Fewer Black patients will be left unaware of their true kidney function status if their healthcare providers switch to a diagnostic test that doesn’t rely on a race variable, according to a new report by leading kidney care organizations.
The authors urge clinicians to adopt a diagnostic equation that uses a blood test called cystatin C to replace the current equation that relies on serum (blood) creatinine levels.
The new approach will lessen the risk of kidney disease misdiagnosis for Black patients, who experience kidney failure at three times the rate of whites, the National Kidney Foundation said Thursday in announcing the recommendations. It could also alter the diagnosed stage of kidney diseases in some people, it said.
Currently, clinicians use estimated glomerular filtration rate, or eGFR to ascertain kidney function. The test measures creatinine levels in the blood, but the calculations must account for self-reported race in order to give more valid results.
The new recommendation is based on an exhaustive study of alternative approaches for the estimation of GFR, said investigators from the National Kidney Foundation and the American Society of Nephrology Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Diseases.
“Our research showed that if you use a blood cystatin C test, instead of a blood creatinine test, you don’t need to include race to get a similarly accurate estimate of kidney function,” said the study’s co-senior author, Alan S. Go, M.D., of Kaiser Permanente, said in a statement.
“Our results show that race and genetic ancestry are linked to a person’s creatinine level, and we can’t erase that even if we account for a wide range of other factors, such as muscle mass, dietary protein intake, and other factors that are believed to influence blood creatinine level independent of kidney function,” said Dr. Go. “We believe that changing to the cystatin C test will promote more equity for people of all racial and ethnic backgrounds.”
New equation may yield new results
“Patients and healthcare professionals can use a patient-friendly eGFR calculator that uses the new equation to determine a non-race-based calculation to assess their kidney function,” the NKF stated. “It is important for patients to speak with their doctors to determine if this may affect their treatment and care going forward.”
“Using race as a testing factor risks kidney disease misdiagnosis. There is great variance within the genetic ancestry of people who identify as Black which means we cannot reliably view Black people as being from a single ancestral group,” said Afshin Parsa, M.D., of the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases. “Misdiagnosis could lead to a person receiving incorrect drug dosing, or delays in receiving dialysis or a kidney transplant.”
The final report was drafted with input from hundreds of patients, their families and a variety of healthcare providers, scientists and other stakeholders to achieve consensus on the final recommendations, according to the NKF.