Background
Healthcare acquired infections (HAIs) are a leading cause of morbidity and mortality after cardiac surgery. Prior work has identified a number of patient-related risk factors associated with HAIs. We hypothesized that rates of HAIs would differ across institutions, in part attributed to differences in case mix.
Methods and Results
We analyzed 20,896 patients undergoing isolated coronary artery bypass grafting (CABG) surgery at 33 medical centers in Michigan between 1/1/2009–6/30/2012. Overall HAIs included pneumonia, sepsis/septicemia, and surgical site infections, including deep sternal wound, thoracotomy, and harvest/cannulation site infections. We excluded patients presenting with endocarditis. Predicted rates of HAIs were estimated using multivariable logistic regression. Overall rate of HAI was 5.1% (1,071 of 20,896) [isolated pneumonia: 3.1% (n=644), isolated sepsis/septicemia: 0.5% (n=99), isolated deep sternal wound infection: 0.5% (n=96), isolated harvest/cannulation site: 0.5% (n=97), isolated thoracotomy: 0.02% (n=5), multiple infections: 0.6% (n=130)]. HAI subtypes differed across strata of center-level HAI rates. While predicted risk of HAI differed in absolute terms by 2.8% across centers (3.9%–6.7%, min:max), observed rates varied 18.2% (0.9%–19.1%).
Conclusions
There was an 18.2% difference in observed HAI rates across medical centers among patients undergoing isolated CABG surgery. This variability could not be explained by patient case mix. Future work should focus on the impact of other factors (e.g. organizational and systems of clinical care) on risk of HAIs.