The performances of the Cockcroft-Gault, Modification of Diet in Renal Disease Study and Chronic Kidney Disease Epidemiology Collaboration equations in predicting gentamicin clearance

Abstract

Background: It is unclear which renal function equation, employing an isotope dilution mass spectrometry (IDMS)-aligned creatinine assay, best predicts gentamicin clearance. Methods: The performances of the Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD) Study and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations for predicting gentamicin clearances were assessed retrospectively in 240 patients treated with gentamicin during 2011-2012, when the local creatinine assay was IDMSaligned. Comparisons were based on the percentage within 30% of gentamicin clearance (P 30 ) and the root-mean-square error (RMSE) of each equation. Gentamicin clearance was calculated from plasma concentrations using a one-compartment model. Results: The Cockcroft-Gault equation and the CKD-EPI equation corrected for individual body surface area (BSA) were associated with the highest P 30 (69% and 67%, respectively) and lowest RMSE (39 and 36 mL/min, respectively) in the 240 patients. Correction for individual BSA improved the performances of the MDRD Study and CKD-EPI equations in patients with body mass indices <18.5 or 530 kg/m 2 . The equations systematically underestimated gentamicin clearance as gentamicin clearance increased, with performance being inferior with gentamicin clearance 590 versus <90 mL/ min. Conclusions: The CKD-EPI equation corrected for individual BSA, and the Cockcroft-Gault equation, provided the best estimates of gentamicin clearance. The CKD-EPI and MDRD Study equations should be corrected for individual BSA at the extremes of body size, if used for guiding gentamicin therapy. The performances of the equations were inferior in patients with higher values of gentamicin clearance.

Adaptation posologique des médicaments et fonction rénale : quel(s) estimateur(s) faut-il choisir ?

“…En effet, il n'existe pas de consensus clair quant au poids qui doit effectivement être utilisé dans la formule de Cockcroft : poids ré el, poids idé al calculé , poids ajusté , poids « maigre » [26]. Des donné es de simulation ont illustré des discordances significatives en termes d'adaptations posologiques selon que l'un ou l'autre de ces « poids » é tait utilisé , par exemple lorsque des populations obè ses, ou à l'inverse dé nutries, sont considé ré es [47,48,[51][52][53][54][55][56][57][58].…”

“…Les é tudes sur la pré diction de la clairance de mé dicaments (le plus souvent les aminoglycosides et la vancomycine) par les diffé rentes é quations sont plus rares et les ré sultats contradictoires [48,51,58,76,[84][85][86][87][88][89]. Enfin, une autre façon d'illustrer les é ventuelles discordances entre les é quations est de reprendre des donné es d'é tudes cliniques observationnelles ou interventionnelles et de vé rifier si les conclusions des dites é tudes resteraient identiques en utilisant l'é quation de Cockcroft (comme cela a é té fait de prime abord dans la plupart des é tudes) ou une autre é quation.…”

“…Il est tout à fait correct d'affirmer que ré aliser une mesure de DFG via une mesure de la clairance urinaire de l'inuline reste quelque chose de compliqué [107]. Il existe cependant des mé thodes alternatives, plus simples pratiquement et moins coû teuses, comme la mesure de la clairance plasmatique d'iohexol ou du 51 Cr-EDTA (acide é thylè ne-diamine-té tra-acé -tique) [29,31]. Une telle mesure ne peut cependant pas s'envisager chez tous les patients et dans tous les hôpitaux.…”

Letter by Chin et al Regarding Article, “Efficacy and Safety of Dabigatran Compared With Warfarin in Relation to Baseline Renal Function in Patients With Atrial Fibrillation: A RE-LY (Randomized Evaluation of Long-Term Anticoagulation Therapy) Trial Analysis”

“…This is important because the CKD-EPI equation was developed using creatinine measured by IDMS-aligned assays, and is not necessarily applicable to creatinine concentrations measured using assays that are not IDMS-aligned. [2][3][4] In addition, the '186' version of the Modification of Diet in Renal Disease (MDRD) Study equation was used in this study, instead of the '175' version that was specifically derived for use with IDMS-aligned assays.3 It is difficult to gauge whether the results reported by Hijazi et al will have any bearing on current dabigatran dosing practice until this aspect of the analytical methods is clarified.It is unclear what units were used in the data analysis for the estimated glomerular filtration rate (eGFR) calculated by the CKD-EPI equation. In the Abstract and Discussion section of the article, the units are stated as mL/min, whereas in the Results section the CKD-EPI eGFR was expressed as mL/min per 1.73 m 2 of body surface area.…”

“…This is important because the CKD-EPI equation was developed using creatinine measured by IDMS-aligned assays, and is not necessarily applicable to creatinine concentrations measured using assays that are not IDMS-aligned. [2][3][4] In addition, the '186' version of the Modification of Diet in Renal Disease (MDRD) Study equation was used in this study, instead of the '175' version that was specifically derived for use with IDMS-aligned assays.…”