Background: Several studies suggest that perioperative blood transfusion is a major independent risk factor for postoperative bacterial infections. Transfusion-induced immunosuppression is thought to mediate this effect.
Study design and methods: In a randomized clinical trial comprising 697 patients with colorectal cancer, the relationship between two types of red cell components (buffy coat-depleted packed red cells and white cell-reduced [filtered] packed red cells) and postoperative bacterial infections was analyzed.
Results: Both types of red cells appeared to be associated with a greater incidence of postoperative infection than was no transfusion (39 vs. 24%, p < 0.01). A dose-response relationship could be demonstrated: the corrected relative risk was 1.6 for 1 to 3 units of red cells and 3.6 for more than 3 units. Multivariate analyses identified the transfusion of red cells and tumor location as the only significant independent risk factors for postoperative bacterial infection.
Conclusion: Because allogeneic white cells, plasma, microaggregates, citrate, and platelets could be ruled out as risk factors for transfusion-associated postoperative infections, it is hypothesized that the transfusion of red cells is a potentially detrimental factor that transiently impairs the clearance of bacteria by phagocytic cells.