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Published on: May 10, 2013
Development and Validation of a Modified Full Age Spectrum Creatinine-Based Equation to Estimate Glomerular
Hans Pottel1, Jonas Björk2, Marie Courbebaisse3
1KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium (H.P.).
Insights
A new European Kidney Function Consortium (EKFC) equation improves glomerular filtration rate (GFR) estimation in children and adults. This updated formula offers greater accuracy and precision than existing serum creatinine (SCr)-based methods.
Area of Science:
- Nephrology
- Pediatric Nephrology
- Clinical Chemistry
Background:
- Current serum creatinine (SCr)-based equations for estimating glomerular filtration rate (GFR), including the Chronic Kidney Disease in Children Study (CKiD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations, have limitations.
- These limitations include implausible GFR changes during adolescence to adulthood transitions and GFR overestimation in young adults. The Full Age Spectrum (FAS) equation, while addressing some issues, overestimates GFR at low SCr levels.
Purpose of the Study:
- To develop and validate a modified FAS SCr-based equation that integrates design features from both FAS and CKD-EPI equations.
- To improve the accuracy and precision of GFR estimation across a wide age range and SCr levels.
Main Methods:
- A cross-sectional analysis using pooled data from 13 research and clinical studies (11,251 participants for development/internal validation, 8378 for external validation).
- Development of a new equation using measured GFR (exogenous marker clearance), SCr levels, age, sex, and height.
- Validation of the new equation against existing methods using separate datasets.
Main Results:
- The newly developed European Kidney Function Consortium (EKFC) equation demonstrated low bias across the full age spectrum (2-90 years) and SCr range.
- The EKFC equation showed fewer estimation errors exceeding 30% compared to CKiD and CKD-EPI equations in both children (6.5%) and adults (3.1%).
- The EKFC equation exhibited improved accuracy and precision in estimating GFR from SCr levels.
Conclusions:
- The European Kidney Function Consortium (EKFC) equation represents a significant advancement in GFR estimation from serum creatinine.
- This new equation offers improved accuracy and precision, addressing limitations of previous models, particularly across the full age spectrum.
- The EKFC equation is recommended for clinical use in estimating GFR in both pediatric and adult populations.
Background:
The Chronic Kidney Disease in Children Study (CKiD) equation for children and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation for adults are recommended serum creatinine (SCr)-based calculations for estimating glomerular filtration rate (GFR). However, these equations, as well as their combination, have limitations, notably the problem of implausible changes in GFR during the transition from adolescence to adulthood and overestimation of GFR in young adults. The full age spectrum (FAS) equation addresses these issues but overestimates GFR when SCr levels are low.
Objective:
To develop and validate a modified FAS SCr-based equation combining design features of the FAS and CKD-EPI equations.
Design:
Cross-sectional analysis with separate pooled data sets for development and validation.
Setting:
Research and clinical studies (n = 13) with measured GFR available.
Patients:
11 251 participants in 7 studies (development and internal validation data sets) and 8378 participants in 6 studies (external validation data set).
Measurements:
Clearance of an exogenous marker (reference method), SCr level, age, sex, and height were used to develop a new equation to estimate GFR.
Results:
The new European Kidney Function Consortium (EKFC) equation is a FAS equation with low bias (-1.2 mL/min/1.73 m2 [95% CI, -2.7 to 0.0 mL/min/1.73 m2] in children and -0.9 mL/min/1.73 m2 [CI, -1.2 to -0.5 mL/min/1.73 m2] in adults) across the FAS (2 to 90 years) and SCr range (40 to 490 µmol/L [0.45 to 5.54 mg/dL]) and with fewer estimation errors exceeding 30% (6.5% [CI, 3.8% to 9.1%] in children and 3.1% [CI, 2.5% to 3.6%] in adults) compared with the CKiD and CKD-EPI equations.
Limitation:
No Black patients were included.
Conclusion:
The new EKFC equation shows improved accuracy and precision compared with commonly used equations for estimating GFR from SCr levels.
Primary Funding Source:
Swedish Research Council (Vetenskapsrådet).
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