Which "weigh" to Go? Alternative Vancomycin Dosing Strategies in Obese Patients

Purpose This study aims to compare the performance of alternative weight-based vancomycin dosing strategies to traditional dosing in obese patients using area under the curve (AUC) monitoring. Methods This retrospective study compared target attainment of an AUC between 400-600mcg*H/mL using alternative vancomycin dosing strategies. All patients received allometrically dosed vancomycin, with patient-specific AUCs calculated using 2 post-infusion steady-state vancomycin serum concentrations using the trapezoidal rule. Predicted AUCs were calculated using the following: 15 mg/kg total body weight (TBW), 15 mg/kg corrected body weight (CBW), and 12.5 mg/kg TBW. Predicted AUCs from the traditional 15 mg/kg TBW dosing were then compared to alternative dosing strategies using the predicted AUCs from 12.5 mg/kg TBW, 15 mg/kg CBW, and the actual AUCs calculated using allometrically scaled vancomycin dosing. The primary outcome was attainment of initial AUC within the target range of 400-600mcg*H/mL for each dosing method. Results Eighty-four patients were included. When AUCs were compared to traditional 15 mg/kg dosing strategy, the CBW, 12.5 mg/kg, and allometric dosing strategies were significantly more likely to result in initial attainment of an AUC within a target range of 400-600 mcg*H/mL (P = 0.0003, 0.0135, and 0.0088, respectively). No significant differences were seen between each of the alternative dosing methods (P = 0.73). Conclusion The 3 alternative vancomycin dosing strategies examined were all significantly more likely to achieve an initial AUC within the target range compared to traditional vancomycin dosing in obese patients. Clinicians should strongly consider one of these alternative dosing strategies for obese patients as opposed to traditional vancomycin dosing.