Short CommunicationEstimation of the Initial Dose Setting of Vancomycin Therapy With Use of Cystatin C as a New Marker of Renal FunctionTanaka, Akihiro*; Suemaru, Katsuya PhD*; Otsuka, Takashi†; Ido, Keiko*; Nishimiya, Tatsuya‡; Sakai, Ikuya MD§; Hasegawa, Hitoshi MD§; Inoue, Tomoyoshi†; Murase, Mitsuharu‡; Yasukawa, Masaki MD§; Araki, Hiroaki PhD*Author Information From the *Division of Pharmacy, Ehime University Hospital; †Department of Hospital Pharmacy, Matsuyama Shimin Hospital; ‡Division of Laboratory Medicine; and §First Department of Internal Medicine, Ehime University School of Medicine, Ehime, Japan. Received for publication May 19, 2006; accepted January 8, 2007. Correspondence: Katsuya Suemaru, PhD, Division of Pharmacy, Ehime University Hospital, 454 Shitsukawa, Toon, Ehime, 791-0295 Japan (e-mail: [email protected]). Therapeutic Drug Monitoring: April 2007 - Volume 29 - Issue 2 - p 261-264 doi: 10.1097/FTD.0b013e31803bcfd2 Buy Metrics Abstract In recent years, it has been suggested that the glomerular filtration rate (GFR) can be predicted on the basis of serum cystatin C concentrations and that this measurement is more sensitive than serum creatinine concentration as a marker of renal function. In this study, to investigate the clinical utility of the initial dose setting of vancomycin by the population mean method with use of serum cystatin C as a marker of renal function, we compared the correlations between measured vancomycin concentrations and predicted vancomycin concentrations based on serum cystatin C or serum creatinine concentrations in elderly (≥65 years old) and nonelderly (<65 years old) patients. An analysis of prediction accuracy (bias) and precision was evaluated by calculating the mean prediction error (ME), the mean absolute error (MAE), and the root mean squared prediction error (RMSE). For nonelderly patients (n = 50), there was no significant difference in the MAE based on the use of serum creatinine or serum cystatin C concentration. However, for elderly patients (n = 105), the MAE based on serum cystatin C concentration was significantly better than that based on serum creatinine level. These results suggest that serum cystatin C is a good marker of renal function in comparison with serum creatinine for dose setting of vancomycin, especially in an elderly population. © 2007 Lippincott Williams & Wilkins, Inc.