In a report published online by JAMA, Jeffrey L. Carson, M.D., of Rutgers Robert Wood Johnson Medical School, New Brunswick, N.J., and colleagues provide recommendations for the AABB (previously known as the American Association of Blood Banks) for the target hemoglobin level for red blood cell (RBC) transfusion among hospitalized adult patients who are hemodynamically stable and the length of time RBCs should be stored prior to transfusion.
More than 100 million units of blood are collected worldwide each year, and approximately 13 million RBC units are collected in the United States, yet the indication for RBC transfusion and the optimal length of RBC storage prior to transfusion are uncertain. For RBC transfusion thresholds, the authors summarized and analyzed the results of 31 randomized clinical trials (RCTs) that included 12,587 participants and compared restrictive thresholds (transfusion not indicated until the hemoglobin level is 7-8 g/dl) with liberal thresholds (transfusion not indicated until the hemoglobin level is 9-10 g/dl). The summary estimates across trials demonstrated that restrictive RBC transfusion thresholds were not associated with higher rates of adverse clinical outcomes. For RBC storage duration, 13 RCTs included 5,515 participants randomly allocated to receive fresher blood or standard-issue blood. These RCTs demonstrated that fresher blood did not improve clinical outcomes.
Summary of Findings
It is good practice to consider the hemoglobin level, the overall clinical context, patient preferences, and alternative therapies when making transfusion decisions regarding an individual patient. Recommendation 1: a restrictive RBC transfusion threshold in which the transfusion is not indicated until the hemoglobin level is 7 g/dl is recommended for hospitalized adult patients who are hemodynamically stable, including critically ill patients, rather than when the hemoglobin level is 10 g/dl (strong recommendation, moderate quality evidence).
A restrictive RBC transfusion threshold of 8 g/dl is recommended for patients undergoing orthopedic surgery, cardiac surgery, and those with preexisting cardiovascular disease (strong recommendation, moderate quality evidence). The restrictive transfusion threshold of 7 g/dl is likely comparable with 8 g/dl, but RCT evidence is not available for all patient categories. These recommendations do not apply to patients with acute coronary syndrome, severe thrombocytopenia (patients treated for hematological or oncological reasons who are at risk of bleeding), and chronic transfusion-dependent anemia (not recommended due to insufficient evidence).
Recommendation 2: patients, including neonates, should receive RBC units selected at any point within their licensed dating period (standard issue) rather than limiting patients to transfusion of only fresh (storage length: <10 days) RBC units (strong recommendation, moderate quality evidence).
"Transfusion is a common therapeutic intervention for which there is considerable variation in clinical practice. If clinicians continue to adopt a restrictive transfusion strategy of 7 g/dl to 8 g/dl, the number of RBC transfusions would continue to decrease. In addition, standard practice should be to initiate a transfusion with 1 unit of blood rather than 2 units. This would have potentially important implications for the use of blood transfusions and minimize the risks of infectious and noninfectious complications," the authors write.
"Research in RBC transfusion medicine has significantly advanced the science in recent years and provides high-quality evidence to inform guidelines. A restrictive transfusion threshold is safe in most clinical settings and the current blood banking practices of using standard-issue blood should be continued."
(doi:10.1001/jama.2016.9185; the study is available pre-embargo to the media at the For the Media website)
Editor's Note: Support for guideline development was provided by the AABB. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, etc.