Risk factors associated with surgical site infection after pediatric posterior spinal fusion procedure

Abstract

Objective: To identify risk factors associated with surgical site infection (SSI) after pediatric posterior spinal fusion procedure by examining characteristics related to the patient, the surgical procedure, and tissue hypoxia.

Design: Retrospective case-control study nested in a hospital cohort study.

Setting: A 475-bed, tertiary care children's hospital.

Methods: All patients who underwent a spinal fusion procedure during the period from January 1995 through December 2006 were included. SSI cases were identified by means of prospective surveillance using National Nosocomial Infection Surveillance system definitions. Forty-four case patients who underwent a posterior spinal fusion procedure and developed an SSI were identified and evaluated. Each case patient was matched (on the basis of date of surgery, +/-3 months) to 3 control patients who underwent a posterior spinal fusion procedure but did not develop an SSI. Risk factors for SSI were evaluated by univariate analysis and multivariable conditional logistic regression. Odds ratios (ORs), with 95% confidence intervals (CIs) and P values, were calculated.

Results: From 1995 to 2006, the mean annual rate of SSI after posterior spinal fusion procedure was 4.4% (range, 1.1%-6.7%). Significant risk factors associated with SSI in the univariate analysis included the following: a body mass index (BMI) greater than the 95th percentile (OR, 3.5 [95% CI, 1.5-8.3]); antibiotic prophylaxis with clindamycin, compared with other antibiotics (OR, 3.5 [95% CI, 1.2-10.0]); inappropriately low dose of antibiotic (OR, 2.6 [95% CI, 1.0-6.6]); and a longer duration of hypothermia (ie, a core body temperature of less than 35.5 degrees C) during surgery (OR, 0.4 [95% CI, 0.2-0.9]). An American Society of Anesthesiologists (ASA) score of greater than 2, obesity (ie, a BMI greater than the 95th percentile), antibiotic prophylaxis with clindamycin, and hypothermia were statistically significant in the multivariable model.

Conclusion: An ASA score greater than 2, obesity, and antibiotic prophylaxis with clindamycin were independent risk factors for SSI. Hypothermia during surgery appears to provide protection against SSI in this patient population.