Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2023

A comparison of carboplatin dosing between Cockcroft-Gault equation versus BSA-adjusted eGFRCKD-EPI equation  (#213)

Neil Lam 1 , Ian Kei Yee 2 , Linda Nguyen 1
  1. Icon Wesley Pharmacy, Icon Cancer Centre , Brisbane, QLD, Australia
  2. School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia

Aims

Carboplatin dosing, based on the Calvert Formula, requires the patient’s glomerular filtration rate (GFR) in its calculation. Historically, the Cockcroft-Gault equation was used to determine estimated GFR (eGFR), by calculating creatinine clearance. However, the recently introduced International Consensus Guideline for Anticancer Drug Dosing in Kidney Dysfunction (ADDIKD) recommend the Chronic Kidney Dysfunction-Epidemiology Collaboration 2009 equation (eGFRCKD-EPI) to replace the Cockcroft-Gault (CG) equation in determining eGFR. This study aimed to compare the carboplatin dose variations between Cockcroft-Gault and BSA (body surface area)-adjusted eGFRCKD-EPI equations.

Method

A retrospective audit of initial carboplatin doses (n=127) administered between January and December 2022 at a day oncology clinic was conducted. Patient parameters included age, sex, weight, height, serum creatinine and target AUC (area under the curve). Carboplatin doses were calculated using both CG and BSA-adjusted eGFRCKD-EPI equations. Statistical analysis was performed using the paired t-test. The Pearson correlation coefficient was calculated to investigate the relationship between patient parameters and percentage dose variation.

Results

70.9% of doses (90/127) had ≤10% dose variation between the CG and BSA-adjusted eGFRCKD-EPI method. 23.6% of doses (30/127) had a >10% to ≤20% dose variation. The mean dose difference between the two methods did not reach statistical significance (p=0.06). There was a weak correlation between weight and percentage variation (r=-0.39) with a trend suggesting that extremes in body weight resulted in larger percentage dose variation. 

Conclusion

In this study, the majority of doses calculated using the BSA-adjusted eGFRCKD-EPI method were within 20% compared to the CG method. The mean dose difference did not reach statistical significance. With implementation of the BSA-adjusted eGFRCKD-EPI equation in practice, this may provide some reassurance to clinicians regarding dose variances between the two equations, however further study is required to determine clinical significance.