Impact of postdischarge surveillance on surgical-site infection rates for coronary artery bypass procedures

OBJECTIVE: To assess the influence of postdischarge infection surveillance on risk-adjusted surgical-site infection rates for coronary artery bypass graft (CABG) procedures. DESIGN: Prospective surveillance of surgical-site infections after CABG. SETTING: Tertiary-care referral hospital. METHODS: Data on surgical-site infections were collected for 1,324 CABG procedures during 27 months. They were risk adjusted and analyzed according to the surgical surveillance protocol of the National Nosocomial Infections Surveillance (NNIS) System of the Centers for Disease Control and Prevention, with and without postdischarge data. RESULTS: Data were available for 96% of the patients. Of the 88 surgical-site infections, 28% were identified prior to discharge and 72% postdischarge. More chest than harvest-site infections were identified (46% vs 11%) prior to discharge, and more harvest-site than chest infections were identified in the outpatient setting (42% vs 14%). The surgical-site infection rate for patients stratified under risk index 1, calculated without postdischarge surveillance, was 2.9%; when compared with that of the NNIS System, the P value was .29. When postdischarge surveillance was included, the surgical-site infection rate was 4.9% and statistically significant when compared with that of the NNIS System (P = .007). For patients stratified under risk index 2, the rates with and without postdischarge surveillance were 11.7% and 10.0%, respectively; when compared with the NNIS System rates, the P values were .000008 and .0006, respectively. CONCLUSIONS: Only 28% of the surgical-site infections would have been detected if surveillance had been limited to hospital stay. Postdischarge surveillance identified more surgical-site infections among risk index 1 patients. Hospitals with comprehensive postdischarge surveillance after CABG procedures are likely to record higher surgical-site infection rates than those that do not perform such surveillance.