123. Surgical site infection in the intensive care setting after posterior spinal fusion: a case series highlighting the microbial profile, risk factors and the importance of comorbid disease burden

Abstract

BACKGROUND CONTEXT Most posterior spinal fusion (PSF) patients do not require admission to an intensive care unit (ICU), and those who do may represent an under-investigated, high-risk subpopulation. PURPOSE To identify the microbial profile of and risk factors for surgical site infection (SSI) in PSF patients admitted to the ICU postoperatively. STUDY DESIGN/SETTING Retrospective chart review of patients at an urban, academic, tertiary referral center. PATIENT SAMPLE We examined 3,965 consecutive PSF patients treated at our institution between 2000 and 2015. OUTCOME MEASURES Surgical site infection, 30-day readmission, and reoperation. METHODS We collected demographic, clinical and procedural data on all patients included. Comorbid disease burden was quantified using the Charlson Comorbidity Index (CCI). We performed multivariable logistic regression to identify risk factors for SSI, readmission, and reoperation. RESULTS Anemia, more levels fused, cervical surgery, and CSF leak were positively associated with ICU admission, and minimally invasive surgery was negatively associated. The median time to infection was equivalent for ICU patients and non-ICU patients, and microbial culture results were similar between groups. Higher CCI and undergoing a staged procedure were associated with readmission, reoperation and SSI. When stratified by CCI into quintiles, SSI rates show a strong linear correlation with CCI (p=0.0171, R2=0.885), with a threefold higher odds of SSI in the highest risk group than the lowest (OR=3.15 [1.19, 8.07], p=0.032). CONCLUSIONS Procedural characteristics drive the decision to admit to the ICU postoperatively. Patients admitted to the ICU have higher rates of SSI, but no difference in the timing of or microorganisms that lead to those infections. Comorbid disease burden drives SSI in this population, with a threefold greater odds of SSI for high risk patients than low risk patients. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Most posterior spinal fusion (PSF) patients do not require admission to an intensive care unit (ICU), and those who do may represent an under-investigated, high-risk subpopulation. To identify the microbial profile of and risk factors for surgical site infection (SSI) in PSF patients admitted to the ICU postoperatively. Retrospective chart review of patients at an urban, academic, tertiary referral center. We examined 3,965 consecutive PSF patients treated at our institution between 2000 and 2015. Surgical site infection, 30-day readmission, and reoperation. We collected demographic, clinical and procedural data on all patients included. Comorbid disease burden was quantified using the Charlson Comorbidity Index (CCI). We performed multivariable logistic regression to identify risk factors for SSI, readmission, and reoperation. Anemia, more levels fused, cervical surgery, and CSF leak were positively associated with ICU admission, and minimally invasive surgery was negatively associated. The median time to infection was equivalent for ICU patients and non-ICU patients, and microbial culture results were similar between groups. Higher CCI and undergoing a staged procedure were associated with readmission, reoperation and SSI. When stratified by CCI into quintiles, SSI rates show a strong linear correlation with CCI (p=0.0171, R2=0.885), with a threefold higher odds of SSI in the highest risk group than the lowest (OR=3.15 [1.19, 8.07], p=0.032). Procedural characteristics drive the decision to admit to the ICU postoperatively. Patients admitted to the ICU have higher rates of SSI, but no difference in the timing of or microorganisms that lead to those infections. Comorbid disease burden drives SSI in this population, with a threefold greater odds of SSI for high risk patients than low risk patients.