CKD-EPI 2009

Chronic Kidney Disease Epidemiology Collaboration

Creatinine-based equation for adults with a Black race coefficient

Biomarkers: Creatinine
Validated for: 18+ years
Inputs: Age, Sex, Creatinine (optional: Race)
Reports: mL/min/1.73 m²
Published: 2009

The eGFR guide explains which equation the calculator suggests and indexed and absolute GFR.

Formula

\text{eGFR} = 141 \times \min(S_{cr}/\kappa, 1)^{\alpha} \times \max(S_{cr}/\kappa, 1)^{-1.209} \times 0.993^{\text{age}} \times \text{sex factor} \times \text{race factor}

As text: eGFR = 141 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^(-1.209) × 0.993^age × sex × race

Constants

Symbol	Meaning	Value
`141`	Base coefficient
$\kappa$	Sex-dependent creatinine coefficient	Female: 0.7mg/dL Male: 0.9mg/dL
$\alpha$	Exponent when SCr/κ < 1	Female: −0.329 Male: −0.411
`−1.209`	Exponent when SCr/κ ≥ 1
`0.993`	Age decay factor (base for age exponent)	per year
`Sex factor`	Sex-dependent multiplier	Female: 1.018 Male: 1.000
`Race factor`	Race-dependent multiplier	Black: 1.159 Other: 1.000
$S_{cr}$	Serum creatinine (input)	mg/dL
`Age`	Patient age (input)	years

How it was developed

Developed in 8,254 participants pooled from 10 studies (6 research studies and 4 clinical populations), with GFR measured as urinary iothalamate clearance; the final coefficients were fitted on the development (5,504) and internal validation (2,750) sets combined. External validation used 3,896 participants from 16 other studies.

Clinical notes

Built on creatinine recalibrated to the standardized Roche enzymatic assay
Refitted without the race term as CKD-EPI 2021

Limitations

Few participants with higher GFR, older than 70, or non-Black minorities
Age, sex and race do not explain all non-GFR creatinine variation
Incomplete data on muscle mass and medications affecting creatinine independent of GFR

References

Levey AS, Stevens LA, Schmid CH, et al. A new equation to estimate glomerular filtration rate. Ann Intern Med. 2009;150(9):604-612. doi:10.7326/0003-4819-150-9-200905050-00006
Stevens LA, Claybon MA, Schmid CH, et al. Evaluation of the Chronic Kidney Disease Epidemiology Collaboration equation for estimating the glomerular filtration rate in multiple ethnicities. Kidney Int. 2011;79(5):555-562. doi:10.1038/ki.2010.462
Delgado C, Baweja M, Crews DC, et al. A unifying approach for GFR estimation: recommendations of the NKF-ASN Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease. J Am Soc Nephrol. 2021;32(12):2994-3015. doi:10.1681/ASN.2021070988