A meta-analysis of spinal surgical site infection and vancomycin powder

Object: Surgical site infection (SSI) is a serious and costly complication of spinal surgery. There have been several conflicting reports on the use of intrawound vancomycin powder in decreasing SSI in spine surgery. The purpose of this study is to answer the question: "Does intrawound vancomycin powder reduce the rate of SSIs in spine surgery?"

Methods: A comprehensive search of multiple electronic databases and bibliographies was conducted to identify clinical studies that evaluated the rates of SSI with and without the use of intrawound vancomycin powder in spine surgery. Independent reviewers extracted data and graded the quality of each paper that met inclusion criteria. A random effects meta-analysis was then performed.

Results: The search identified 9 retrospective cohort studies (Level III evidence) and 1 randomized controlled trial (Level II evidence). There were 2574 cases and 106 infections in the control group (4.1%) and 2518 cases and 33 infections (1.3%) in the treatment group, yielding a pooled absolute risk reduction and relative risk reduction of 2.8% and 68%, respectively. The meta-analysis revealed the use of vancomycin powder to be protective in preventing SSI (relative risk = 0.34, 95% confidence interval 0.17-0.66, p = 0.021). The number needed to treat to prevent 1 SSI was 36. A subgroup analysis found that patients who had implants had a reduced risk of SSI with vancomycin powder (p = 0.023), compared with those who had noninstrumented spinal operations (p = 0.226).

Conclusions: This meta-analysis suggests that the use of vancomycin powder may be protective against SSI in open spinal surgery; however, the exact population in which it should be used is not clear. This benefit may be most appreciated in higher-risk populations or in facilities with a high baseline rate of infection.