Secondary analysis of data from a prospective multicenter observational study.

To evaluate the occurrence of surgical site infection (SSI) in patients with and without intrawound vancomycin application controlling for confounding factors associated with higher SSI after elective spine surgery.

SSI is a morbid and expensive complication associated with spine surgery. The application of intrawound vancomycin is rapidly emerging as a solution to reduce SSI following spine surgery. The impact of intrawound vancomycin has not been systematically studied in a well-designed multicenter study.

Patients undergoing elective spine surgery over a period of four-years at seven spine surgery centers across the United States were included in the study. Patients were dichotomized based on whether intrawound vancomycin was applied. Outcomes were occurrence of SSI within postoperative 30-days and SSI that required return to the operating room (OR). Multivariable random effect log-binomial regression analyses were conducted to determine the relative risk of having a SSI and a SSI with return to OR.

A total of 2056 were included in the analysis. Intrawound vancomycin was utilized in 47% (n = 966) of patients. The prevalence of SSI was higher in patients with no vancomycin use (5.1%) compared to those with use of intrawound vancomycin (2.2%). The risk of SSI was higher in patients in whom intrawound vancomycin was not used (RR-2.5,p <  0.001), increased number of levels exposed (RR-1.1,p = 0.01), and those admitted postoperatively to intensive care unit (ICU) (RR-2.1,p = 0.005). Patients in whom intrawound vancomycin was not used (RR-5.9, p <  0.001), increased number of levels were exposed (RR-1.1,p = 0.001) and postoperative ICU admission (RR-3.3,p <  0.001) were significant risk factors for SSI requiring a return to the OR CONCLUSION.: The intrawound application of vancomycin after posterior approach spine surgery was associated with reduced risk of SSI and return to OR associated with SSI.