Height-Independent Estimation of Glomerular Filtration Rate in Children: An Alternative to the Schwartz Equation

ObjectiveTo compare the diagnostic performance of 2 height-independent equations used to calculate estimated glomerular filtration rate (eGFR), those of Pottel (eGFR-Pottel) and the British Columbia Children's Hospital (BCCH) (eGFR-BCCH), with the commonly used Schwartz equation (eGFR-Schwartz).Study designWe externally validated eGFR-Pottel and eGFR-BCCH in a well-characterized pediatric patient population (n = 152) and compared their diagnostic performance with that of eGFR-Schwartz using Bland-Altman analysis. All patients underwent glomerular filtration rate measurement using the gold standard single-injection inulin clearance method (GFR-inulin).ResultsMedian GFR-inulin was 92.0 mL/min/1.73 m² (IQR, 76.1-107.4 mL/min/1.73 m²). Compared with GFR-inulin, the mean bias for eGFR-Schwartz was −10.1 mL/min/1.73 m2 (95% limits of agreement [LOA], −77.5 to 57.2 mL/min/1.73 m2), compared with −12.3 mL/min/1.73 m² (95% LOA, −72.6 to 47.9 mL/min/1.73 m2) for eGFR-Pottel and −22.1 mL/min/1.73 m² (95% LOA, −105.0 to 60.8 mL/min/1.73 m2) for eGFR-BCCH. eGFR-Pottel showed comparable accuracy to eGFR-Schwartz, with 77% and 76% of estimates within 30% of GFR-inulin, respectively. eGFR-BCCH was less accurate than eGFR-Schwartz (66% of estimates within 30% of GFR-inulin; P < .01).ConclusionThe performance of eGFR-Pottel is superior to that of eGFR-BCCH and comparable with that of eGFR-Schwartz. eGFR-Pottel is a valid alternative to eGFR-Schwartz in children and could be reported by the laboratory if height data are not available.