Performance and Cut-Off of Three Glomerular Filtration Rate Estimation Equations in a Population of Cameroonian Patients with Chronic Kidney Disease Stages 3 - 5 Non Dialyzed

Abstract

Background : Diagnosis of End-stage kidney disease (ESKD) is based on the glomerular filtration rate estimation equation. However, discrepancies have been observed in those formulas for the African population. We evaluated the performance of the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), and Cockcroft-Gault (CG) equations against measured glomerular filtration (mGFR) to diagnose end-stage renal disease in 27 patients with CKD stage 3 - 5. Methods : Consenting non-dialyzed chronic kidney disease patients consulting at the outpatient department in a nephrology referral center in Yaoundé were enrolled. We obtained mGFR from the average of Urea Clearance and Creatinine Clearance. These were obtained from validated 24-hour urine samples. Statistical comparison of the eGFR with measured GFR was performed using Bland-Altman analysis and Kappa statistics. The Receiver Operating Curve (ROC) was used to determine the best cut-off of eGFR to diagnose ESKD. Results : The three equations had a good accuracy for diagnosing ESKD with c-statistics ranging from 0.97 to 0.98. Best cut-offs of eGFR for diagnosis of ESKD were 16.25 ml/min/1.73m 2 for CKD-EPI, 18 ml/min/1.73m 2 for MDRD, and 16.8 ml/min/1.73m 2 for CG. Using these cut-offs, the agreement with mGFR was almost perfect for CKD-EPI (kappa = 0.852) and MDRD (kappa = 0.852), and moderate for CG (kappa = 0.78). Conclusion : The CKD-EPI equation seems to be slightly better than that of MDRD and CG in diagnosing ESKD in sub-Saharan Africans. The improvement of agreement while using a higher cut-off of more than 15 ml/min/1.73m 2 calls for revision for better accuracy.