NKF-ASN task force outlines challenges with GFR measurement and race
An interim report by a National Kidney Foundation-American Society of Nephrology task force outlines challenges on the use of race in estimating GFR and suggests methods to evaluate new approaches to using it as a kidney function measure.
Estimation of GFR is a “major underpinning of many clinical decisions in medicine,” the task force members wrote in the report, which was published concurrently in the American Journal of Kidney Diseases and the Journal of the American Society of Nephrology. “The use of race to estimate GFR and possible replacements have shortcomings that the task force is currently examining. Nationwide, many institutions have made independent decisions to address race in estimation of GFR, but these approaches vary and, therefore, GFR estimates and subsequent care decisions are not standardized,” they wrote.
“Because these differing approaches may have varying effects for patients treated and followed by clinicians — including but not limited to primary care physicians, medical specialists (eg, nephrologists, hospitalists, endocrinologists, cardiologists, oncologists), surgical specialists, pharmacists and public-health professionals — the task force would like to offer a careful and judicious review to guide implementation efforts for a standardized and equitable approach to care.”
The final report by the task force is expected to include recommendations on new techniques to measure GFR.
In the paper, the authors cite the importance of measuring creatinine to estimate kidney function as eGFR, writing “it has served as a major marker” for the diagnosis of kidney diseases and as a measure in determining other courses of treatment.
“Creatinine-based eGFR thresholds guide clinical practice, including estimation of surgical complication risk; initiation, discontinuation and dosing of medications; and utilization of certain contrast-based tests and procedures, such as computed tomography scans or cardiac catheterizations,” Cynthia Delgado, MD, and colleagues wrote.
Most clinical laboratories in the United States report eGFR with a metabolic panel that contains serum creatinine. Separate estimates are given for African American patients. “... [S]ome regard keeping a race term in GFR equations as a practice that differentially influences access to care and kidney transplantation,” the authors wrote. “Others assert that race captures important GFR determinants and its removal from the calculation may perpetuate other disparities.”
The task force organized activities into three main steps, that included the following:
- clarifying the problem and examine evidence about the use of GFR;
- evaluate different approaches to address use of race in GFR estimation; and
- make recommendations to the kidney community.
The task force members note that removing race from the eGFR equation “is not trivial ... the downstream consequences of changes from current reporting are unknown and could be profound,” they wrote. “Changes could lead to overdiagnosis or underdiagnosis of kidney diseases as a result of GFR estimation bias and inaccuracy for any ethnic group. Conclusive evidence on outcomes from well-conducted studies will likely take years to produce.
“The resultant effects in terms of the numbers of African Americans affected and the safety and effectiveness of pharmacotherapy use and dosing need appraisal,” they wrote.
“Additionally, effect on managing risk factors (eg, hypertension), nephrology referral, transplant waitlisting and kidney donation will also warrant evaluation.”
Likewise, the ramifications of changes in eGFR equations on research studies examining kidney diseases in African American patients and in patients of other races/ethnicities would have to be examined, along with how such changes might affect FDA approval and labeling of therapies. “The availability in communities of assays for newer, raceless biomarkers (eg, cystatin C, b-trace protein, b2 microglobulin) also need evaluation,” the task force members wrote.