166 Does the Use of Intrawound Vancomycin Decrease the Risk of Surgical Site Infection After Elective Spine Surgery?—A Multicenter Analysis. (August 2015) - Devin, Clinton J.
Abstract : INTRODUCTION: Surgical site infection (SSI) is an expensive complication associated with spine surgery. The application of intrawound vancomycin is rapidly emerging as a solution to reduce SSI. The impact of intrawound vancomycin has not been systematically studied in a well-designed multicenter study. We determine whether intrawound vancomycin application was associated with reduced risk of SSI in patients after spine surgery. METHODS: Patients undergoing elective spine surgery over the period of 4 years at 7 different sites across the United States were included in the study. Patients were given standard IV antibiotics perioperatively and dichotomized based on whether intrawound vancomycin was applied. Multivariable random-effects log-binomial regression analyses were conducted to determine the relative-risk of having a SSI and a SSI with return to the operating room (OR) within postoperative 30 days. Random effects was included a priori to account for clustering of patients within each site. Fraction of variance attributable to differences between sites was calculated by dividing the variance of site random effect by the total variance in the model (site + participants). RESULTS: Two thousand three hundred eleven patients were included: degenerative spine pathologies 89% (2056), trauma 10% (233), and tumor 1% (22) (Table 1). Intrawound vancomycin was used in 45% of patients. Prevalence of SSI was 5.1% in the absence of vancomycin use vs 2.4% with intrawound vancomycin. Site-to-site variation in SSI ranged from 1.5% to 5.7% (Table 2). In multivariable regression model, patients in whom intrawound vancomycin was not used (RR 2.3, CI 1.5-3.6), those with higher number of levels exposed (RR 1.1, CI 1.0-1.1), postoperative ICU admission (RR 2.1, CI 1.3-3.3), and obesity (RR 1.8, CI 1.0-3.0) had higher risk of developing SSI. Risk factors for SSI with return to OR included: not applying intrawound vancomycin (RR 5.2, CI 2.6-10.4), higher number of levels exposed (RR 1.1, CI 1.0-1.2), and postoperative ICU admission (RR 2.5, CI 1.5-4.3). Geographical site variation accounted for 3% of variance in SSI and 20% in SSI with return to the OR. CONCLUSION: Intrawound application of vancomycin after elective spine surgery was associated with reduced risk of SSI and return to OR associated with SSI, even after controlling for confounding variables.