1415. Implementation and Validation of a Vancomycin AUC/MIC Calculator and Dosing Protocol at a Large Community Hospital

Background Current IDSA guidelines recommend targeting a vancomycin trough between 15 and 20 mg/L to achieve an AUC/MIC ≥ 400; however, recent literature shows increased rates of nephrotoxicity within this range and the target AUC/MIC ratio may be achieved with lower troughs. We sought to determine whether a vancomycin AUC-based dosing protocol and spreadsheet-based calculator, using one-compartment population-based dosing and two steady-state serum levels, accurately predicted AUC/MIC ratio in patients with moderate to severe Staphylococcus aureus infections. Methods A retrospective analysis of 60 adult patients treated with vancomycin for culture-confirmed S. aureus was conducted. The primary outcome was percent of patients who met the AUC/MIC goal of ≥400. Secondary outcomes included: mean initial trough concentration in patients who met the AUC/MIC goal compared with those who did not; correlation of two different methods of AUC-estimation with the patient’s actual AUC; percentage of patients meeting AUC/MIC goal stratified by initial trough concentrations, age, weight, and indication; and percentage of patients meeting the AUC goal stratified by the same variables. Results were analyzed using descriptive statistics and calculations were performed using SPSS. Results The median age (range) was 55 (22–86) and 52% were male. Eighty-three percent of patients achieved an initial AUC/MIC ≥ 400, including 93% with serum troughs between 10 and 14.9 mg/L. Patients who met the AUC/MIC goal had an average trough of 13.5 mg/L, whereas those who did not had an average trough of 7.8 mg/L (P < 0.001). AUC estimation using population pharmacokinetics was significantly correlated with actual AUC (P = 0.011); however, this was not a strong correlation (r = 0.340). Subgroup analysis based on age, weight, and indication identified areas for improvement in the empiric dosing protocol at our institution. Conclusion Use of the vancomycin AUC-based dosing protocol and calculator resulted in achievement of efficacy goal in the majority of patients, including many with vancomycin troughs between 10 and 15 mg/L. More accurate estimation of AUC and other pharmacokinetic variables using local patient data is important for improving the reliability of vancomycin dosing protocols. Disclosures All authors: No reported disclosures.