Aspirin plus clopidogrel and risk of infection after coronary artery bypass surgery

Background: The risks associated with the use of the combination of aspirin and clopidogrel before surgery are incompletely understood. Pharmacologic suppression of platelet function may increase the risk of postoperative infection by inhibiting hemostasis, immunity, or both. Methods: We performed a retrospective cohort study of 1677 patients undergoing coronary artery bypass surgery to determine the relationship of the preoperative use of aspirin plus clopidogrel vs aspirin alone to the 30-day incidence of postoperative surgical site infection and bacteremia. Results: The cumulative incidence of infection at 30 days was 23.1% and 16.1% in patients who were receiving dual antiplatelet therapy and aspirin monotherapy, respectively (unadjusted hazard ratio [HR], 1.51; 95% confidence interval [CI], 1.09-2.08). The risk of infection remained higher among patients who were receiving dual antiplatelet therapy after adjustment for demographic, socioeconomic, preoperative, and intraoperative risk factors (HR, 1.42; 95% CI, 1.01-2.00) and propensity score (HR, 1.43; 95% CI, 1.01-2.01]). Transfusion rates were also higher among patients who were receiving dual antiplatelet therapy than among patients who were receiving aspirin monotherapy (68.4% vs 60.4%, P=.04), but transfusion played a modest role in mediating the risk of infection (adjusted HR, 1.37; 95% CI, 0.96-1.93]). Mortality rates at 30 days were 5.2% and 3.1% in patients who were receiving dual antiplatelet and aspirin monotherapy, respectively (adjusted HR, 1.44; 95% CI, 0.70-2.99]). Conclusions: Preoperative use of aspirin plus clopidogrel is associated with an increased risk of infection after coronary artery bypass surgery. These findings merit additional work to clarify the risks and benefits of uninterrupted dual antiplatelet therapy in surgical patients and the impact of platelet inhibition on infectious outcomes in populations that are at heightened infectious risk.