1260. Comparative Effectiveness of Vancomycin versus Vancomycin plus Beta-Lactams for Prevention of Surgical Site Infections
Session: Oral Abstract Session: Device and Procedure Related HAIs
Friday, October 9, 2015: 2:00 PM
Room: 32--ABC
Background: The optimal regimen for pre-operative antibiotic prophylaxis is controversial. Prior studies suggest that beta-lactam antibiotics (BLA) are superior to vancomycin (vanco) for preventing surgical site infections (SSI), however, whether there is an additional benefit to adding a BLA to vanco remains unknown. Thus, we sought to evaluate the comparative effectiveness of vanco versus vanco plus BLA for SSI prevention.

Methods: All patients who underwent surgery within the national VA health care system during the period from 10/1/08-9/30/13, received vanco, and had SSI outcomes and prophylaxis manually validated were included. Primary outcome was incidence of SSI among patients receiving vanco versus vanco plus BLA. Secondary analysis evaluated SSI incidence stratified by types of surgical procedures. Known confounders were included in the multivariable logistic regression (Table 1).

Results: 20,056 unique procedures were included. 33.6% (6603/20,056) received  vanco only and 66.4% (13,324/20,056) received vanco plus BL. Among patients receiving vanco only, the SSI incidence was 1.9% (129/6,732) versus 1.3% (177/13,324) among patients receiving vanco plus BLA, a 31.6% reduction, p<0.0001.  Among cardiac procedures, the incidence of SSI was 0.80% (25/3,137) in the vanco group versus 0.42% (31/7,337) in the vanco plus BLA group, a 47.5% reduction, p=0.00014. There was no difference in SSI outcome among other types of surgical procedures, including total joint replacements. Adjusted results are presented in Table 1.

Conclusion: Adding a BLA to vanco for peri-operative SSI prevention significantly reduces the incidence of SSI, independent of ASA class and MRSA-colonization status; the association is strongest for cardiac surgical procedures.  Further analysis of effect modifiers and confounders, including other MRSA-targeted prevention strategies, need to be investigated.

Table 1. Adjusted Model for SSI Risk in Patients Receiving Vancomycin vs Vancomycin plus a Beta-Lactam Antibiotic.

Variable

Odds Ratio (95% CI)

P-Value

Vanco & BLA vs Vanco

0.965 (0.943-0.988)

0.0026

ASA Class

1.43 (1.22-1.69)

<0.0001

MRSA positive

2.71 (1.99-3.68)

<0.0001

Age (per year)

1.01 (0.997-1.02)

0.154

Westyn Branch-Elliman, MD, MMSc, Medicine, University of Colorado, Aurora, CO; Division of Infectious Diseases, Denver VA Medical Center, Denver, CO, Judith Strymish, MD, Harvard Medical School, Boston, MA; Infectious Disease, VA Boston Healthcare System, West Roxbury, MA, Marin Schweizer, PhD, Department of Medicine, University of Iowa Carver College of Medicine, Iowa City, IA; Center for Comprehensive Access and Delivery Research and Evaluation (CADRE), Iowa City VA Health Care System, Iowa City, IA, Kamal Itani, MD, Department of Surgery, VA Boston and Boston University School of Medicine, West Roxbury, MA, Michael Ho, MD, PhD, Medicine, Denver VA Medical Center, Denver, CO; University of Colorado School of Medicine, Denver, CO and Kalpana Gupta, MD, MPH, Department of Medicine/Boston University School of Medicine, Boston, MA

Disclosures:

W. Branch-Elliman, None

J. Strymish, None

M. Schweizer, None

K. Itani, Sanofi: Investigator , Grant recipient

M. Ho, None

K. Gupta, None

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