The performance of contemporary cystatin C‐based GFR equations in predicting gentamicin clearance

Abstract

AIMSWe aimed to compare the performances of contemporary cystatin C (Cys)-based GFR equations, and the creatinine only Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation for predicting gentamicin clearance. METHODSThe bias and imprecision of the CKD-EPI, CKD-EPI_Cys and creatinine-cystatin C CKD-EPI (CKD-EPI_CrCys) equations for predicting gentamicin clearances, were assessed in 260 patients treated with gentamicin during 2012-2013. The creatinine-cystatin C Berlin Initiative Study equation (BIS_CrCys) was examined in the ≥70 year subgroup. The reference gentamicin clearance was calculated using post-dose plasma concentrations. RESULTSThe CKD-EPI_CrCys equation had the highest percentage of estimates within 30% of the reference gentamicin clearance (70%, P = 0.003) and lowest root mean square error (95% CI) of 29 (25, 23) ml min −1 of the three equations for the entire cohort. There was no significant improvement in the performances of the equations with the exclusion of 41 patients with abnormal thyroid function tests or steroid co-prescription at the time of the index gentamicin dose. Of the remaining 219 patients, adjustment for individual BSA improved the performances of all GFR equations (P ≤ 0.003) in those with body mass indices (BMI) <18.5 or ≥30 kg m CONCLUSIONSThe CKD-EPI_CrCys equation provided the best estimate of gentamicin clearance. If used for guiding gentamicin dosing, the results from GFR equations should be adjusted for individual BSA at the extremes of body size.

Removal of body surface area normalisation improves raw‐measured glomerular filtration rate estimation by the Chronic Kidney Disease Epidemiology Collaboration equation and drug dosing in the obese

“…The removal of the 1.73 m 2 normalisation by accounting for individual BSA in all patients showed that the CKD‐EPI_noBSA (mL/min) also provided results which were less biased and comparable at predicting Tc‐DTPA GFR (mL/min) at higher levels of GFR and BMI. The superiority of the CKD‐EPI_noBSA over the CKD‐EPI equation has similarly been shown in the prediction of gentamicin clearances …”

“…The superiority of the CKD-EPI_noBSA over the CKD-EPI equation has similarly been shown in the prediction of gentamicin clearances. 23,24 Redal-Baigorri et al reported that removal of BSA normalisation with the CKD-EPI equation (mL/min) was less biased than using the CKD-EPI equation (mL/min/ 1.73 m 2 ) in predicting GFR (mL/min) measured using Cr-EDTA, 25 but did not report any comparative statistics regarding the performance of the CKD-EPI equation with and without BSA normalisation. Lemoine et al reported from their study comprising obese patients, that CKD-EPI equation (mL/min/1.73 m 2 ) had less bias in the prediction of measured GFR (mL/min) than in the prediction of measured GFR normalised for BSA (mL/min/1.73 m 2 ).…”

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.…”

A Correlation Analysis of Serum Creatinine Based eGFR and Serum Cystatin C Based eGFR with Thyroid Dysfunction Patients

“…Conversely, in overt hyperthyroidism, blood volume and glomerular filtration pressure increase due to increase of cardiac output, RAS activation and increase of RBF, resulting in increase of GFR [4][5][6][7][8]. Best known method of measuring GFR is to directly administer external markers like Inulin, Iohexol, Due to difficulty of having to directly administer markers on the patient, GFR is evaluated quickly and easily using a formula based on internal markers like serum creatinine, cystatin C, etc [9][10][11]. Thyroid dysfunction is known to play an important role in renal function changes.…”