Methodology · 6 min read
CKD-EPI 2021 vs 2009 — why the formula changed.
If you've seen two different eGFR numbers from the same creatinine, or a calculator that asks for race, this is why. In 2021 the standard equation for estimating kidney function was rebuilt to remove race as an input. Here's what changed and why it matters.
Last updated April 15, 2026.
The 2009 equation and its race coefficient
The original CKD-EPI equation, published in 2009, included a multiplier of about 1.159 for patients recorded as Black. The statistical rationale at the time was that Black participants in the development dataset had slightly higher average creatinine, presumed to reflect higher muscle mass. The practical consequence was that Black patients were assigned a highereGFR for the exact same creatinine value — which could delay referral to nephrology, transplant waitlisting, and dose adjustments for kidney-cleared drugs.
Why it was replaced
Race is a social and political category, not a biological variable that filters blood. A joint task force of the National Kidney Foundation and the American Society of Nephrology reviewed the evidence and, in 2021, recommended immediate adoption of a new race-free equation. The replacement, published by Inker and colleagues in the New England Journal of Medicine, was refit so it performs comparably across populations without using race at all.
The 2021 race-free formula
The 2021 creatinine equation estimates eGFR from creatinine, age, and sex:
κ = 0.7 (female) or 0.9 (male) · α = −0.241 (female) or −0.302 (male) · Scr in mg/dL
Notice there is no race term anywhere in it. If a tool asks you to select a race to compute eGFR, it is running the obsolete 2009 equation.
What it means for your result
- For most people, the number barely moves. For patients who were previously given the race multiplier, the 2021 equation typically reports a modestly lower eGFR — which can mean earlier, more appropriate recognition of kidney disease.
- It's one consistent number for everyone. The same creatinine, age, and sex now produce the same eGFR regardless of race.
- Cystatin C adds precision when needed. When a confirmatory estimate matters — at the extremes of muscle mass, for example — a combined creatinine–cystatin C equation is more accurate.
Frequently asked questions
What is the difference between CKD-EPI 2009 and 2021?+
The 2009 CKD-EPI equation included a race coefficient that multiplied eGFR by about 1.16 for patients recorded as Black. The 2021 equation removes race entirely and re-fits the other variables, so it estimates eGFR from creatinine, age, and sex alone. The 2021 version is the current US standard.
Why was the race coefficient removed?+
Race is a social construct, not a biological measure of kidney function. The 2009 coefficient assigned Black patients a higher eGFR for the same creatinine, which could delay specialist referral, transplant listing, and medication adjustments. A joint NKF–ASN task force recommended a race-free equation in 2021.
Which equation should my lab be using?+
Most US laboratories have adopted the CKD-EPI 2021 creatinine equation. If a calculator or lab still asks you for race, it is using the older 2009 equation. The race-free 2021 version is endorsed by the National Kidney Foundation and the American Society of Nephrology.
Did removing race make eGFR less accurate?+
No. The 2021 equation was developed and validated to perform comparably across populations without using race. For greater precision in selected cases, a combined creatinine–cystatin C equation (CKD-EPI 2021 cr-cys) is even more accurate and is recommended when a confirmatory estimate is needed.
Our calculator uses the race-free CKD-EPI 2021 equation described above.
For general education only. Not medical advice or a diagnosis. Reference: Inker LA, Eneanya ND, Coresh J, et al. New creatinine- and cystatin C-based equations to estimate GFR without race. N Engl J Med. 2021;385(19):1737-1749. Delgado C, et al. A unifying approach for GFR estimation: recommendations of the NKF-ASN Task Force. 2021.