The Effect of Local Administration of Vancomycin Suspended in Fibrin Glue for Prevention of Surgical Site Infection After Spinal Instrumentation: Comparison by Probability of Treatment Weighting Model

Abstract

Study Design. A retrospective cohort study. Objective. To compare the surgical site infection (SSI) rate in patients undergoing spinal instrumentation surgery who received vancomycin suspended in fibrin glue at the surgical site and those who did not. Summary of Background Data. The intrawound application of vancomycin powder for preventing SSI after spinal surgery remains controversial. Vancomycin suspended in fibrin glue is another option for local administration that may be effective. The present study assessed whether vancomycin suspended in fibrin glue could prevent SSI after spinal instrumentation surgery. Materials and Methods. We enrolled patients who underwent posterior spinal instrumentation surgery with or without fusion for degenerative conditions, spinal trauma, or tumor. A multiple logistic regression model with inverse probability of treatment weighting based on propensity score was used to assess the efficacy of vancomycin suspended in fibrin glue and to account for confounding. A secondary multivariate logistic regression analysis was performed to identify the risk factors associated with SSI. Results. Of the 264 patients enrolled in this study, 134 underwent application of vancomycin suspended in fibrin glue at the surgical site and 130 did not. The incidence of SSI was lower in patients who were treated with vancomycin suspended in fibrin glue (2.2% vs. 8.5%) even after inverse probability of treatment weighting adjustment (adjusted odds ratio: 0.25; 95% CI, 0.0768–0.91; P=0.03). Multivariate logistic regression analysis showed that the treatment with vancomycin suspended in fibrin glue was significantly associated with a lower odds of SSI (odds ratio: 0.2; 95% CI, 0.05–0.85; P=0.03). Conclusions. The administration of vancomycin suspended in fibrin glue was significantly associated with a lower likelihood of SSI in patients undergoing spinal instrumentation surgery.