Surgical-site infection rates and risk factor analysis in coronary artery bypass graft surgery

The Victorian Infection Control Surveillance Project (VICSP) is a multicenter collaborative surveillance project established by infection control practitioners. Five public hospitals contributed data for patients undergoing coronary artery bypass graft (CABG) surgery.

To determine the aggregate and comparative interhospital surgical-site infection (SSI) rates for patients undergoing CABG surgery and the risk factors for SSI in this patient group.

Each institution used standardized definitions of SSI, risk adjustment, and reporting methodology according to the National Nosocomial Infections Surveillance System of the Centers for Disease Control and Prevention. Data on potential risk factors were prospectively collected.

For 4,474 patients undergoing CABG surgery, the aggregate SSI rate was 7.8 infections per 100 procedures (95% confidence interval [CI95], 7.0-8.5), with individual institutions ranging between 4.5 and 10.7 infections per 100 procedures. Multivariate risk factor analysis demonstrated age (odds ratio [OR], 1.02; CI95, 1.01-1.04; P < .001), obesity (OR, 1.8; CI95, 1.4-2.3; P < .001), and diabetes mellitus (OR, 1.6; CI95, 1.2-2.1; P < .001) as independent predictors of SSI. Three hundred thirty-four organisms were isolated from 296 SSIs. Of the total SSIs, methicillin-resistant Staphylococcus aureus was isolated from 32%, methicillin-sensitive S. aureus from 24%, gram-negative bacilli (eg, Enterobacter and Escherichia coli) from 18%, and miscellaneous organisms from the remainder.

We documented aggregate and comparative SSI rates among five Victorian public hospitals performing CABG surgery and defined specific independent risk factors for SSI. VICSP data offer opportunities for targeted interventions to reduce SSI following cardiac surgery.