Dear Editor,

We agree with Dr. Perner and colleagues’ clarification [1] that the results of the TRISS trial are easily interpreted. Another recent trial on blood transfusions after cardiac surgery [2] reached a similar conclusion. We are concerned that in these prospective randomized controlled trials, some patients are not transfused when they would likely have benefited from this intervention, and others are transfused when they should not have been, so the results show similar outcomes in the two groups. It would seem preferable to individualize the decision to transfuse by integrating individual physiological and clinical factors with the hemoglobin concentration [3]. If achievable, such an approach would provide benefit to the transfused patient, and avoid unneeded exposure to blood transfusions in many others.