Abstract 120: Regional Variation in Infection Rates after Coronary Artery Bypass Grafting

Abstract

Introduction: 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. Hypothesis: We hypothesized that rates of HAIs would differ across institutions, in part attributed to differences in case mix. Methods: We enrolled 27,663 patients undergoing isolated coronary artery bypass grafting (CABG) surgery at 33 medical centers in Michigan between 1/1/2008 - 6/30/2012. Overall HAIs included pneumonia, sepsis/septicemia, 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. Results: Overall rate of HAI was 5.3% (1454 of 27,663) [pneumonia: 3.7% (n=1020), sepsis/septicemia: 1.0% (n=266), deep sternal wound: 0.7% (n=184), harvest/cannulation site: 0.6% (n=163), multiple infections: 0.6% (n=169)]. While predicted risk of HAI differed in absolute terms by 4.1% across centers (4.2% - 8.3%, min:max), observed rates varied from 1.3% to 20.8%, p<0.01 (Figure). Conclusions: There was a 16-fold variability in rates of HAIs 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.