Response

Extract

Minami et al. further point out the importance of the method used for creatinine measurement in relation to individualized dosing of carboplatin. Although Minami et al. point out that the Cockcroft-Gault equation was based on the original Jaffé method, Cockcroft et al. ( 1 ) stated that they measured serum and urine creatinine concentrations using a N-11B autoanalyzer (Technicon Instruments Corp., Tarrytown, NY); the autoanalyzer method used the Jaffé reaction, but separated creatinine from noncreatinine chromogens by their differential rates of color development ( 2 , 3 ). As shown in Fig. 1, A , we were unable to improve the mean prediction error (MPE) and root mean square error (RMSE) for our patient population ( 4 ) when we adjusted the Calvert formula using the Cockcroft-Gault-predicted creatinine clearance value by replacing serum creatinine (mg/dL) with (serum creatinine + 0.2 mg/dL), as suggested by Minami et al. Although Chatelut et al. ( 5 ) pointed out the discrepancy between our results and those obtained by Calvert et al. ( 6 ) and van Warmerdam et al. ( 7 ), we feel unable to comment on the discrepancy because the method used for creatinine measurement was not reported by Calvert et al., and also because the instrument used by van Warmerdam et al. (CX5CE Synchron Clinical System instrument; Beckman Instruments, Inc., Fullerton, CA) was different from ours. On the other hand, it is noteworthy that we were able to improve the prediction result when we adjusted the Chatelut formula, as suggested by Minami et al. ( Fig. 1, B ).