Intra-wound vancomycin and tobramycin powder for infection prophylaxis in orthopaedic trauma surgery: Economically justifiable?

Objectives: There is increasing interest regarding the risks and benefits of intrawound antibiotics applied directly to surgical wounds for the prevention of infection following orthopaedic trauma surgery. The purpose of this study was to investigate the economic justifiability of vancomycin and tobramycin powders for infection prophylaxis in orthopaedic trauma surgery. Methods: The cost of vancomycin and tobramycin powders, infection rates and costs of treating surgical site infections were obtained from our institution's records and existing literature. A break-even analysis was then performed using vancomycin powder only, tobramycin powder only and combined vancomycin and tobramycin powders to determine the respective absolute risk reduction (ARR) in infection rate needed to make the prophylactic application of each therapy type break-even. Results: At our institutional pricing of $20.64 and $75.80 for 1g vancomycin and 1.2g tobramycin, respectively, use of each individually would be economically justified if it reduced an average infection rate of 4.3% by an ARR of 0.02% and 0.07%, respectively. Used in combination for $90.66, the ARR was 0.09%. Varying cost of treating infection from $5,000-$200,000 while maintaining cost of antibiotic powder at $90.66 demonstrated a range in ARR from 1.93% to 0.05%, respectively. At the same cost of $90.66 but varying infection rate from 1% to 25% did not affect ARR, which was constant at 0.09%. Conclusions: Considering the cost of vancomycin and tobramycin powder at our institution, the application of these powders, whether independently or in combination, appear to be economically justifiable for infection prevention in orthopaedic trauma surgery.