Comparison of liberal and restrictive blood transfusion: current insights into clinical outcomes

The aim of this review is to evaluate the evidence of randomized controlled trials and meta-analyses that the current blood transfusion guidelines are based upon. These studies examine the administration of blood to patients where benefits outweigh risks according to the hemoglobin (Hb) level. The guidelines for transfusion policies are based on studies published up to the year 2014 and recommend the restrictive Hb thresholds as applicable to all care environments compared to a more liberal one. Within the past 2 years, the published studies are more targeted on specific settings and disease groups who can tolerate anemia and who cannot. The recent findings raise the possibility that patient outcome is better using a more liberal transfusion policy in patients with cardiovascular disease and in perioperative patients (surgery for abdominal cancer, cardiac surgery, and frail older patients with hip fracture). There are still many ongoing studies reflecting, what this review also suggests, that the evidence of the restrictive limits used on all patients across the board is not usable for clinicians. In the clinic (as in research), it is crucial to have the opportunity to deviate from the guidelines if signs of anemia are present in the patients and to tailor the transfusion strategy to each patient. There is also a lack of evidence on the most optimal transfusion threshold in other cancer categories than abdominal and in the nonoperative old and frail patients. This should be studied in future experimental studies.