Objectives: To quantify the direct medical costs associated with using vancomycin, as inpatient treatment, in methicillin-resistant Staphylococcus aureus infections, in four clinical indications: complicated skin and soft tissue infections (SSTI), bacteremia, infective endocarditis (IE), and hospital-acquired pneumonia (HAP).
Research design and methods: A decision-analytic model was constructed to evaluate the cost of administering intravenous vancomycin. Cost inputs included hospitalization, drug procurement, materials, preparation and administration, renal function and drug monitoring, treating adverse events, and treatment failure. Probabilities and lengths of stay and treatment were obtained from the literature, an antimicrobial therapy database and clinical expert opinion. Univariate and multivariate sensitivity analyses were conducted to confirm the robustness of the baseline scenario.
Main outcome measures: The cost of using vancomycin in the four indications, including and excluding hospital cost.
Results: Whereas the drug acquisition price of vancomycin 1g is US dollars 9.01 per dose, when all costs associated with using vancomycin were included, the cost per dose rose to US dollars 29-US dollars 43 per patient. Total costs per patient receiving multiple doses in a single course of treatment, excluding hospital room costs, were for SSTI, bacteremia, IE, and HAP,US dollars 779, US dollars 749, US dollars 2261, and US dollars 768, respectively. Total costs, including hospital length of stay, were for SSTI US dollars 23616, bacteremia US dollars 26446, IE US dollars 48925, and HAP US dollars 22493. In univariate analyses varying per diem hospital costs and length of stay had the greatest impact. Results of the multivariate analysis were comparable to the costs in the baseline scenario for all indications.
Conclusions: This analysis highlights the importance of capturing all costs associated with using a drug and not simply focusing on drug acquisition cost. Future economic analyses should identify and account for the key cost burdens of a particular treatment to calculate its true cost.