Risk Factors for Surgical Site Infections Following Spinal Fusion Surgery at a Children's Hospital

Abstract

BACKGROUND/OBJECTIVES: Postoperative infections especially surgical site infections (SSIs) are serious complications of spine fusions requiring extensive medical care and frequently additional surgical intervention. Between 1996 and 1999 at a children's hospital, a significant increase in the SSI rate was identified in patients with no known risk factors for infection preoperatively. The objectives of the study were to identify specific risk factors for SSIs in patients undergoing spinal fusion surgery and to analysis the characteristics of these infections. METHODS: A retrospective cohort study with medical chart review of all patients (ages 6 months to 21 years of age) who underwent spine fusion surgery between Jan. 1999 and Dec. 2003. Risk factors for SSI were determined using univariate analysis and multivariate logistic regression. SSIs were analyzed using CDC and NNSI guidelines. RESULTS: During the 5-year study, 234 spine fusion surgeries were performed with 19 (8%) patients developing a SSI. Univariate analysis identified diagnosis (idiopathic, neuromuscular, or structural scolotic curves), a secondary condition (such as cerebral palsy, myelodysplasia, an autoimmune condition, or genetic syndromes), and ASA score were significant preoperative risks with cut time, blood loss, blood replacement (type and amount), and bone graft used significant procedural risks. Postoperatively, hospital length of stay, antibiotic use, transfer to the ICU, and other non-infectious postoperative problems were significant. In the multivariate logistic regression, only cut time remained significant. Of the 19 SSIs, 11 (58%) occurred ≤ 30 days; 3 (16% occurred between 31 to 365 days, and 5 (26%) were identified more than 366 days postoperatively. Sixty three percent were classified as organ/space infections, requiring extensive medical intervention. Comparison of National Nosocomial Infection Surveillance risk index and study population infection rates Number of Risk Factor NNIS Rate Study Population Rate 0 1.2% 1.3% 1 3.1% 5.1% 2,3 7.2% 1.7% CONCLUSIONS: Diagnosis, cut time and ASA were found to be significant in this study. The identification of SSIs after 366 days (2 to 5 years) postoperatively is becoming an increasing concern requiring surveillance for infection to continue for several years to determine the actual SSI rate for this population of patients.