Justine B. Bukabau1,7, Eric Yayo2,7, Appolinaire Gnionsahe´ 3, Dagui Monnet2, Hans Pottel4, Etienne Cavalier5, Aliocha Nkodila1, Jean Robert R. Makulo1, Vieux M. Mokoli1, Franc¸ois B. Lepira1, Nazaire M. Nseka1, Jean-Marie Krzesinski6, Ernest K. Sumaili1,7 and Pierre Delanaye6,7

1Renal Unit, Department of Internal Medicine, Kinshasa University Hospital, University of Kinshasa, Kinshasa, Democratic Republic of  Congo; 2Département de Biochimie, UFR Sciences Pharmaceutiques et Biologiques, Université Felix Houphouet Boigny, Abidjan, Ivory Coast; 3Département de Néphrologie, UFR Sciences Médicales, Université Felix Houphouet Boigny, Abidjan, Ivory Coast; 4Department of Public Health and Primary Care, KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium; 5Division of Clinical Chemistry, CHU Sart Tilman (ULg CHU), University of Liège, Liège, Belgium; and 6Division of Nephrology-Dialysis-Transplantation, CHU Sart Tilman (ULg CHU), University of Liège, Liège, Belgium

Glomerular filtration rate (GFR) is the best index for kidney function; however, the applicability of GFR estimating equations in sub-Saharan African populations remains unclear. In a cross-sectional study of adults living in Kinshasa, Democratic Republic of Congo (n[210) and Abidjan, Ivory Coast (n[284), we evaluated the performance of creatinine and cystatin C–based equations using plasma clearance of iohexol as the reference standard. The race coefficient did not improve the performance of creatinine-based GFR estimates; in fact, both the Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology (CKD-EPI) equations
performed better without the race coefficient in participants with GFR ‡60 mL/min/1.73m2. The CKD-EPI and Full Age Spectrum (FAS) equations were unbiased and
had similar precision (SD of 17.9 versus 19 mL/min/1.73 m2) and accuracy within 30% (P30, 86.7% versus 87.4%) in participants with GFR ‡60 mL/min/1.73m2. Both equations performed poorly in the subgroup with measured GFR < 60 mL/min/1.73m2 (n[80), but the FAS equation had smaller bias (L4.8 mL/min/1.73m2 versus L7.7 mL/min/1.73m2 for CKD-EPI) and higher P30 (56.3% versus 31.3% for CKD-EPI).
The corresponding equations including cystatin C alone or in combination with creatinine had similar performance. In a sub-Saharan African population, adjustment for race did not improve the performance of GFR estimating equations.
The creatinine-based FAS and CKD-EPI equations performed reasonably well and were comparable when GFR was ‡ 60 mL/min/1.73m2. Cystatin C did not improve
performance. The FAS equation may be preferable when GFR is < 60 mL/min/1.73m2, but this should be confirmed in larger studies.
Kidney International (2019) 95, 1181–1189; https://doi.org/10.1016/ j.kint.2018.11.045

KEYWORDS: creatinine; cystatin C; glomerular filtration rate; iohexol; sub-Saharan Africa
Copyright ª 2019, International Society of Nephrology. Published by Elsevier Inc. All rights reserved.