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Estimated glomerular filtration rate: applicability of creatinine-based equations in African children
Agathe Bikupe Nkoy1,2, Therance Tobo Matoka3, Justine Busanga Bukabau4
1Division of Nephrology, Department of Pediatrics, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of Congo. agath.nkoy@gmail.com.
Insights
The Schwartz equation
Area of Science:
- Pediatric Nephrology
- Clinical Chemistry
- Epidemiology
Background:
- The Schwartz equation is a standard for estimating glomerular filtration rate (GFR) using serum creatinine (SCr) in European children.
- Its applicability to African children remains uncertain, necessitating further investigation.
Purpose of the Study:
- To evaluate the performance of commonly used estimated GFR (eGFR) equations in African children.
- To determine if SCr normalization and reference intervals for European children are suitable for African populations.
Main Methods:
- A cross-sectional study of 513 healthy African children (aged 6-16 years) in the Democratic Republic of Congo.
- Serum creatinine measured enzymatically and normalized using Q-values for European descent children.
- Application and comparison of various eGFR equations, including Schwartz, FAS-Age, CKiDU25, EKFC, LMR18, FAS-Height, and Schwartz-Lyon.
Main Results:
- Normalization of SCr using European Q-values was effective, with 93.4% of African children falling within the reference interval.
- The FAS-Age formula demonstrated no significant age or sex dependency, outperforming other equations.
- Several equations, including bedside-Schwartz, showed significant age and/or sex dependency.
Conclusions:
- The reference interval for SCr established for European children is applicable to African children.
- The FAS-Age equation is the most suitable for estimating GFR in this population due to its independence from age and sex, and lack of height requirement.
- Developing specific Q-values for Jaffe-measured creatinine in Africa could enhance the applicability of these estimations.
Background:
The Schwartz equation is the most widely used serum creatinine (SCr)-based formula to estimate the glomerular filtration rate (GFR) in children of European descent, but whether this applies to African children is unclear.
Methods:
In a cross-sectional study, 513 apparently healthy African children aged 6 to 16 years were randomly recruited in school area of Kinshasa, the Democratic Republic of Congo (DRC). SCr was measured using calibrated enzymatic method. SCr was normalized using Q-values designed for European descent children, due to the absence of Q-values for African children. Commonly used eGFR equations were applied in this population.
Results:
Normalization of SCr using Q-values for European descent children was effective in this cohort. The majority of African children (93.4%) have normalized SCr (SCr/Q) values within the reference interval (0.67-1.33) of children of European descent. The bedside-Schwartz equation was associated with significant age and sex dependency. However, the FAS-Age formula showed no sex and age dependency. The new CKiDU25 equation did not show a significant sex dependency. The recently introduced EKFC and LMR18 equations also showed no age and sex dependency, although the distribution of eGFR-values was not symmetrical. On the other hand, the FAS-Height and the Schwartz-Lyon equations showed significant sex dependency but no age dependency.
Conclusions:
The reference interval for SCr designed for European descent children can be applied to African children. Of all the equations studied, FAS-Age performed best and is most suitable because no height measurements are required. Establishment of specific Q-values for the widespread Jaffe-measured creatinine in Africa can further broaden applicability.
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