Comparison of carboplatin doses according to several formulae in a cohort of patients treated for an ovarian cancer in real life

Abstract

Introduction

Carboplatin doses are calculated using several formulae, with the most recent being the Calvert formula with Glomerular Filtration Rate estimated using the CKD Epi cystatin C (Calvert CKD-Epi Cys) equation. The aim of this study was to compare the carboplatin doses estimated by this formula with the most commonly used formulas.

Materials and methods

The carboplatin doses prescribed for 84 patients with ovarian cancer were calculated according to Chatelut, Calvert with Glomerular Filtration Rate estimated using Cockcroft and Gault (Calvert CG), CKD-Epi (Calvert CKD-Epi) equation, modified Thomas and Calvert CKD-Epi Cys formulas. First, these 4 formulas were compared with the Calvert CKD-Epi Cys formula using a Wilcoxon test for pairwise comparison, and by assessing mean predictive error (MPE), mean absolute percentage error (MAPE), and absolute percentage error over 20% (P20). A subgroup analysis was then performed to determine the clinical and biological parameters responsible for the observed differences.

Results

Thomas modified formulas showed low bias (MPE = 1.5%) and good precision (MAPE = 4.5%). Chatelut and Calvert CG were less precise with P20 values of32.1% and 13.5% respectively. Differences were mostly due to body weight, age and plasma cystatin C levels. The Calvert CKD-Epi formula showed good precision (MAPE = 8.1%) and low bias (MPE = 2.4%) except when plasma cystatin C levels were equal or above normal range (MPE = 14.9%).

Conclusion

As proposed by White-Koning et al., we have chosen Calvert CKD-Epi Cys formula as a reference for carboplatin dosage calculations in our hospital. However, the limited doses differences with the Calvert CKD-Epi formula make it another reliable option in clinical practice.