Homologous blood transfusion as a risk factor for postoperative infection after coronary artery bypass graft operations.

Homologous transfusions are immunosuppressive and associated with a higher risk of postoperative infection. In this retrospective analysis, we studied 238 consecutive patients who underwent first-time coronary operations by a single surgeon in 1988 to 1989 and collected clinical and laboratory data relevant to postoperative infections including pulmonary, urinary, and wound sites. Culture-proved postoperative infections occurred in 16 of the 238 patients (6.7%), with only 3 (1.3%) being deep sternal wound infections. Seven of 16 (44%) of the infections were away from the wound sites, suggesting that nonsurgical variables contributed to at least some infections. Factors significantly associated with an increased risk of postoperative infection by univariate analysis included female sex, diabetes mellitus, and transfusion dose. Infections occurred in 3.9% of patients receiving up to 2 units of red cells and whole blood, 6.9% receiving 3 to 5 units, and 22% of those receiving 6 units or more. Multiple linear and logistic regression analysis showed that transfusion dose was the most significant predictor of infection, days of fever, days of antibiotic therapy, and length of hospital stay. Homologous transfusion is associated (in a dose-dependent fashion) with a threefold to eightfold increased risk of postoperative infection in patients undergoing coronary artery operations. This increased risk of infection may be due to transfusion-induced immunosuppression of the patient.