Abstract
Therapeutic drug monitoring (TDM) of blood concentrations is recommended in treatment with vancomycin (VCM). The relationship between the clinical effects of VCM and PK/PD parameters, however, has still not been sufficiently clarified and few studies on PK/PD parameters in elderly patients have been performed to date. In this study, PK parameters correlating with clinical efficacy were determined using a two-compartment Bayesian model in 63 elderly patients with methicillin-resistant Staphylococcus aureus (MRSA) infection who were treated with VCM. This was done through comparison of a VCM-effective group (39 patients) and a non-effective group (24 patients) using logistic regression analysis. Blood trough level [odds-ratio=1.150, 95% confidence interval=1.012-1.307, P=0.0323] and AUC [odds-ratio=1.011, 95% confidence interval=1.005-1.017, P=0.0004] were identified as factors correlating with clinical efficacy. In receiver operating characteristic (ROC) curve analysis, the optimal cutoff values of the AUC and blood trough level were determined to be as follows-AUC : 420μg/mL · hr (sensitivity : 69.2% ; specificity : 79.2%), blood trough level : 10μg/mL (sensitivity : 66.7% ; specificity : 66.7%).
In conclusion, our results suggest that VCM exhibits a clinical effect in elderly patients infected with MRSA at blood trough levels of≥10μg/mL or an AUC of≥420μg/mL · hr. It is therefore necessary to determine the therapeutic course for VCM in consideration of AUC as well as the blood trough level.
