Excluding patient race when estimating GFR may lead to error
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Eliminating race from equations estimating GFR was associated with error and underestimation, primarily for African American patients, according to a research letter.
“Glomerular filtration rate (GFR) is critically important for determining drug dosing as well as prognosis and treatment in patients with kidney disease,” Andrew S. Levey, MD, of Tufts Medical Center in Boston, and colleagues wrote. “Despite its importance, we rarely measure it directly. Instead, we use serum creatinine level to estimate GFR (eGFRcr). Because serum creatinine is determined by diet and muscle mass, as well as GFR, we use age, sex, race (African American vs. non-African American), height or weight to adjust the estimation of GFR.”
Noting that race is a social construct rather than a factor rooted in biology (and because some patients are of mixed race), they suggested using race when estimating GFR could present problems and inaccuracies. Researchers estimated GFR with equations that included or excluded patient race (n = 8,254; 31.5% were African American), and compared these estimates to measured GFR (mGFR) values that used urinary clearance of iothalamate and serum creatinine “traceable to an international reference standard.”
They found eliminating the race coefficient was associated with systematic error and an underestimation of mGFR. The performance of equations not using race was worse for African American patients and adding height and weight did not lead to improvements.
Therefore, the researchers expressed concern that excluding race from estimations of GFR may present “unintended consequences” for African American patients, including inappropriate early transplant or dialysis initiation, overdiagnosis of chronic kidney disease and errors in prescribing/dosing of medications.
“Better methods are needed to improve the accuracy of GFR assessment without requiring specification of race,” they argued. – by Melissa J. Webb
Disclosure: Levey reports grants and contracts from NIH and NKF to Tufts Medical Center, as well as a clinical trial contract with AstraZeneca.
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