How to predict carboplatin clearance from standard morphological and biological charactersties in obese patients

Abstract

Background: We previously proposed a formula to predict carboplatin clearance (CL) from four patient characteristics: plasma creatinine level, body weight, age. and sex (j Natl Cancer Inst 1995: 87: 573). Its accuracy was studied in a subpopulation of obese patients. Patients and methods: Twenty-five paiiems (16 male and 9 female, 23 to 82 years old) were studied. They were 20% to 67% (median 36%) over the ideal weight which was calculated according to the Lorentz equation. Their actual CL was obtained individually by the Siphar program. The pharmaco-kinetic population program NONMEM was used to determine the best value of substitution for weight in the formula. Results: By using the actual weight, CL was significantly overpredicted (by more than 20% for 7 of 25 patients). By using the mean value between the ideal and the actual weight, a good prediction of CL was obtained: the percentage of error ranged from -21% to +22%. Conclusion: The formula is applicable to obese patients if both ideal and actual weights are taken into account. © 1997 Kluwer Academic Publishers.