Past history of skin infection and risk of surgical site infection after elective surgery

OBJECTIVE: To identify baseline patient characteristics associated with increased susceptibility to surgical site infection (SSI) after elective surgery. BACKGROUND: The Center for Medicare and Medicaid Services considers SSI to be preventable through adherence to current infection control practices; however, the etiology of wound infection is incompletely understood. METHODS: Prospective cohort study involving patients undergoing cardiac, vascular, craniotomy, and spinal surgery at 2 academic medical centers in Baltimore, MD. A comprehensive medical history was obtained at baseline, and participants were followed for 6 months using active inpatient and outpatient surveillance for deep SSI and infectious death. Infection control best practices were monitored perioperatively. The relative risk of SSI/infectious death was determined comparing those with versus those without a past medical history of skin infection using Cox proportional hazards models. RESULTS: Of 613 patients (mean [SD] = 62.3 [11.5] years; 42.1% women), 22.0% reported a history of skin infection. The cumulative incidence of deep SSI/infectious death was 6.7% versus 3.1% for those with and without a history of skin infection, respectively (unadjusted hazard ratio (HR) = 2.25; 95% confidence interval (95% CI), 0.98-5.14; P = 0.055). Risk estimates increased after adjustments for demographic and socioeconomic variables (HR = 2.82; 95% CI, 1.18-6.74; P = 0.019) and after propensity score adjustment for all potential confounders (HR = 3.41; 95% CI, 1.36-8.59; P = 0.009). Adjustments for intraoperative infection risk factors and adherence to infection control best practice metrics had no impact on risk estimates. CONCLUSIONS: A history of skin infection identified a state of enhanced susceptibility to SSI at baseline that is independent of traditional SSI risk factors and adherence to current infection control practices.