Prolonged effect of postoperative infectious complications on survival after cardiac surgery

Background Whether patients having infections after cardiac surgery are at a survival disadvantage after hospital discharge is unclear. Our objectives were (1) to identify characteristics of such patients and (2) to determine whether this complication is associated with increased mortality beyond hospital discharge. Methods In all, 30,414 patients were discharged after isolated coronary artery bypass grafting, valve, ascending aorta repair, or combined procedures from January 2000 to January 2011. Surgical site infection, septicemia, pneumonia, and urinary tract infection occurred in 1,868 patients (6.1%). Propensity matching was used to account for differences in perioperative characteristics and postoperative in-hospital events between these patients and those not having postoperative infections, to give 1,593 propensity-matched pairs. Time-related mortality and instantaneous risk were compared. Results Surgical site infection occurred in 122 patients (0.40%), sternal wound infection in 263 (0.86%), septicemia in 656 (2.2%), urinary tract infection in 853 (2.8%), and pneumonia in 513 (1.7%). Infections were associated with older age, female sex, larger body mass index, and multiple comorbidities. Among 1,593 propensity-matched pairs, postdischarge survival at 6 months and at 1, 5, and 10 years, respectively, was 89%, 86%, 67%, and 45% for patients without infections, and 86%, 83%, 63%, and 43% (p = 0.008) for patients with infections. Survival differences resulted from a higher, but gradually declining, early instantaneous risk during the first year after surgery. Elevated risk was of shorter duration for surgical site infections than for other infections. Conclusions Postoperative infection is associated with a high-risk patient profile, and risk of death is elevated early after hospital discharge. Reasons for this prolonged effect are unclear.