Parsimonious blood use and lower transfusion triggers: What is the evidence?
ABSTRACT
Evidence supports a parsimonious approach to blood use for managing anemia, contrasting with the long-standing practice of blood transfusion targeting arbitrary hemoglobin levels. Hemodilution studies have demonstrated that humans can tolerate anemia. The cumulative data have confirmed and validated the safety of a conservative approach to transfusion. This has translated into formal national guidelines for blood transfusion as well as patient safety and quality markers supporting blood management stewardship to minimize unnecessary use of blood products.
KEY POINTS
- In critical care patients, transfusion should be considered when the hemoglobin concentration reaches 7 g/dL or less.
- In postoperative patients and hospitalized patients with preexisting cardiovascular disease, transfusion should be considered at a hemoglobin concentration of 8 g/dL or less or for symptoms such as chest pain, orthostatic hypotension, or tachycardia unresponsive to fluid resuscitation, or heart failure.
- Consider both the hemoglobin concentration and the symptoms when deciding whether to give a patient a transfusion.
Noninfectious complications
Transfusion-associated circulatory overload occurs in 4% to 6% of patients who receive a transfusion. Therefore, circulatory overload is a greater danger from transfusion than infection is.42
Febrile nonhemolytic transfusion reactions occur in 1.1% of patients with prestorage leukoreduction.
Transfusion-associated acute lung injury occurs in 0.8 per 10,000 blood components transfused.
Errors associated with blood transfusion include, in decreasing order of frequency, transfusion of the wrong blood component, handling and storage errors, inappropriate administration of anti-D immunoglobulin, and avoidable, delayed, or insufficient transfusions.43
Surgery and condition-specific complications of red blood cell transfusion
Cardiovascular surgery. Transfusion is associated with a higher risk of postoperative stroke, respiratory failure, acute respiratory distress syndrome, prolonged intubation time, reintubation, in-hospital death, sepsis, and longer postoperative length of stay.44
Malignancy. The use of blood in this setting has been found to be an independent predictor of recurrence, decreased survival, and increased risk of lymphoplasmacytic and marginal-zone lymphomas.44–47
Vascular, orthopedic, and other surgeries. Transfusion is associated with a higher risk of death, thromboembolic events, acute kidney injury, death, composite morbidity, reoperation, sepsis, and pulmonary complications.44
ST-segment elevation myocardial infarction, sepsis, and intensive care unit admissions. Transfusion is associated with an increased risk of rebleeding, death, and secondary infections.44
COST OF RED BLOOD CELL TRANSFUSION
Up to 85 million units of red blood cells are transfused per year worldwide, 15 million of them in the United States.42 At our hospital in 2013, 1 unit of leukocyte-reduced red blood cells cost $957.27, which included the costs of acquisition, processing, banking, patient testing, administration, and monitoring.
The Premier Healthcare Alliance48 analyzed data from 7.4 million discharges from 464 hospitals between April 2011 and March 2012. Blood use varied significantly among hospitals, and the hospitals in the lowest quartile of blood use had better patient outcomes. If all the hospitals used as little blood as those in the lowest quartile and had outcomes as good, blood product use would be reduced by 802,716 units, with savings of up to $165 million annually.
In addition to the economic cost of blood transfusion, the clinician must be aware of the cost in terms of comorbidities caused by unnecessary blood transfusion.49,50
RECOMMENDATIONS FROM THE AABB
In view of all the current compelling evidence, a restrictive approach to transfusion is the single best strategy to minimize adverse outcomes.51 Below, we outline the current recommendations from the AABB (formerly the American Association of Blood Banks),42 which are similar to the national clinical guideline on blood transfusion in the United Kingdom,52 and have recently been updated, confirming the initial recommendations.53
In critical care patients, transfusion should be considered if the hemoglobin concentration is 7 g/dL or less.
In postoperative patients and hospitalized patients with preexisting cardiovascular disease, transfusion should be considered if the hemoglobin concentration is 8 g/dL or less or if the patient has signs or symptoms of anemia such as chest pain, orthostatic hypotension, or tachycardia unresponsive to fluid resuscitation, or heart failure.
In hemodynamically stable patients with acute coronary syndrome, there is not enough evidence to allow a formal recommendation for or against a liberal or restrictive transfusion threshold.
Consider both the hemoglobin concentration and the symptoms when deciding whether to give a transfusion. This recommendation is shared by a National Institutes of Health consensus conference,54 which indicates that multiple factors related to the patient’s clinical status and oxygen delivery should be considered before deciding to transfuse red blood cells.
The Society of Hospital Medicine55 and the American Society of Hematology56 concur with a parsimonious approach to blood use in their Choosing Wisely campaigns. The American Society of Hematology recommends that if transfusion of red blood cells is necessary, the minimum number of units should be given that relieve the symptoms of anemia or achieve a safe hemoglobin range (7–8 g/dL in stable noncardiac inpatients).57
New electronic tools can monitor the ordering and use of blood products in real time and can identify the hemoglobin level used as the trigger for transfusion. They also provide data on blood use by physician, hospital, and department. These tools can reveal current practice at a glance and allow sharing of best practices among peers and institutions.52
CONSIDER TRANSFUSION FOR HEMOGLOBIN BELOW 7 G/DL
The routine use of blood has come under scrutiny, given its association with increased healthcare costs and morbidity. The accepted practice in stable medical patients is a restrictive threshold approach for blood transfusion, which is to consider (not necessarily give) a single unit of packed red blood cells for a hemoglobin less than 7 g/dL.
However, studies in acute coronary syndrome patients and postoperative cardiac surgery patients have not shown the restrictive threshold to be superior to a liberal threshold in terms of outcomes and costs. This variability suggests the need for further studies to determine the best course of action in different patient subpopulations (eg, surgical, oncologic, trauma, critical illness).
Also, a limitation of most of the clinical studies was that only the hemoglobin concentration was used as a marker of anemia, with no strict assessment of changes in red cell mass with transfusion.
Despite the variability in certain populations, the overall weight of current evidence favors a restrictive approach to blood transfusion (hemoglobin < 7 g/dL), although perhaps in patients who have active coronary disease or are undergoing cardiac surgery, a more lenient threshold (< 8 g/dL) for transfusion should be considered.
