The Effect of Postoperative Spinal Infections on Patient Mortality

STUDY DESIGN: A retrospective, matched cohort study. OBJECTIVES: This study aims to investigate the association between surgical site infection (SSI) and mortality and ascertain any factors that predict mortality in those diagnosed with SSI. SUMMARY OF BACKGROUND DATA: Despite significant efforts toward mitigation, SSI, including deep infection, remains a common complication following spine surgery, Considerable morbidity may be associated with infection, including hospital readmission, revision surgery, and delayed rehabilitation. However, it is not known whether this increase in morbidity is associated with increased mortality. METHODS: Patients from a single center requiring reoperation for SSI following elective spine surgery between 2005 and 2013 were identified in a retrospective fashion. These patients were then matched one-to-three with patients undergoing elective spine surgery without SSI. Patients were matched for age, gender, body mass index (BMI), Charlson comorbidity index, year of surgery, spine region, and approach. The Social Security Death Index was utilized to identify deceased patients and their time of death. Univariate statistics were then utilized to compare mortality rates between the two groups. In addition, the SSI cohort was evaluated for predictors of mortality following SSI. RESULTS: One-hundred ninety-five patients developed SSI at a mean of 27.4 (range: 1-467) days from the index surgery. Ninety-day, 1-year, 2-year, and 5-year mortality rates were 1.54% versus 1.03% (P = 0.70), 4.62% versus 1.2% (P = 0.006), 7.73% versus 2.25% (P = 0.001), and 15.45% versus 3.43% (P = 0.0002) for SSI versus control patients, respectively. Predictors of 2-year mortality in the SSI cohort were increased age (P = 0.02) and increased Charlson Comorbidity Index (P < 0.001). Region and approach of surgery, days to infection, and reason for elective surgery did not influence mortality. CONCLUSION: SSI results in significant morbidity in the postoperative period, with the risk of reoperation, prolonged hospitalization, and need for other invasive procedures. In addition, this study provides evidence that SSI is associated with an increased mortality following elective spine surgery. LEVEL OF EVIDENCE: 4.