Ann Lab Med.  2019 Mar;39(2):205-208. 10.3343/alm.2019.39.2.205.

Estimated Glomerular Filtration Rates Show Minor but Significant Differences Between the Single and Subgroup Creatinine-Based Chronic Kidney Disease Epidemiology Collaboration Equations

• Park S
• Jeong TD

• KMID: 2425977
• DOI: http://doi.org/10.3343/alm.2019.39.2.205

Abstract

The creatinine-based Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation can be calculated according to race, sex, and creatinine concentration (subgroup equation) or in the form expressed by one equation (single equation). Minor differences in the constants used in the CKD-EPI equations (subgroup vs single equations) could result in a significant difference in the estimated glomerular filtration rate (eGFR). We evaluated the impact of this difference in 79,709 Korean patients. The eGFR was calculated as an integer using the single and subgroup CKD-EPI equations. The differences in eGFR and GFR categories between the equations were analyzed. eGFR was higher in the subgroup equation than the single equation by 1 mL/min/1.73 m² for 12,476 (27.4%) Korean females. The GFR category based on the subgroup equation was reclassified using the single equation for 352 (0.77%) females. Based on the results, the constant of the single equation was optimized. There was no difference in eGFR values between equations using a multiplier of 1.0213 instead of 1.018 for the "white or other" females constant in the single CKD-EPI equation. Clinicians should carefully apply the CKD-EPI equation because eGFR values may differ by 1 mL/min/1.73 m² depending on the manner of calculation. To minimize these differences, the constants of the single equation should be revised.

Keyword

Creatinine-based Chronic Kidney Disease Epidemiology Collaboration equation; Constant modification; Glomerular filtration rate

MeSH Terms

Continental Population Groups
Cooperative Behavior*
Creatinine
Epidemiology*
Female
Glomerular Filtration Rate*
Humans
Renal Insufficiency, Chronic*
Creatinine

Figure

• 

  Fig. 1 Distribution of GFR category according to the creatinine-based CKD-EPI equation in females. The overall agreement between the subgroup and single equations was 99.2% (weighted kappa, 0.990; 95% confidence interval, 0.989–0.991). (A) When using the single equation with the constant 1.018, the GFR categories of 352 (0.77%, 352/45,560) patients were reclassified. (B) The use of 1.0213 rather than 1.018 eliminated the difference in eGFR. *GFR=141×min (Scr/κ, 1)α×max (Scr/κ, 1)−1.209×(0.993)Age×1.018 [if female]×1.159 [if black]; †GFR=141×min (Scr/κ, 1)α×max (Scr/κ, 1)−1.209×(0.993)Age×1.0213 [if female]×1.159 [if black].Abbreviations: CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration; eGFR, estimated glomerular filtration rate; G1, ≥90; G2, 60–89; G3a, 45–59; G3b, 30–44; G4, 15–29; G5,<15 mL/min/1.73 m2; GFR, glomerular filtration rate.

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