A comparison of measured and estimated glomerular filtration rate for carboplatin dose calculation in stage I testicular seminoma.

UNLABELLED: Dose calculation of adjuvant carboplatin chemotherapy for stage I testicular seminoma, based on area under the concentration curve (AUC), incorporates the glomerular filtration rate (GFR). This retrospective study compares 'gold standard' (51)Cr-ethylenediamine tetraacetic acid ((51)Cr-EDTA) GFR measurements with renal function estimations derived from the Cockcroft-Gault, Jelliffe and Wright formulae. INCLUSION CRITERIA: stage I testicular seminoma treated with a single dose of carboplatin AUC7 at one centre in South Wales, UK, between 2005 and 2011, with contemporaneous (51)Cr-EDTA GFR measurement and serum creatinine. Renal function estimates obtained using Cockcroft-Gault, Jelliffe and Wright formulae were analysed for bias (mean percentage error, MPE) and precision (mean absolute percentage error, MAPE) compared to the gold standard. Sixty-eight patients were identified, median age 40 (range 17-66), median creatinine 82 (range 55-120). For the Cockcroft-Gault, Jelliffe and Wright formulae, respectively, MPE was +12.4, -32.3 and +8.8; MAPE was 16.0, 32.7 and 12.9; and substitution of the calculated GFR result for (51)Cr-EDTA measurement would have resulted in a >10% discrepancy in carboplatin dose in 41.1, 97.1 and 42.6% of patients (predominantly overdoses for the Cockcroft-Gault and Wright formulae, underdoses for the Jelliffe formula). Of the formulae analysed, none accurately correlated with (51)Cr-EDTA GFR measurements.