Risk factors for surgical site infection after posterior cervical spine surgery: an analysis of 5,441 patients from the ACS NSQIP 2005–2012

Abstract

Background ContextThe incidence of surgical site infection (SSI) following posterior cervical surgery has been reported as high as 18% in the literature. Few large studies have specifically examined posterior cervical procedures. PurposeThe study aims to examine the incidence, timing, and risk factors for SSI following posterior cervical surgery. DesignThis is a retrospective cohort study of prospectively collected data in a national surgical outcomes database. Patient SampleThe sample includes patients who underwent posterior cervical spine surgery between 2005 and 2012 identified in the American College of Surgeons National Surgical Quality Improvement Project (ACS NSQIP) Participant Use Data File. Outcome MeasuresThe 30-day rate of postoperative SSI, timing of diagnosis, and associated risk factors were determined. MethodsThe ACS NSQIP was used to identify 5,441 patients who underwent posterior cervical spine surgery by Current Procedural Terminology codes from 2005 to 2012. Thirty-day readmission data were obtained for 2011–2012. The incidence and timing of SSI were determined. Multivariable logistic regression analysis was then performed to identify significant risk factors. ResultsOf the 5,441 patients identified as having undergone posterior cervical surgery, 3,724 had a posterior cervical decompression, 1,310 had a posterior cervical fusion, and 407 underwent cervical laminoplasty. Surgical site infection within 30 days was identified in 160 patients (2.94%), with 80 of those cases being superficial SSI. There was no significant difference in SSI rate among the three procedure groups. The average time for diagnosis of SSI was over 2 weeks. In 2011–2012, 36.9% of patients with SSI were readmitted within 30 days. Several significant predictors of SSI were identified in univariate analysis, including body mass index (BMI) >35, chronic steroid use, albumin <3, hematocrit <33, platelets <100, higher American Society of Anesthesiologists class, longer operative time, and longer hospital admission. Independent risk factors, including BMI >35 (odds ratio [OR]=1.78, p=.003), chronic steroid use (OR=1.73, p=.049), and operative time >197 minutes (OR=2.08, p=.005), were identified in multivariable analysis. ConclusionsOptimization of preoperative nutritional status, serum blood cell counts, and operative efficiency may lead to a reduction in SSI rates. Obese patients and patients on chronic steroid therapy should be counseled on elevated SSI risk.