Clinical question: What is a safe target hemoglobin level for patients requiring red blood cell transfusion, and how long can red blood cells be stored prior to transfusion?
Background: The AABB, formerly the American Association of Blood Banks, notes several new, large, rigorous studies on transfusion thresholds were published since their last guideline in 2012. Additionally, there are concerns from initial studies of increased morbidity and mortality with transfusions of red blood cells stored for longer periods of time.
Study design: Systematic review and meta-analysis.
Setting: Summary findings from the AABB clinical transfusion medicine committee.
Synopsis: Thirty-one randomized clinical trials (RCTs) evaluating blood transfusion thresholds were reviewed and analyzed, including 12,587 patients across various clinical scenarios. The authors recommend a restrictive threshold of 7 g/dL for most hospitalized adult patients in the appropriate clinical context. For patients undergoing orthopedic or cardiac surgery, or with cardiovascular disease, a threshold of 8 g/dL is recommended, as it was the threshold used in studies of these patients (though such patients may actually tolerate a lower value).
No recommendations were made for patients with acute coronary syndrome, hematological or oncological disorders, severe thrombocytopenia, or chronic transfusion-dependent anemia given limited data.
To determine a safe period of time for blood storage prior to transfusion, 13 RCTs were reviewed and analyzed. The authors recommend that patients requiring transfusion receive red blood cell units at any period within the standard issue period (less than 42 days), rather than limit transfusion to fresh units (less than 10 days).
Bottom line: A restrictive red blood cell transfusion threshold of 7-8 g/dL is safe in most clinical settings, and there is no advantage to using fresh units as opposed to those stored for the standard period.
Citation: Carson JL, Guyatt G, Heddle NM, et al. Clinical practice guidelines from the AABB..
Dr. Murphy is a clinical instructor at the University of Utah School of Medicine and an academic hospitalist at the University of Utah Hospital.