New Model for Estimating Glomerular Filtration Rate in Patients With Cancer

Abstract

<jats:sec><jats:title>Purpose</jats:title><jats:p> The glomerular filtration rate (GFR) is essential for carboplatin chemotherapy dosing; however, the best method to estimate GFR in patients with cancer is unknown. We identify the most accurate and least biased method. </jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p> We obtained data on age, sex, height, weight, serum creatinine concentrations, and results for GFR from chromium-51 (<jats:sup>51</jats:sup>Cr) EDTA excretion measurements (<jats:sup>51</jats:sup>Cr-EDTA GFR) from white patients ≥ 18 years of age with histologically confirmed cancer diagnoses at the Cambridge University Hospital NHS Trust, United Kingdom. We developed a new multivariable linear model for GFR using statistical regression analysis. <jats:sup>51</jats:sup>Cr-EDTA GFR was compared with the estimated GFR (eGFR) from seven published models and our new model, using the statistics root-mean-squared-error (RMSE) and median residual and on an internal and external validation data set. We performed a comparison of carboplatin dosing accuracy on the basis of an absolute percentage error &gt; 20%. </jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p> Between August 2006 and January 2013, data from 2,471 patients were obtained. The new model improved the eGFR accuracy (RMSE, 15.00 mL/min; 95% CI, 14.12 to 16.00 mL/min) compared with all published models. Body surface area (BSA)–adjusted chronic kidney disease epidemiology (CKD-EPI) was the most accurate published model for eGFR (RMSE, 16.30 mL/min; 95% CI, 15.34 to 17.38 mL/min) for the internal validation set. Importantly, the new model reduced the fraction of patients with a carboplatin dose absolute percentage error &gt; 20% to 14.17% in contrast to 18.62% for the BSA-adjusted CKD-EPI and 25.51% for the Cockcroft-Gault formula. The results were externally validated. </jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p> In a large data set from patients with cancer, BSA-adjusted CKD-EPI is the most accurate published model to predict GFR. The new model improves this estimation and may present a new standard of care. </jats:p></jats:sec>