Implementation of Weight-Based Antimicrobial Dosing for Surgical Site Infection Prophylaxis

Surgical site infections (SSIs) increase morbidity, mortality, and health care costs. Morbid obesity has been identified as an independent risk factor; it has been demonstrated that higher doses of antimicrobials are warranted to achieve adequate tissue concentrations. In 2008, the University of Michigan Health System (UMHS) implemented weight-based dosing such that patients with a documented weight of ≥80 kg would receive a larger initial dose of antibiotic for surgical prophylaxis. This process included a pharmacy dose optimization program provided by an operating room pharmacy where pharmacists could automatically increase the dose based on weight if the initial order was noncompliant with institutional guidelines. The objectives of the study were to assess rates of compliance with the guidelines prior to and after implementation. This study was a retrospective evaluation of SSI prophylaxis dosing in obese patients prior to (April through June 2008) and after (September through November 2008) implementation of a dose optimization program. After implementation, there was a 29.7% increase in weight-based antibiotic surgical prophylaxis; pharmacy intervention accounted for 15% of the change. The implementation of a dose optimization program could prove to be cost-effective by ensuring patients receive the correct weight-based antibiotic and by perhaps reducing the incidence of SSIs.