Notice of the change to the equation used to calculate estimate glomerular filtration rate (eGFR) across UHB on November 22nd 2021

On 22.11.201, the formula to calculate eGFR at UHB will be changed from MDRD to CKD-EPI. This is in line with long standing NICE guidance. This is a more accurate equation to estimate GFR. This will not affect the management of patients and should not lead to a major eGFR change on an individual patient basis. As per NICE guidance, it is no longer necessary to correct for ethnicity.

Further information

At present, eGFR is calculated at UHB using the MDRD equation. This equation was based upon measurements in patients with established renal disease. It uses creatinine, sex, age, and the ethnicity of the patient to estimate the GFR.  The group that developed the MDRD equation subsequently developed the CKD-EPI equation using data from patients who had normal and impaired renal function. Like MDRD, the original CKD-EPI equation used creatinine, sex, age, and the ethnicity of the patient to estimate the GFR however recent NICE guidance has recommended that ethnicity is no longer used. CKD-EPI is thought to reflect renal function better than the MDRD equation. Compared to measured GFR, performance of the two equations are similar when GFR is < 60 mL/min/1.73 m² with the MDRD equation underestimating GFR at levels > 60 mL/min/1.73 m² when compared to the CKD-EPI equation. It is thought that the impact on patient management will be minimal however there is a possibility that CKD classifications could change due to CKD-EPI more closely reflecting the ‘true’ GFR. NICE has recommended using the CKD-EPI equation to calculate eGFR since 2014 with ethnicity removal outlined this year.

There is no change to specimen requirements or test requesting.

For clinical queries relating to this change please contact Professor Paul Cockwell (This email address is being protected from spambots. You need JavaScript enabled to view it.). For laboratory queries please contact Dr Alex Lawson (This email address is being protected from spambots. You need JavaScript enabled to view it.).

References

Chronic kidney disease: assessment and management. NICE guideline [NG203]

https://www.nice.org.uk/guidance/ng203/resources/chronic-kidney-disease-assessment-and-management-pdf-66143713055173

UK Kidney Association The rationale for removing adjustment for ethnicity from eGFRcreatinine and recommendations for implementation of the change in practice

https://ukkidney.org/sites/renal.org/files/guidelines/Rationale_and_recommendations_for_implementation_NICE%20CKD%20Guideline%202021.pdf

Original CKD-EPI Paper – Comparison of MDRD and CKD-EPI

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763564/pdf/nihms132246.pdf