4363.0.55.001 - Australian Health Survey: Users' Guide, 2011-13  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 11/12/2013   
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Contents >> Biomedical Measures >> Chronic Kidney Disease (CKD) biomarkers >> Estimated Glomerular Filtration Rate (eGFR)

ESTIMATED GLOMERULAR FILTRATION RATE (EGFR)

Definition

Estimated glomerular filtration rate (eGFR) measures the rate at which the kidneys filter wastes from the blood, and is considered to be the best measure of kidney function.1 Impaired eGFR levels indicate that the kidneys are not working properly, which can lead to Chronic Kidney Disease (CKD).

Population

eGFR was calculated based on serum creatinine (SCr) results, which were obtained for persons aged 12 years and over, who participated in the National Health Measures Survey (NHMS) and provided a blood sample. Note that only results for persons aged 18 years and over were published in the NHMS, as there is no validated eGFR formula for children. Fasting was not required for this test.

Methodology

A blood sample was collected from participants and SCr levels were measured at the Douglass Hanly Moir (DHM) laboratory.

In order to assess kidney function the estimated glomerular filtration rate was calculated using a SCr result in addition to a number of other variables such as age and sex. As such, eGFR was calculated at DHM using the following Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations2:


CKD-EPI equation
For females with SCr ≤ 62 mol/L: eGFR (mL/min/1.73 m2) = 144 × (SCr in mol/L × 0.0113/0.7)2 0.329 × (0.993)age in years
For females with SCr > 62 mol/L: eGFR (mL/min/1.73 m2) = 144 × (SCr in mol/L × 0.0113/0.7)2 1.209 × (0.993)age in years
For males with SCr ≤ 80 mol/L: eGFR (mL/min/1.73 m2) = 141 × (SCr in mol/L × 0.0113/0.9)2 0.411 × (0.993)age in years
For males with SCr > 80 mol/L: eGFR (mL/min/1.73 m2) = 141 × (SCr in mol/L × 0.0113/0.9)2 1.209 × (0.993)age in years


In the NHMS, cut off reference values for normal and abnormal results were sourced from the Chronic Kidney Disease (CKD) management guidelines by Kidney Health Australia.1 These guidelines are based on epidemiological data and publications of major clinical trials.

In the NHMS, the following definitions were used for eGFR:
  • Normal eGFR levels ≥ 60 mL/min/1.73 m2
  • Abnormal eGFR levels < 60 mL/min/1.73 m2.

Further test information about the analysis method and machine used to measure eGFR levels is available in Excel spreadsheet format in the Downloads page of this product.

Data items

The data items and related output categories for this topic are available in Excel spreadsheet format from the Downloads page of this product.

Interpretation

Points to be considered when interpreting data for this topic include the following:
  • eGFR test results do not confirm a specific diagnosis without consultation with a health professional.
  • There are a number of different test methods and equations to measure eGFR levels and they may produce different results. The data from this topic should therefore be used with caution when comparing eGFR results from other studies using a different test method or equation.
  • Note that the CKD-EPI equations are only validated for use with isotope dilution mass spectrometry - traceable creatinine assays and coefficients for race are not included, therefore when comparing this data with other sources of data, it should be interpreted with care.2

Comparability with other surveys

The NHMS is the first ABS survey to collect biomedical data on Chronic Kidney Disease.

Chronic Kidney Disease biomedical data has been collected in other non-ABS surveys. However, caution must be taken when interpreting results due to the differences in scope, assay and the instrument used, and any thresholds applied in the final analysis. Further information about these comparisons is available from the Comparisons with other Australian surveys section of the Biomedical Results for Chronic Diseases, 2011-12 publication.

ENDNOTES

1 Kidney Health Australia 2013, Chronic Kidney Disease (CKD) Management in General Practice. 2nd Edition 2012 <http://www.kidney.org.au/HealthProfessionals/CKDManagementinGeneralPractice/tabid/789/Default.aspx>, Last accessed 24/06/2013.
2 David W Johnson, Graham R D Jones, Timothy H Mathew, Marie J Ludlow, Matthew P Doogue, Matthew D Jose, Robyn G Langham, Paul D Lawton, Steven J McTaggart, Michael J Peake, Kevan Polkinghorne and Tim Usherwood, Australasian Creatinine Consensus Working Group 2012, Chronic kidney disease and automatic reporting of estimated glomerular filtration rate: new developments and revised recommendations, <https://www.mja.com.au/journal/2012/197/4/chronic-kidney-disease-and-automatic-reporting-estimated-glomerular-filtration>, Last accessed 27/07/2013.



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