Multi-institutional validation study of carboplatin dosing formula using adjusted serum creatinine level

Area of Science:

• Oncology
• Pharmacokinetics
• Clinical Chemistry

Background:

• Creatinine clearance (Ccr) is a surrogate for glomerular filtration rate (GFR) in carboplatin dosing.
• The standard Calvert formula leads to overdosing when serum creatinine is measured using the enzymatic peroxidase-antiperoxidase method (PAP-Cr).

Purpose of the Study:

• To prospectively validate an amended carboplatin dosing formula that adjusts for PAP-Cr measurements.
• To assess the accuracy and precision of the amended formula compared to the standard Calvert formula.

Main Methods:

• Prospective validation of an amended carboplatin dosing formula in 55 patients across six institutions.
• Carboplatin clearance estimation using the amended formula with adjusted PAP-Cr versus the standard Calvert formula.
• Comparison of mean prediction error (MPE) and root mean squared error (RMSE) between formulas.

Main Results:

• The amended formula provided unbiased (MPE +/- SE = 2.9 +/- 3.4%) and precise (RMSE = 24.7%) carboplatin clearance estimation.
• The standard Calvert formula systematically overpredicted carboplatin clearance (MPE +/- SE = 24.9 +/- 4.9%, RMSE = 36.1%).
• Adjusting PAP-Cr improved accuracy for the Chatelut formula as well.

Conclusions:

• Adjusting serum PAP-Cr is essential for accurate carboplatin dosing.
• The amended formula significantly reduces bias and improves precision in carboplatin dose calculations.
• This adjustment is vital for optimizing chemotherapy regimens and patient outcomes.