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:Most posterior spinal fusion (PSF) patients do not require admission to an intensive care unit (ICU), and those who do may represent an underinvestigated, high-risk subpopulation.OBJECTIVE:To identify the microbial profile of and risk factors for surgical site infection (SSI) in PSF patients admitted to the ICU postoperatively.METHODS:We examined 3965 consecutive PSF patients treated at our institution between 2000 and 2015 and collected demographic, clinical, and procedural data. 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 cerebrospinal fluid 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 = .0171, R = 0.941), with a 3-fold higher odds of SSI in the highest risk group than the lowest (odds ratio = 3.15 [1.19, 8.07], P = .032).CONCLUSION: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 3-fold greater odds of SSI for high-risk patients than low-risk patients.

Surgery Decreases Nonunion, Myelopathy, and Mortality for Patients With Traumatic Odontoid Fractures: A Propensity Score Matched Analysis

“…However, these series do not adjust for other commonly accepted risk factors for negative outcomes: The ISS is a well validated predictor of trauma-related mortality, and spine patients selected for ICU admission are a high-risk population known to have an elevated incidence of adverse events. 19 - 21 Fagin et al 37 did collect data on ISS but did not adjust or control for this or other confounders with respect to mortality rate. Fehlings et al 38 adjusted for demographic, comorbid disease burden, and ISS but did not examine mortality rate alone, instead assessing a compositive of death, worsened neck disability index, and treatment-related complications using Cox proportional hazards analysis.…”

“… 19 Moreover, spine patients selected for intensive care unit (ICU) admission are known to represent a high-risk patient subgroup; therefore, a providers' clinical judgment to select a patient for ICU admission is likely to be clinically relevant. 20 , 21 In addition, neurological impairment may spur the decision to pursue surgery and which may affect a patient's long-term function and prognosis. Without controlling for these factors, any calculated survival benefit associated with surgery is highly confounded.…”

Commentary: 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

“…[3][4][5][6][7] The authors conducted a retrospective study at a single institution over a 15-year period and identified 3965 patients who underwent PSF. 8 They examined the differences in microbial profile of SSIs in PSF patients admitted to the ICU vs non-ICU after surgery. They found that 16.2% of patients were admitted to the ICU postoperatively.…”