What are the risk factors for surgical site infection after spinal fusion? A meta-analysis.

PURPOSE: Although many risk factors for surgical site infection (SSI) following spinal fusion have been described in the literature, methodologies and study cohorts vary widely. Patient- and procedure-specific risk factors for (SSI) can be identified via a meta-analysis. We sought to review the existing data and isolate significant risk factors for SSI in patients undergoing thoracolumbar spinal fusion.

METHODS: The literature was searched through December of 2016. Studies including adult patients undergoing thoracolumbar spinal fusion surgery (single or multilevel, anterior, posterior or combined approach) were identified. Only studies that included an odds ratio (OR) for SSI or sufficient data to calculate it were included. A meta-analysis was performed using RevMan 5.1. Depending on heterogeneity (I2 ), OR with 95% confidence intervals was calculated using either the fixed-effects model (when I2  < 60%) or the random-effects model (when I2  > 60%).

RESULTS: 6482 manuscripts were identified and reviewed. 29 manuscripts with 374,488 patients met the criteria for inclusion. Twelve risk factors were assessed by the meta-analysis and grouped into two categories (patient related and procedure related). Significant patient-related factors for SSI included obesity, diabetes, ASA score, tobacco use and revision status. Procedure-related risk factors included operative time, use of osteotomy, fusion length and extension of fusion to the sacrum or pelvis.

CONCLUSIONS: This meta-analysis identified significant risk factors for SSI following spine arthrodesis. These included potentially modifiable factors such as obesity, diabetes, smoking status and procedure-related parameters. Non-modifiable risk factors were identified, including ASA score and age. These factors may prove useful for patient counseling as well as surgical planning.

LEVEL OF EVIDENCE: Level III (Meta-analysis including studies with a level of evidence of III or higher). These slides can be retrieved under Electronic Supplementary Material.