Using the Kinetic Estimating Glomerular Filtration Rate Equation for Estimating Glomerular Filtration Rate and Detecting Acute Kidney Injury: A Pilot Study

Abstract

Background: Estimating the glomerular filtration rate (eGFR) when the creatinine (Cr) is rapidly changing, as in acute kidney injury (AKI), has been a challenge. The Kinetic Estimated Glomerular Filtration Rate (KeGFR) formula by S. Chen estimates the GFR in the acute state by factoring the time interval between rising Cr values and the volume of distribution (V_D). It provides the clinician with an eGFR value for each non-steady state Cr value. We applied the KeGFR formula to detect AKI in an adult non-ICU inpatient setting. We then compared KeGFR with the current standard Acute Kidney Injury Network (AKIN criteria) and Risk Injury Failure Loss End-Stage Kidney Disease (RIFLE criteria) and new criteria (Waikar-Bonventre, Delta check) for AKI detection. Methods: A total of 250 consecutive adult patients admitted to the Medical wards were screened. Patient episodes with a change in Cr of > 4.3% (Biological Variation) were included in the study (n = 80). The KeGFR equation was applied to this cohort after calculating the V_D individually after estimating the initial GFR by using MDRD equation. A fall in KeGFR of 25% or more was considered as AKI. The AKIN, Waikar-Bonventre, RIFLE, and Delta Check criteria were also applied to this cohort and compared with the KeGFR criterion. Clinical adjudication was performed when there was discordance between AKI episodes detected by AKIN and KeGFR criteria. Results: There were 50 episodes of AKI by AKIN classification and 31 episodes by KeGFR criterion. All but 1 (30) episode detected by KeGFR criterion fulfilled the AKI definition by AKIN. AKIN diagnosed an additional 20 episodes. However, all of these had an elevated Cr level on admission; thus, requiring the incorporation of baseline Cr by AKIN which is not part of the KeGFR formula. Five of these 20 patients were deemed as not having AKI by clinical adjudication. All patients with in-hospital AKI and ongoing AKI were detected by both the criteria. The KeGFR criteria detected almost all (24/25) episodes of AKI identified by the Waikar-Bonventre method. The latter method detected 77% (24/31) of the AKI episodes identified by KeGFR. Conclusion: The KeGFR equation can be readily applied to estimate GFR in the non-steady state. A KeGFR-based criterion successfully detected ongoing and in-hospital AKI in this study. Community acquired AKI that did not progress after admission was not detected by the KeGFR criterion.

The kinetic estimated glomerular filtration rate ratio predicts acute kidney injury

“…14 KeGFR has been trialled in small studies for prediction of delayed graft function, 15 and of AKI in critical care 16 and after cardiac surgery. 17 It has also been used to attempt to detect AKI in the general hospital population, 18 although a decrease in GFR is presently not part of the KDIGO criteria for diagnosis of AKI. Instead, the current criteria for AKI diagnosis are based on changes in serum creatinine and urine output either within 48 h or 7 days following injury.…”

Using Kinetic eGFR for Drug Dosing in AKI: Concordance between Kinetic eGFR, Cockroft-Gault Estimated Creatinine Clearance, and MDRD eGFR for Drug Dosing Categories in a Pilot Study Cohort

“…Essentially, all patients with in-hospital AKI were detected using kinetic eGFR. (Details of the methodology and results are available in the original paper and in the supplementary paper [6]. )…”

“…The kinetic equation by Chen (KeGFR) estimates GFR for the nonsteady-state Cr level and is being validated in patient cohorts with acute kidney injury (AKI) [1][2][3][4][5]. In our pilot study, we were able to apply the KeGFR equation to detect AKI among acute medical admissions [6]. In this cohort with rapidly changing Cr, a KeGFR-based criterion detected almost all patients with in-hospital AKI as determined by the Acute Kidney Injury Network (AKIN) criteria and clinical adjudication.…”

Estimating Creatinine Clearance in the Nonsteady State: The Determination and Role of the True Average Creatinine Concentration

“…The original algebraic equation has been tested extensively in clinical research and has performed admirably. 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 In 2018, the GFR K equation was upgraded with calculus to accommodate a volume that changes steadily. 3 To remodel the algebraic into a calculus version, we had to figure out the exact substitute for the mean.…”