Patient Care

When to Order Red Blood Cell Transfusion for Patients with Anemia


 

Life-threatening transfusion reactions occur in approximately seven per million transfused blood components, and transfusion-associated circulatory overload (TACO) can develop in one in 100 transfusions.1

Background

Hospitalists commonly order red blood cell (RBC) transfusion as a therapy for patients with anemia resulting from a variety of clinical conditions. There has been lack of consensus on when to transfuse, because patients with anemia frequently have multiple co-morbidities, including coronary artery disease and congestive heart failure, which may influence their ability to tolerate a potentially ischemic state related to anemia or to accommodate volume fluctuations related to transfusion.

Furthermore, RBC transfusions are not without inherent risk. Life-threatening transfusion reactions occur in approximately seven per million transfused blood components, and transfusion-associated circulatory overload (TACO) can develop in one in 100 transfusions.1

Recently published guidelines provide recommendations for management of hemodynamically stable adults with anemia.

Guideline Update

The AABB published guidelines in the Annals of Internal Medicine in 2012 addressing RBC transfusion thresholds.1 The updated guideline makes a recommendation that clinicians utilize a restrictive transfusion strategy. Transfusion is strongly recommended for ICU patients with hemoglobin ≤7g/dL. In post-operative surgical patients and for post-operative patients with symptomatic anemia, transfusion is recommended for hemoglobin ≤8g/dL. The authors also made a weak recommendation to transfuse for hemoglobin ≤8g/dL or for symptoms in hospitalized hemodynamically stable patients with preexisting cardiovascular disease.

These recommendations draw from past literature, along with two more recent trials examining liberal or restrictive transfusion thresholds. The newer trials increased the total number of patients studied by nearly one third compared with prior reviews.2,3 The authors also incorporated recently published systematic reviews in their analysis.

Although the definition of a restrictive transfusion threshold varied across trials, including hemoglobin ≤7g/dL and ≤8g/dL, the authors used the pooled data to provide several recommendations in the new guideline. Of note, the pooled data was underpowered to detect up to a twofold increase in risk of myocardial infarction in patients in the restrictive strategy group.1

There were insufficient data for the authors to recommend for or against a restrictive transfusion strategy in patients with acute coronary syndrome, based on very low quality evidence.

Finally, the authors recommended that symptoms and hemoglobin level should both be used in determining transfusion criteria, based on low quality of evidence.

Analysis

The current AABB guidelines have two primary differences from earlier guidelines. First, the AABB authors used GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) methodology to formalize evidence-based practice in their analysis of the literature. The authors purposely used the GRADE methodology to systematically evaluate the quality of the evidence base and explicitly state the strength of the recommendation for a particular transfusion threshold.4

Second, the AABB guidelines incorporated data from the more recently published FOCUS (Functional Outcomes in Cardiovascular patients Undergoing Surgical repair of hip fracture) and TRACS (Transfusion Requirements After Cardiac Surgery) trials, resulting in a stronger recommendation supporting the use of a restrictive transfusion strategy in non-ICU and post-operative patients. The findings of the FOCUS trial are especially applicable to hospitalists, because many patients who undergo hip fracture repair are directly cared for or are co-managed by hospitalists.

The current guidelines built upon previous guidelines that advocated a restrictive strategy (hemoglobin ≤7g/dL) in hemodynamically stable, critically ill adult patients.5 In general, restrictive transfusion strategy led to nearly 40% fewer patients receiving transfusion compared with the use of a liberal transfusion strategy.1 No additional harm to patients was evidenced in the restrictive transfusion group, though the trials were not designed to answer this question; moreover, there was no statistically significant difference in mortality or functional outcome between the two groups.

The authors of the current AABB guidelines recognized the importance of replicating the current findings in a more diverse patient population. An area where further study is indicated is in the use of specific transfusion thresholds in patients with acute coronary syndrome. These guidelines did not clarify whether or not there is a physiologic difference between use of different restrictive transfusion thresholds such as <8g/dL and <7g/dL.

The authors of the AABB guidelines also commented that performing a future trial to compare RBC transfusion for symptoms vs. hemoglobin “trigger” would be useful; however, they recognized that this may not be feasible due to the need to blind providers in the trial to hemoglobin values. Various society guidelines currently call for different transfusion thresholds or do not make a specific recommendation at all.1

Key Takeaways for Hospitalists

For the vast majority of medical patients, hospitalists can safely use a restrictive RBC transfusion threshold (≤7g/dL or ≤8g/dL), which can lead to a significant decrease in RBC transfusions without adversely affecting overall mortality.


Drs. Bortinger and Carbo are hospitalists at Beth Israel Deaconess Medical Center in Boston.

References

  1. Carson JL, Grossman BJ, Kleinman S, et al. Red blood cell transfusion: a clinical practice guideline from the AABB. Ann Inter Med. 2012;157(1):49-58.
  2. Carson AL, Terrin ML, Noveck H, et al. Liberal or restrictive transfusion in high-risk patients after hip surgery. N Engl J Med. 2011;367(26):2453-2462.
  3. Hajjar LA, Vincent JL, Galas FR, et al. Transfusion requirements after cardiac surgery: the TRACS randomized controlled trial. JAMA. 2010;304(14):1559-1567.
  4. Carson JL, Carless PA, Herbert PC. Transfusion threshold and other strategies for guiding allogenic red blood cell transfusion. Cochrane Database Syst Rev. 2012;CD002042.
  5. Napolitano LM, Kurek S, Luchette FA, et al. Clinical practice guideline: red blood cell transfusion in adult trauma and critical care. Crit Care Med. 2009;37(12):3124-3157.

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