New model for estimating glomerular filtration rate in patients with cancer results improves accuracy of carboplatin chemotherapy dosing
Session type: Proffered paper sessions
Theme: Diagnosis and therapy
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.(1)
We obtained data on age, sex, height, weight, serum creatinine concentrations, and results for GFR from chromium-51 (51Cr) EDTA excretion measurements (51Cr-EDTA GFR) from white adult patients 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. 51Cr-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 also performed a comparison of carboplatin chemotherapy dosing accuracy.
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 CKD-EPI was the most accurate published model for eGFR (RMSE, 16.30 mL/min; 95% CI, 15.34 to 17.38 mL/min). Importantly, the new model reduced the fraction of patients with a carboplatin dose absolute percentage error > 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. The online tool for our model has had 1200 unique users in the first 6 weeks since online publication.
The new model improves this estimation and may present a new standard of care. Further improvements can be achieved with purpose build models that investigate best dose calculations for specific indications, such as adjuvant treatment of patients with seminoma. 1) Janowitz and Williams et al., doi:10.1200/JCO.2017.72.7578