Are there inequalities in kidney health?
Disparities for kidney disease have been recognized for decades in the U.S. Of the more than 37 million American adults affected by kidney diseases, a disproportionate number are of African American, Hispanic, Asian, and Native American descent. African Americans are three times more likely than Non-Hispanic Whites to experience kidney failure. Such disparities go beyond the high prevalence of kidney diseases and extend into differences in treatment modality, including access to kidney transplantation. While African Americans represent 35% of people receiving dialysis in the United States, they are less likely to be identified as kidney transplant candidates compared to Non-Hispanic Whites.
What is the controversy over using race in measuring eGFR?
Measured GFR is the best way to report kidney function, but this is too complicated for routine medical care. Race is used to estimate glomerular filtration rate (eGFR), which is based on a blood test that checks how well the kidneys are working. Age and sex are also used with race to estimate GFR. Studies have suggested that using race can make the eGFR more accurate compared to the true most accurate measured GFR. However, the use of race in measuring eGFR has been a subject of debate. Race is not a biological concept, but a social concept. Using race in calculating eGFR does not account for the diversity within communities of color. Also, people who identify as multiracial might not want to be put in a single category of race.
Why is eGFR used?
The eGFR is one of the main tests for diagnosing kidney disease. This test is reported by almost all medical laboratories not only in the United States but worldwide. The eGFR informs healthcare professionals about kidney function that helps the healthcare team plan treatments. If the eGFR number is low that can mean the kidneys are not working as well as they should. The earlier kidney disease is detected, the better the chance of managing it or keeping it from getting worse. This test is used in many important decisions for treatment and management, such as the following:
- 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 entry or exclusion criterion
- Making sure the right type of imaging test and dye 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
How is race used in estimating GFR?
The eGFR is calculated from the amount of creatinine in the blood using a math equation. Creatinine is a waste product that comes from the normal wear and tear on muscles of the body and also from the diet. Everyone has creatinine in their bloodstream. However, different people can have different creatinine levels in their blood. This difference is not always related to kidney disease, and it can be affected by different factors, such as age, sex, body weight and/or race. Several equations have been created to measure eGFR using a combination of these factors with the goal of getting a more accurate measure of kidney function.
Studies have shown that individuals who self-identify as Black or African Americans can have higher levels of creatinine in the blood (on average), compared to people of other races or ethnicities. However, otherwise similar Black and White Americans can have the same blood creatinine level, but also have different eGFRs for reasons that can include differences in muscle mass, differences in diet and differences in the way the kidneys eliminate creatinine.
What is the NKF doing to address concerns about using race in measuring eGFR?
The National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) formed a joint task force to review the use of race in measuring eGFR.
This task force will look for a better way to account for different levels of creatinine between people other than race. The task force will also make sure that eGFR provides an unbiased measurement of how well the kidneys are working. The ultimate goal is to make sure that racial bias does not affect the diagnosis and treatment of kidney disease.
Although the NKF alone cannot solve all inequalities, the NKF is working to help identify, confront and reverse them. NKF advocates for making affordable healthcare more available and making sure that communities of color are not left behind. NKF’s CARES helpline is available to all people with kidney disease regardless of who they are. NKF’s educational offerings include the impact of kidney disease on diverse communities, and why COVID-19 has had more of an impact on communities of color. NKF is committed to continuing its work to address inequalities in kidney health.