Evaluation of glomerular filtration rate estimation by Cockcroft-Gault, Jelliffe, Wright and Modification of Diet in Renal Disease (MDRD) formulae in oncology patients

The aim was to evaluate the accuracy of Cockcroft-Gault, Jelliffe, Wright and Modification of Diet in Renal Disease (MDRD) formulae as a substitute for the gold standard measure of glomerular filtration rate (GFR) using chromium 51 EDTA. Retrospective analysis of GFR measurements in oncology patients from a University Teaching Hospital over 3 years was carried out. Bias and precision of estimates of GFR were compared with measured GFR. Six hundred and sixty patients with measured GFR (median 90 ml/min, range 23-179 ml/min) were identified. Cockcroft-Gault produced the smallest bias (median percentage error -1.4%) and highest precision (median absolute percentage error 14.0%) and was the most accurate for carboplatin dosing. For patients > 30% over their ideal body weight (IBW), using IBW + 30% in the Cockcroft-Gault formula was more precise than using actual body weight or IBW. The Wright formula was most accurate for patients aged 70 + years and patients with a body mass index (BMI) >= 30 but overestimated GFR when GFR < 50 ml/min. When measured GFR is unavailable, we advise estimating GFR using the Cockcroft-Gault formula and using IBW + 30% for patients weighing > 30% over their IBW. If the GFR is >= 50 ml/min and the patient is > 70 years and/or BMI >= 30, the Wright formula gives the best estimate of GFR.