Preoperative Versus Extended Postoperative Antimicrobial Prophylaxis of Surgical Site Infection During Spinal Surgery: A Comprehensive Systematic Review and Meta-Analysis.

INTRODUCTION: Surgical site infection (SSI) following spinal surgery is a major source of postoperative morbidity. Although studies have demonstrated perioperative antimicrobial prophylaxis (AMP) to be beneficial in the prevention of SSI among spinal surgery patients, consensus is lacking over whether preoperative or extended postoperative AMP is most efficacious. To date, no meta-analysis has investigated the comparative efficacy of these two temporally variable AMP protocols in spinal surgery. We undertook a systemic review and meta-analysis to determine whether extended postoperative AMP is associated with a difference in the rate of SSI occurrence among adult patients undergoing spinal surgery. METHODS: Embase and MEDLINE databases were systematically searched for clinical trials and cohort studies directly comparing SSI rates among adult spinal surgery patients receiving either preoperative or extended postoperative AMP. Quality of evidence of the overall study population was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group approach. Random effects meta-analyses were performed utilizing both pooled and stratified data based on instrumentation use. RESULTS: Five studies met inclusion criteria. No individual study demonstrated a significant difference in the rate of SSI occurrence between preoperative and extended postoperative AMP protocols. The GRADE quality of evidence was low. Among the overall cohort of 2824 patients, 96% underwent lumbar spinal surgery. Pooled SSI rates were 1.38% (26/1887) for patients receiving extended postoperative AMP and 1.28% (12/937) for patients only receiving preoperative AMP. The risk of SSI development among patients receiving extended postoperative AMP was not significantly different from the risk of SSI development among patients only receiving preoperative AMP [RR (risk ratio), 1.11; 95% CI (confidence interval) 0.53-2.36; p = 0.78]. The difference in risk of SSI development when comparing extended postoperative AMP to preoperative AMP was also not significant for both instrumented (RR, 0.92; 95% CI 0.15-5.75; p = 0.93) and non-instrumented spinal surgery (RR, 1.25; 95% CI 0.49-3.17; p = 0.65). There was no evidence of heterogeneity of treatment effects for all meta-analyses. CONCLUSION: Preoperative AMP appears to provide equivalent protection against SSI development when compared to extended postoperative AMP. Prudent antibiotic use is also known to decrease hospital length of stay, healthcare expenditure, and risk of complications. However, until higher-quality evidence becomes available regarding AMP in spinal surgery, surgeons should continue to exercise discretion and clinical judgment when weighing the effects of patient comorbidities and complications before determining the optimal duration of perioperative AMP.