Characteristics Associated With Transfusion Reaction Alerts At An Academic Medical Center
Authors: Henegan John Clark , Asfour Mohamed Ayman 
Published: October 2019

Introduction
An immediate transfusion reaction may be suspected in a patient experiencing new or a change in symptoms while receiving blood products. The patient's acute clinical change often warrants halting the transfusion and alerting the blood bank to the possibility of a transfusion reaction. In an effort to better understand the patient, transfusion, and clinical characteristics of these acute events we reviewed all of the transfusion reaction alerts submitted over one year at an academic medical center.

Methods
Transfusion reaction alerts submitted for the previous year to the blood bank at an academic medical center were compiled. Delayed serologic reactions were excluded in an effort to focus on immediate transfusion reactions. The charts associated with these events (n=48) were reviewed and details regarding patient, transfusion component, and clinical characteristics were recorded. In addition, the reaction's final classification after review by an experienced blood bank pathologist was noted.

Results
Of the 48 transfusion reaction alerts, 56% involved a patient with any type of previously documented allergy.
Event notes associated with the suspected transfusion reaction indicated that:
o 51% involved a dermatologic symptom (e.g. edema, erythema, maculopapular changes, pruritus)
o 32% included a respiratory symptom (e.g. dyspnea, wheezing)
o 16% included a constitutional symptom (e.g. chills, fever, rigors, diaphoresis, pain)
o 16% included a neurological symptom (e.g. dizziness, lethargy, agitation)
There was no concordance between the five alerted reactions that found new onset, post transfusion hemoglobinemia and the seven alerted reactions that demonstrated new onset, post transfusion hemogloburia.
Significant findings included
o Persons < 18 years of age were more likely to have an alert that involved a dermatologic symptom than another type of symptom (RR: 2.8, 1.6-4.2, p= 0.001).
o IR APH platelets were more likely to have an alert that involved a dermatologic symptom than another type of symptom (RR: 2.56, 1.4-4.8, p=0.003).
o A temperature increase of > 2 °F had:
µ A significant increased associated with reactions classified as febrile nonhemolytic reactions (RR: 4.1, 1.6-10.4, p=0.003)
µ A significant decreased association with a reactions classified as allergic reactions (RR: 0.22, 0.05-0.90, p=0.03).
After review by an experienced blood bank pathologist, no acute hemolytic transfusion reactions were found to have occurred in the past year.

Conclusions
This review of immediate transfusion reactions has a number of significant limitations including:
· Being a retrospective review from a single center
· Involving a small sample size
· Lack of any acute hemolytic transfusion reactions as determined by an experienced blood bank pathologist
· Relying on univariate analysis to detect significant findings
· Lack of a formal method to detect ascertainment bias
Despite these limitations, these findings may spark future work related to:
· The prevalence of documented allergies (56%) in patients with an acute transfusion reaction alert is significantly higher than a previously reported rate of 21% of hospitalized patients with documented allergies of any type (Gonzales-Gregori et al. 2012).
· The concordance between post transfusion hemoglobinuria and hemoglobinemia in transfusion reactions as there was no concordance between these two laboratory tests in this study.
· Validating that a recorded temperature rise of > 2 F can be used at the bedside to determine if an immediate transfusion reaction is a febrile nonhemolytic reaction and not an allergic reaction.

Disclosures:
No relevant conflicts of interest to declare.