKD-EPI. Additionally, we have compared the differences among dose adjustments recommendations and evaluated the patient’s profile in the most discrepant results.
Material and Methods The study included hospitalised patients in the Medicine ward aged 70 and above with prescriptions of enoxaparin, meropenem, amoxicillin + clavulanate and piperacilin + tazobactam. Demographic data and serum creatinine (SrCr) were collected. CrCl was calculated using CG equation and eGFR by CKD-EPI 2021 equation.
Conclusion and Relevance In only four patients did difference in the estimation of renal function using the two equations, leading to different drug dosing recommendation. One patient had both enoxaparin and meropenem prescribed, all others only one drug. It seems that it is safe to use the CKD-EPI equation to drug dosing, with caution in patients with extreme weight and age characteristics. Future studies should extend to a greater number of patients and include other drugs with adjustment to renal function. In order to validate the estimated renal function and understand which formula is closest to reality, it would be important to determine the measured GFR. Controversy remains as to whether adoption of eGFR for drug dosing is appropriate given that dosing recommendations for many available drugs are based on CG estimates of kidney function. Using the same kidney function estimate for management of kidney disease, drug development and dosing would harmonise all clinical areas.
Conflict of Interest No conflict of interest
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