For many years, the universally used equation for estimating risk of kidney disease (the kidney function estimate, Chronic Kidney Disease Epidemiology Collaboration [CKDEPI] equation), included an adjustment for Black race that led to an upward correction in estimated glomerular filtration rate (eGFR). In 2021, new equations that omit race but include other factors were developed and found to be more accurate in estimating eGFR, (1) and the US National Kidney Foundation, American Society of Nephrology Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Diseases and the UK National Institute for Health and Care Excellence recommended the removal of race from the calculation of eGFR. (2,3) We discuss why the inclusion of race in kidney function estimates is biased and harmful, and why swift adoption of calculations that omit race is important in clinical care in Canada.
In the United States and Canada, Black people have a higher incidence of chronic kidney disease (CKD), have more rapid kidney disease progression, are referred later for kidney care, are less likely to receive home-based dialysis or a kidney transplant, and have higher mortality after kidney transplantation. (4,5) Calculations of eGFR using the Black "race correction," which have been widely used in Canada, can falsely increase eGFR up to 10%, which can lead to delayed diagnosis and thus poorer outcomes. (1)
The global prevalence of kidney disease is 8%-16%. (6) Early disease is often asymptomatic and, therefore, missed, which is why methods were developed to improve screening, to identify people at risk earlier and to allow referral for appropriate care to prevent disease advancement. Application and widespread use of equations to estimate kidney function were a major advance in addressing kidney disease in clinical practice. The eGFR is automatically calculated with serum creatinine and reported by many laboratories throughout Canada. The widespread adoption of eGFR reporting in Ontario and British Columbia led to a 2%-6% increase in use of medications that slow the progression of CKD. (7) In tandem, rates of referral to nephrology rose to 24%, the equivalent of 23 new consults per nephrologist per year in Ontario. (8) Automatic reporting of kidney function enables clinical interpretation while raising awareness of kidney disease for both patients and providers.
Serum creatinine is a constituent of muscle protein metabolism, linked to protein intake, intrinsic muscle mass and kidney function. Serum creatinine estimates were widely believed to be less accurate in people of Black race and were hypothesized to be due to higher muscle mass on average. Whether or not this is true remains controversial. (9) Estimating equations of kidney function using serum creatinine were developed and incorporated a correction factor for Black race with the goal of improving scientific measurement and accuracy. As data on race are not routinely collected by health systems in Canada, laboratories have reported kidney function estimates without race correction, and the decision to apply the race adjustment was left to the judgment of clinicians.
As race adjustment inflates the CKD-EPI eGFR measurements in Black people,...