505. Optimizing Vancomycin Dosing for Peri-operative Prophylaxis in High-risk Orthopedic Surgery Patients: Time for A Change
Session: Poster Abstract Session: Surgical Site Infections
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Posters
  • IDSA2013PosterOrthoVancoDosing.pdf (541.1 kB)
  • Background:

    Since 2008 all patients at our institution undergoing arthroplasty and spine fusion are screened for Staphylococcus aureus nasal colonization and vancomycin (VAN) is added if methicillin-resistant S. aureus (MRSA) detected. Optimal vancomycin (VAN) timing and dose prior to surgery in MRSA colonized patients is critical to minimize post-operative surgical site infections (PSSI). We assessed potential benefits of VAN weight-based (WB) dosing as compared to VAN 1 g dose in these high-risk patients.

    Methods:

    We included patients with positive MRSA nasal screen and arthroplasty or spine fusion performed between January 2009 and January 2012. All patients received VAN 1 g within 1 hour prior to incision. VAN WB dose (15 mg/kg of actual body weight [ABW] rounded to the nearest 250 mg, maximum 2 g) was calculated for each patient. Patients were classified as underdosed (calculated WB dose >1 g dose) or overdosed (calculated WB dose <1 g dose). We used pharmacokinetic formulas to estimate VAN levels at the time of wound closure based on duration of procedure (optime). Percent of patients with predicted VAN levels <10 mg/L and <15 mg/L at the time of wound closure were compared for each dosing regimen.

    Results:

    Among 216 patients, 68% underwent arthroplasty (knee n=75, hip n=66, shoulder n=6), 24% spine fusion and 8% laminectomy. Median optime was 124 (29-470) min.  Mean age was 60 years, ABW was 86 kg (68% of patients had ABW >20% of ideal BW) and creatinine clearance was 79 mL/min. Mean VAN dose and half-life were 12 mg/kg and 10 h respectively. VAN 1 g dose was appropriate in 21% of patients, 10% were overdosed by 250 mg and 69% were underdosed (44% by 250 mg, 32% by 500 mg, 17% by 750 mg, 7% by 1000 mg). Predicted VAN level at the end of procedure was <10 mg/L in 9% of patients with 1 g dose compared to 2% if WB dose was used, P=.0002. Predicted VAN level at the end of procedure was <15 mg/L in 60% of patients with 1 g dose compared to 12% with WB dose, P=.0005. Nine patients developed PSSI, and 6/9 had positive cultures with MRSA (4/6 VAN MIC of 1 mg/L). These 6 patients with MRSA PSSI were underdosed with VAN 1 g dose and 5/6 had predicted level <15 mg/L at the time of wound closure.

    Conclusion:

    VAN WB dosing will provide higher rate of adequate levels at the time of wound closure. Our surgical prophylaxis guidelines have been changed to recommend VAN WB dosing.

    Yanina Dubrovskaya, PharmD1, Joseph Bosco III, MD2, Anthony Catanzano, Medical Student3, Lorraine Hutzler, BA2, Donald Chen, MD4, Anna Stachel, MPH5, Michael S. Phillips, MD4 and Marco R. Scipione, PharmD1, (1)Department of Pharmacy, NYU Langone Medical Center, New York, NY, (2)Orthopedic Surgery, NYU Hospital for Joint Diseases, New York, NY, (3)NYU Langone Medical Center, New York, NY, (4)Infection Prevention and Control, NYU Langone Medical Center, New York, NY, (5)Infection Prevention and Control, New York University Langone Medical Center, New York, NY

    Disclosures:

    Y. Dubrovskaya, None

    J. Bosco III, None

    A. Catanzano, None

    L. Hutzler, None

    D. Chen, None

    A. Stachel, None

    M. S. Phillips, None

    M. R. Scipione, None

    Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 2nd with the exception of research findings presented at the IDWeek press conferences.