Dr. Likosky and colleagues report a retrospective analysis of more than 16,000 patients undergoing coronary artery bypass graft surgery, in whom the impact of blood transfusion on the rate of postoperative pneumonia was described.

The adjusted multivariable analysis revealed that transfusion was not only an independent risk factor for pneumonia, but also that the number of transfusions were more or less almost linearily associated with the risk of pneumonia. These findings are in agreement with earlier results from the literature, although the pathophysiological mechanism has yet to be elucidated.

Major weaknesses of this work are 1) the retrospective design of this database analysis, which does not allow the identification of a causal relationship between transfusion and pneumonia, 2) the repetition of previously published results, and 3) the lack of an overall leucoreduction in the packed red blood cells being transfused.

– Christian von Heymann