Chronic kidney disease and automatic reporting of estimated glomerular filtration rate: new developments and revised recommendations

Abstract

The publication of the Australasian Creatinine Consensus Working Group's position statements in 2005 and 2007 resulted in automatic reporting of estimated glomerular filtration rate (eGFR) with requests for serum creatinine concentration in adults, facilitated the unification of units of measurement for creatinine and eGFR, and promoted the standardisation of assays. New advancements and continuing debate led the Australasian Creatinine Consensus Working Group to reconvene in 2010. The working group recommends that the method of calculating eGFR should be changed to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula, and that all laboratories should report eGFR values as a precise figure to at least 90 mL/min/1.73 m(2). Age-related decision points for eGFR in adults are not recommended, as although an eGFR < 60 mL/min/1.73 m(2) is very common in older people, it is nevertheless predictive of significantly increased risks of adverse clinical outcomes, and should not be considered a normal part of ageing.If using eGFR for drug dosing, body size should be considered, in addition to referring to the approved product information. For drugs with a narrow therapeutic index, therapeutic drug monitoring or a valid marker of drug effect should be used to individualise dosing. The CKD-EPI formula has been validated as a tool to estimate GFR in some populations of non-European ancestry living in Western countries. Pending publication of validation studies, the working group also recommends that Australasian laboratories continue to automatically report eGFR in Aboriginal and Torres Strait Islander peoples. The working group concluded that routine calculation of eGFR is not recommended in children and youth, or in pregnant women. Serum creatinine concentration (preferably using an enzymatic assay for paediatric patients) should remain as the standard test for kidney function in these populations.

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

“…As the CKD-EPI equation is emerging as the preferred equation in clinical laboratories for estimating GFR, 38 the examination of its performance in the drug-dosing setting is important, as ideally a single equation should be used for any scenario where an estimate of GFR is required. Most dose adjustment is concerned with patients with impaired renal function.…”

Enzymatic creatinine assays allow estimation of glomerular filtration rate in stages 1 and 2 chronic kidney disease using CKD-EPI equation

“…Once again, the better accuracy of the CKD-EPI equation is purely analytical. One of the most recent recommendations published comes from the Australasian Creatinine Consensus Working Group which recommended the use of CKD-EPI equation and a numerical expression at least up to 90 mL/min/1.73 m 2 [19]. Our study provides a basis for such recommendations and even extends it to eGFR as high as 120 mL/min/1.73 m 2 , as long as an accurate enzymatic assay is used.…”

The Uncertainty of the eGFR

“…Recently, however the revised recommendations of the Australian Creatinine Consensus Group did not agree with age related reference intervals. In the study of patients with eGFRs of between 45 and 60 mL/min/1.73 m 2 and no albuminuria there was no difference in mortality from kidney disease in those above to those below 65 years [13]. However, Roderick [14] has shown that older patients ([75) commonly had eGFRs \60 mL/min/1.73 m 2 but there did not appear to be associated adverse pathophysiologic consequences until the eGFR fell to less than 45 mL/min/1.73 m 2 .…”