Risk Factors for Surgical Site Infection Following Spinal Surgery

Methods: ICD-9 codes from administrative databases identified all patients having spinal laminectomy or fusion at our institution between April 1, 2001 and December 31, 2004. Medical records of patients were reviewed by hospital infection control to identify cases of SSI using Centers for Disease Control and Prevention (CDC) criteria. A case-control investigation compared SSI patients to controls randomly selected from a list of patients without SSI who underwent spinal surgery. One control per case was used and group matching by year was employed.

Results: 104 cases of SSI were identified among 3,894 laminectomy or fusion procedures for an overall infection rate of 2.67%. Multivariate analysis identified independent risk factors for SSI including prolonged duration of procedure (odds ratio [OR] 3.0, 95% Confidence interval [CI] 1.1-7.9, P=0.03), American Society of Anesthesiologists (ASA) score 3 or greater (OR 9.1, 95% CI 3-28, P<0 .001).

Conclusions: Prolonged surgical duration, high ASA score, obesity and surgery at the lumbosacral junction were independent risk factors for SSI following spinal surgery. Avoiding hair removal and administering at least 50% FiO2 were highly protective against SSI. A prospective evaluation of these interventions is needed to assess their efficacy for preventing SSI following spinal surgery.