Forthcoming Change in eGFR Calculation Methodology

FAO: Tower Hamlets, Newham and Waltham Forest GPs and Barts Health.

This affects adult patients in the care of Tower Hamlets, Newham and Waltham Forest GPs and Barts Health.

We want to inform you about an important change in how estimated glomerular filtration rate (eGFR) is being calculated in our laboratory reports. As of Monday 28^th April, our laboratories will be transitioning from the MDRD (Modification of Diet in Renal Disease) equation to the CKD-EPI 2009 (Chronic Kidney Disease Epidemiology Collaboration) equation to calculate eGFR as recommended by NICE, NHS England and GIRFT. This shift is intended to improve the accuracy of kidney function assessment, especially in patients with eGFR in the range 60-90 mL/min/1.73m² or slightly reduced kidney function (stage 3a CKD) and those aged >75 years and is necessary for the future implementation of the Kidney Failure Risk Equation.

Adoption of the Kidney Failure Risk Equation | UK Kidney Association

What’s Changing?

• New Calculation Equation: The eGFR values will now be based on the CKD-EPI 2009 equation, which has been shown to more accurately reflect kidney function compared with the  MDRD equation, particularly in patients with GFR levels >60 mL/min/1.73 m².
• Greater Accuracy at Higher eGFRs: CKD-EPI is designed to minimize underestimation of GFR in patients with less advanced CKD, providing a more accurate basis for decision-making regarding CKD staging and management.
• Impact on eGFR Reporting: For some patients, this change may result in a slight adjustment in reported eGFR values. Any change is expected to be less than 10%. This could impact CKD staging in borderline cases.
• eGFR results will have the following appended from go-live

Note from 28/04/2025 the eGFR calculation has been updated in line with national guidance. There may be some minor changes in the results.

Why This Matters

CKD-EPI’s improved accuracy means:

• Improved Classification of  CKD: Particularly in individuals with normal or near-normal GFR.
• Reduction of Misclassification: Helping avoid potential over-diagnosis of CKD and unnecessary treatments or monitoring in patients with reduced GFR.

Clinical Implications

• Graphing Function: The graph in EMIS will no longer be able to show the trend from old eGFR results which used the MDRD calculation. However, the CEG APL-Renal tool does include a trend graph that includes both eGFR calculations and which can be used instead.
• Patient Discussions: Some patients may notice changes in their eGFR values due to this equation update. It’s essential to reassure them that this does not necessarily indicate a change in their health status but rather a refinement in measurement.
• CKD Diagnosis and Staging:  CKD staging may change especially for those patients with an eGFR near to a boundary.

Quick Reminders for Clinical Practice

• Use Creatinine and eGFR Trends: Continue to interpret eGFR alongside other clinical factors, including creatinine levels and albuminuria. As above, you can use the CEG APL-Renal tool to review the trend, alongside other key clinical information in one place.
• Unexpected Change in eGFR: The serum creatinine assay is NOT changing. If the change in eGFR is greater than expected, then review serum creatinine for any significant change. If serum creatinine is stable, the eGFR change will be due to the change in eGFR calculation.
• Patient Education: When discussing kidney health, emphasize the consistency of their kidney function over time rather than focusing on a single eGFR value.
• CKD Risk Stratification The updated eGFR values are designed to assist in more accurately identifying patients at risk for progression, guiding both preventative and therapeutic strategies.

Urine Albumin: Remember that CKD staging requires a random urine albumin/creatinine ratio measurement (ACR).

Kidney Failure Risk Equation calculations: we do not expect a manifest or significant change in risk of end stage kidney disease prediction using this tool at either 2 or 5 years based on consultations with UK experts.

For  queries:

Clinical renal advice: please contact your usual renal team

Clinical laboratory advice: Duty Biochemist 020 7377 7000 bleep 1611 or 07821 666732 or bhnt.clinbiochemadvice-barts@nhs.net

Information prepared by:

Dr Chris Carvalho, GP, NEL ICB Associate Clinical Director for LTCs.

Dr Anne Dawnay, Clinical Biochemistry, ESEL hosted by Barts Health

Dr Gavin Dreyer, Dept of Renal Medicine, Barts Health

Dr Kieran McCafferty, Dept of Renal Medicine, Barts Health

Dr Payam Torabi, GP, GP, Tower Hamlets LTC Clinical Lead (NEL ICB)

Dr Rina Vaid NEL Diagnostics interim lead

3^rd April 2025