Long-term health outcomes and health system costs associated with surgical site infections: a retrospective cohort study

Objectives — To examine the association between surgical site infections (SSIs) and hospital readmissions and all-cause mortality, and to estimate the attributable healthcare costs of SSIs 1 year following surgery.

Background — SSIs are a common postoperative complication; the long-term impact of SSI on health outcomes and costs has not been formally evaluated.

Methods — This retrospective cohort study included all adult patients who underwent surgery at the 1202-bed teaching hospital in Ottawa, Ontario, Canada, and were included in the National Surgical Quality Improvement Program database between 2010 and 2015. The study exposure was postoperative SSI. The study outcomes included hospital readmission, all-cause mortality, and healthcare costs at 1 year (primary) and at 30 days and 90 days (secondary) following surgery.

Results — We identified 14,351 patients, including 795 patients with SSIs. Our multivariable analyses that accounted for competing risks demonstrated that at 1-year following the index date, superficial and deep/organ space SSIs were significantly associated with an increase in hospital readmission [hazard ratio (HR) = 1.63, 95% confidence interval (95% CI) 1.39-1.92 and HR = 3.49, 95% CI 2.76-4.17, respectively) and all-cause mortality (HR = 1.35, 95% CI 1.10-1.98 and HR = 2.21, 95% CI 1.44-2.78, respectively]. At 1 year after surgery, patients with superficial and deep/organ space SSIs incurred higher healthcare costs C$20,648 (95% CI C$16,980- C$24,112and C$53,075 (95% CI C$44,628- C$60,936), than non-SSI patients.

Conclusion — SSIs, especially deep/organ space SSI, contribute to adverse health outcomes and healthcare costs across the entire year after surgery. Our findings highlight the importance of effective prevention/monitoring strategies targeting both short- and long-term consequences of SSI.