Estimated glomerular filtration rate from the renal hypothermia trial: clinical implications

Abstract

ObjectiveTo assess if estimated glomerular filtration rate (eGFR) can replace measured GFR (mGFR) in partial nephrectomy (PN) trials, using data from a randomised clinical trial.Patients and methodsWe conducted a post hoc analysis of the renal hypothermia trial. Patients underwent mGFR with diethylenetriaminepentaacetic acid (DTPA) plasma clearance preoperatively and 1 year after PN. The eGFR was calculated using the 2009 Chronic Kidney Disease Epidemiology Collaboration (CKD‐EPI) creatinine equations incorporating age and sex, with and without race: 2009 eGFRcr(ASR) and 2009 eGFRcr(AS), and the 2021 equation that only incorporates age and sex: 2021 eGFRcr(AS). Performance was evaluated by determining the median bias, precision (interquartile range [IQR] of median bias), and accuracy (percentage of eGFR within 30% of mGFR).ResultsOverall, 183 patients were included. Pre‐ and postoperative median bias and precision were similar between the 2009 eGFRcr(ASR) (−0.2 mL/min/1.73 m2, 95% confidence interval [CI] −2.2 to 1.7, IQR 18.8; and −2.9, 95% CI −5.1 to −1.5, IQR 15, respectively) and 2009 eGFRcr(AS) (−0.3 mL/min/1.73 m2, 95% CI −2.4 to 1.5, IQR 18.8; and −3.0, 95% CI −5.7 to −1.7, IQR 15.0, respectively). Bias and precision were worse for the 2021 eGFRcr(AS) (−8.8 mL/min/1.73 m2, 95% CI −10.9 to −6.3, IQR 24.7; and −12.0, 95% CI −15.8 to −8.9, IQR 23.5, respectively). Similarly, pre‐ and postoperative accuracy was >90% for the 2009 eGFRcr(ASR) and 2009 eGFRcr(AS) equations. Accuracy was 78.6% preoperatively and 66.5% postoperatively for 2021 eGFRcr(AS).ConclusionThe 2009 eGFRcr(AS) can accurately estimate GFR in PN trials and could be used instead of mGFR to reduce cost and patient burden.