Cost of surgical site infections following coronary artery bypass surgery

Little information is available on the financial impact of surgical site infections (SSI) after major surgery. In order to calculate the cost of SSI following coronary artery bypass graft surgery (CABGs), a 2-year retrospective case-control study was undertaken at Alfred Hospital, a university-affiliated tertiary referral centre.

One hundred and eight patients with SSI (cases) after CABGs and 108 patients without SSI (controls) were matched for gender, age, risk index (Centers of Disease Control and Prevention, National Nosocomial Infection Surveillance (NNIS) System) and number of principal comorbidities. The patient's postoperative length of stay (LOS), in both the intensive care unit (ICU) and the non-ICU (general) ward, was obtained from the medical records and the cost of a day in each was provided by the hospital's finance department. The cost of antibiotics prescribed for SSI was provided by the hospital's pharmacy department.

Postoperatively the cases were in ICU for a total of 313 days whereas the controls spent 165 days in ICU, a mean of 2.89 versus 1.53 days, respectively (P = 0.035). In general wards, cases were inpatients for a total of 1651 days and controls for 589 days. This is a mean of 10.8 days for cases and 4.7 days for controls (P = 0.0001). The extra LOS for 108 cases (compared to the controls) was costed at $1 299 082, a mean cost of $12 028 per patient. The total cost of antibiotics prescribed for these SSI was $42 270 (a cost per case of $391). The total excess cost related to increased LOS and antibiotic treatment was $12 419 per patient. In the subgroup analysis for deep sternal site infections the mean excess cost was $31 597 per patient.

Postoperative SSI result in significant patient morbidity and consume considerable resources. In the present study, patients with SSI following CABGs had significant prolongation of hospitalization (both in ICU and general wards). The present study illustrates the potential cost savings of introducing interventions to reduce SSI rates. This is the first time such a study has been undertaken in Australia.