Background: A vancomycin target of area under the curve to minimum inhibitory concentration (AUC:MIC) ratio ≥400 is recommended for treatment of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. Objective: To evaluate vancomycin total daily dose (TDD) achieving trough targets versus a calculated strategy achieving AUC targets based on body mass index (BMI). Methods: A retrospective cohort study was performed within a large hospital network. Patients with MRSA bacteremia were eligible if they received vancomycin with a steady-state trough (15-20 mg/L). Cockcroft-Gault was used to estimate creatinine clearance, calculating vancomycin clearance and AUC. Patients were stratified by BMI (less than/greater than 30 kg/m2). The primary outcome was vancomycin TDD for the trough-based strategy compared with an AUC-dosing strategy. Results: A total of 119 patients were included, including 51 (42.9%) and 68 (57.1%) patients with high- and low-BMI, respectively. The TDD for trough-based dosing (2390.76 ± 1224.59 mg) differed significantly from AUC-based dosing (1985.07 ± 616.18 mg) across the cohort (P = 0.0014). For patients with high BMI, there was a significant difference (P < 0.0001) in TDD between trough (2637.25 ± 1327.89 mg) versus AUC (1918.71 ± 625.89 mg) strategies. No difference in TDD between dosing strategies was observed among low-BMI patients. Across all patients, 46 (38.7%) experienced acute kidney injury (AKI); high-BMI patients experienced higher rates of AKI compared with low-BMI patients (54.9 vs 26.5%; P = 0.002). Conclusions and Relevance: An AUC-based dosing strategy may reduce vancomycin TDD required for MRSA bacteremia compared with trough-based dosing, particularly for patients with higher BMI.
Keywords: obesity; therapeutic drug monitoring; vancomycin.