This narrative review critically evaluates the evidence for risk of
anemia and red blood cell (RBC) transfusion. For this purpose, it assesses large prospective randomized-controlled trials (RCTs) in medical, surgical, and
critical care patient populations in which the impact of specific
hemoglobin transfusion thresholds are compared. In these trials, the risks of
anemia relative to those of RBC transfusion are assessed. The results of published systematic reviews and meta-analyses are also discussed. Lastly, recommendations for patient blood management and treatment of
anemia are explored. The main conclusion of this review emphasizes that the decision to transfuse RBCs is complex and depends on the interaction between multiple factors including the balance between the risk of
anemia and the risk of RBC transfusion, existing patient comorbidities, and medical and surgical exposures. The transfusion thresholds recommended by current guidelines vary for medical and surgical patient populations. Guidelines suggesting specific transfusion thresholds for different patient populations should be viewed as a starting point for making an informed decision about RBC transfusion. Alternatives to transfusion (i.e., patient blood management),
biomarkers of
anemia-induced tissue
hypoxia, and transfusion alternatives should continue to be evaluated in large RCTs, with the goal of improving event-free survival in
critically ill and perioperative patients.