The Incidence and Factors Associated with Graft Infection After Aortic Aneurysm Repair

Objectives: The reported rate of abdominal aortic graft infections (AGIs) is low, but its incidence and associated factors have not been evaluated on a population level. We hypothesized that AGI occurs more often in patients with periprocedural nosocomial infections and less often after endovascular aneurysm repair (EVAR).

Methods: A retrospective cohort study was done of all patients undergoing abdominal aortic aneurysm (AAA) repair (1987-2005) in Washington State by using the Comprehensive Hospital Abstract Reporting System (CHARS) data. Nosocomial infection was defined as one or more of pneumonia, urinary tract infections, blood stream septicemia, or surgical site infection at the index admission. Readmissions and reintervention for graft infections defined AGIs excluding the diagnostic code of renal failure or those who appeared to have dialysis grafts.

Results: Between 1987 and 2005, 13,902 patients (mean age, 71.3 +/- 8.8 years; 90.8% men) underwent AAA repair (12,626 open, 1276 EVAR). The cumulative rate of AGIs in the cohort was 0.44%. The 2-year rate of AGI was 0.19% among open vs 0.16% in EVAR (P = .75) and 0.2% in both elective and nonelective patients. Open procedures had greater rates of perioperative pneumonia (11.1% vs 2.4%, P < .001), blood stream septicemia (1.6% vs 0.7%, P < .01), and surgical site infection (.5% vs 0%, P < .012) compared with EVAR. When individually analyzed, blood stream septicemia (.93% vs 18%, P = .014) and surgical site infection (1.61% vs 0.19%, P = .01) were significantly associated with AGIs. The median time to AGI was 3.0 years, and AGI presented sooner (< or =1.4 years) if nosocomial infection occurred at the index admission. This risk of developing AGI after open repair was highest in the first postoperative year (32% of all AGI occurred in year 1). In an adjusted model, blood stream septicemia was significantly associated with AGI (odds ratio, 4.2; 95% confidence interval, 1.5-11.8)

Conclusions: The incidence of AGI was low, presented most commonly in the first postoperative year, and was similar among patients undergoing open AAA repair and EAVR. Patients with nosocomial infection had an earlier onset of AGI. The 2-year rate of AGI was significantly higher in patients who had blood stream septicemia and surgical site infection in the periprocedural hospitalization. These data may be helpful in directing surveillance programs for AIG.