Counterpoint: the design and interpretation of blood transfusion randomized clinical trials.

A recent Perspective in Blood suggested that previous evidence from over a decade ago established that a liberal rather than a restrictive blood transfusion strategy results in better outcomes in patients with anemia and either acute myocardial infarction or stable cardiovascular disease. Their premise was that physiological evidence, and a different interpretation of the Transfusion Requirements in Critical Care (TRICC) trial should have been sufficient to establish clinical practice. They also suggest that a more personalized approach to the administration of transfusions would have been made possible by including a usual-care arm in all transfusion trials. In this counterpoint Perspective, we describe how and why 2 discrete and common blood transfusion thresholds were selected in the TRICC, FOCUS, REALITY, and MINT trials. We explain why a usual-care arm would have been uninformative. We also propose that we still do not have evidence to provide firm transfusion recommendations in several specific subpopulations of patients, including those with stable atherosclerotic coronary artery disease. Finally, we provide our perspective on the state of existing evidence and on the clinical recommendations that should be adopted in practice.