The New eGFR Calculation

traumaRUs, MSN, APRN

In 2020 research began to circulate that using a different calculation for determining eGFR or estimated glomerular filtration rate with adjustment for race was incorrect and led to much inequity in many realms of care. The Cleveland Clinic tells us that the eGFR measures the output of your glomeruli (filters of the kidneys for waste products). It is measured in ml/min and is the amount of waste products that your kidneys remove.

Until fairly recently, eGFR was adjusted upwards for African Americans. Why was race factored into this calculation? From the National Kidney Foundation:

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Race was originally included in eGFR calculations because clinical trials demonstrated that people who self-identify as Black/African American can have, on average, higher levels of creatinine in their blood. It was thought the reason why was due to differences in muscle mass, diet, and the way the kidneys eliminate creatinine.

This led to African Americans not being wait-listed for transplant until later in the course of their chronic kidney disease. Also, African American patients were not being referred as early to specialized nephrology care as their White counterparts. This caused a greater number of African American patients to go on to develop end-stage renal disease.

Calculating the eGFR has many variables. The National Institute of Diabetes and Digestive and Kidney Disorders recommends using the National Kidney Foundation's eGFR calculator. Here is the newest (2023) calculator for eGFR without factoring in race.

According to the National Kidney Foundation the eGFR is used in a variety of ways for many decisions made in patient care:

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Confirming that kidney function is normal for a potential living kidney donor

Making sure the right dose of medicine is used

Enrollment in clinical trials that use kidney function as an inclusion or exclusion criterion

Making sure the right type of imaging tests and dyes are used

When to refer someone to a nephrologist or kidney doctor

If and when to plan for dialysis

When to start an evaluation for a kidney transplant

By looking at the ways that eGFR is used in patient care, you can readily understand why an accurate eGFR is mandatory. For instance:

It's vitally important that a potential living kidney donor has excellent renal function. If eGFR is overestimated, the living donor could unwittingly donate a kidney and then experience decline in his own renal function.
Many medications must be renally dosed. Medications can cause potentially fatal consequences, especially when you overestimate eGFR. Some of the more common medications which can be problematic include anti-virals, antibiotics, BP meds
Clinical trials should be representative of a population. In the US, our population is a melting pot of races, so it is important for research that all races be included
eGFR must be factored in when ordering contrast studies. Dose reduction is an important consideration when ordering radiological tests.
All patients with an eGFR >30ml/min should be under the care of a nephrologist.
Dialysis or renal replacement therapy is what end-stage renal disease patients face. The earlier it is determined that renal replacement therapy will be needed, the better. This allows for pre-emptive placement of a permanent access and modality consideration.
One of the biggest influences on the new calculation for eGFR is consideration for renal transplant.

Renal transplant consideration based on race-predictive eGFR came to a screeching halt in 2022 when the Organ Procurement and Transplantation Network (OPTN) passed this policy:

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Effective July 27, transplant hospitals are prohibited from using eGFR calculations that include a race-based variable in OPTN policy.

All transplant hospitals should take steps to understand what calculations they or their associated labs currently use to estimate GFR, and what actions they need to take to comply with these changes.

This has positively affected transplant rates for African American patients. In the US, the two main disease processes that bring patients to a nephrologist's office are hypertension and diabetes. Both of these are often found in the African American population. By adjusting the eGFR and eliminating race as a factor, all patients face a more even playing field.

What do you think? Have you seen or know of patients where re-calculation of eGFR has resulted in a change of care? Does your hospital still use race as a factor in eGFR?

References/Resources

Estimated Glomerular Filtration Rate (eGFR) : Cleveland Clinic

Recommended eGFR Calculators: National Institute of Diabetes, Digestive and Kidney Disorders

Understanding African American and non-African American eGFR laboratory results: National Kidney Foundation

Implementation notice: Requirement for race neutral eGFR formulas in effect: United Network for Organ Sharing

The New eGFR Calculation

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