Volume 188 - Issue 7
Chronic kidney disease and automatic reporting of estimated glomerular filtration rate: revised recommendations
Authors: Timothy H Mathew, David W Johnson and Graham R D Jones, on behalf of the Australasian Creatinine Consensus Working Group
Med J Aust 2008; 188 (7): 427-430. || doi: 10.5694/j.1326-5377.2008.tb01700.x
Published online: 7 April 2008
Published online: 7 April 2008
In reply: We agree with Adam’s points that:
The estimated glomerular filtration rate (eGFR) represents a worthwhile advance on the plasma creatinine level for detecting kidney disease, and is currently the best readily available measure of GFR;
Educating the medical profession on the limitations of eGFR is important; and
Further refinements of eGFR accuracy are highly desirable.
Since the advent of automated laboratory reporting of eGFR, there has been a concerted effort by the Kidney Check Australia Taskforce to educate medical professionals and other clinicians about the strengths and limitations of eGFR and about how best to approach the patient with a significantly reduced eGFR. Education has been via printed office materials, accredited workshops, medical journal articles, online education, and decision-support systems embedded in medical software. Adding statements to laboratory reports has also been considered by the Australasian Creatinine Consensus Working Group, and some laboratories do provide explanatory eGFR statements. However, many have not embarked on this because of the difficulty of providing adequately informative explanatory remarks in very limited space.
Individual laboratories balance the need for such supporting information against the space requirements on reports and the diminishing effect of excessive repetition. Given that routine reports are already complex, often containing over 20 result items, and that many millions of reports with serum creatinine results are produced annually in Australia, the value of any repetitive comment needs careful consideration.
The response of clinicians to the introduction of automatic reporting of eGFR together with the linked educational campaign has been strongly positive, with outcomes that have included easier identification of chronic kidney disease, better decision making for affected patients, and more appropriate referral patterns, both in Australia and overseas. Nevertheless, we agree with Adam that eGFR is only an approximation of actual GFR and is subject to error. There are ongoing attempts to further improve the accuracy and clinical utility of eGFR through such ventures as the universal standardisation of creatinine calibration (which has already taken place in Australia and New Zealand) and the Chronic Kidney Disease Epidemiology Collaboration.1
McLachlan, on behalf of the Editorial Advisory Board of the Australian medicines handbook, reaffirms the Board’s position that eGFR is not appropriate for use in dosage calculations. However, for the reasons stated in the consensus document,2 we remain convinced that eGFR is a useful tool for most drug dosing decisions.
We note with interest the recent change in the position taken by the British National Formulary (BNF 54) to one of support for the Modification of Diet in Renal Disease (MDRD)-based eGFR1 being used in place of creatinine clearance rate “for most drugs and for most patients of average build and height”3 — a stance similar to ours. In particular, we re-emphasise that eGFR, because of its ready availability, increases the rate of identification of renal failure.
We agree with McLachlan that prescribers should continue to follow specific published recommendations for drugs such as enoxaparin and gentamicin (these are good examples of “critical-dose drugs” in the hospital setting). We note additionally that there is increasing acceptance of the eGFR in the drug literature. In the case of enoxaparin, the MDRD equation for eGFR has been used to assess the effect of renal function on bleeding in elderly patients4 and has been found to provide the best relationship with enoxaparin clearance in this setting.5
The eGFR is now an established feature of pathology reports in Australia, and we believe it is important to integrate this information into routine practice for drug dosing decisions. We therefore offer to work with the authors of the Australian medicines handbook and other interested parties to develop guidelines for drug dosing decisions using all available information.
References
- Levey AS, Coresh J, Greene T, et al; Chronic Kidney Disease Epidemiology Collaboration. Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate. Ann Intern Med 2006; 145: 247-254.
- Mathew TH, Johnson DW, Jones GRD, on behalf of the Australasian Creatinine Consensus Working Group. Chronic kidney disease and automatic reporting of estimated glomerular filtration rate: revised recommendations. Med J Aust 2007; 187: 459-463. 0_i1091845
- British National Formulary. What’s new in BNF 54? Renal function and drugs. http://www.bnf.org/bnf/extra/current/450035.htm (accessed Jan 2008).
- Thorevska N, Amoateng-Adjepong Y, Sabahi R, et al. Anticoagulation in hospitalized patients with renal insufficiency: a comparison of bleeding rates with unfractionated heparin vs enoxaparin. Chest 2004: 125: 856-863. 0_i1091849
- Berges A, Laporte S, Epinat M, et al. Anti-factor Xa activity of enoxaparin administered at prophylactic dosage to patients over 75 years old. Br J Clin Pharmacol 2007; 64: 428-438. 0_i1091851