Discrepancy between predicted and measured GFR in hospitalized Nigerian children

Current clinical guidelines for the management of chronic kidney disease recommend the use of prediction equations for determination of glomerular filtration rate (GFR). Our aim was to determine the accuracy of the Schwartz and the modified Counahan-Barratt equations in predicting GFR in hospitalized Nigerian children. We compared GFR as estimated by the Schwartz and the Counahan-Barratt equations against endogenous creatinine clearance (Ccr) in 90 hospitalized Nigerian children of varying renal function. The bias (i.e. the mean difference) in GFR estimation by the Schwartz and the modified Counahan-Barratt equations in relation to Ccr were 16.7 and 21.5, respectively. The predicted GFR values correlated poorly with the measured Ccr (-0.19 and -0.18 for Schwartz and Counahan-Barratt equations respectively). The positive predictive value of the Schwartz and Counahan-Barratt equations to detect GFR <60 ml/min were 9.8% and 11.9% respectively. These equations do not provide reliable estimates of the GFR when compared to Ccr in Nigerian sick children and hence can not replace Ccr in clinical practice. Further studies are needed to develop reliable alternatives for Ccr in these children.