University Of Texas Medical Branch Galveston Philadelphia, Pennsylvania, United States
Background/Case Studies: Red blood cell (RBC) antigen frequencies used in calculations to determine the number of donor units to screen for transfusion are universally defined in literature despite the wide ethnic variation in the United States. Through advancement in technology, blood centers now have the ability to screen a large population of blood donors using high throughput molecular assays that may result in a different RBC antigen frequency than what is currently defined.
This study focused on comparing published RBC antigen frequencies to frequencies calculated using molecular assays. The results were used to assess whether the antigen frequencies differed enough to impact the number of units needed to screen in order to find compatible blood for transfusion.
Study
Design/Methods: A retrospective cross-sectional study was performed to determine the frequency of RBC antigens using high throughput molecular assays on 105,082 multi-ethnic blood donors. Thirty-seven (37) RBC antigens were evaluated. The frequency of each antigen in the Caucasian population, using The Blood Bank Antigen FactsBook as reference, was used for the published antigen frequencies.
A one sample t-test using effect size was used to compare the demonstrated frequency of each antigen to the published antigen frequency. Calculations to find one (1) unit for transfusion were performed using both published antigen frequencies and demonstrated antigen frequencies.
Results/Findings: Statistical significance (p < 0.05) was found for all antigens with the exceptions of N and k, with small to moderate effect size reported for each antigen.
The difference in the number of units to screen for transfusion was minimal for each antigen with the exception of the Fyb antigen, which yielded four (4) additional units to be screened when using the frequency from the published literature. It was noted that the calculation of units increased exponentially as the number of units requested increased.
Conclusions: The study supports the finding that there is a significant statistical difference between the published frequency of each antigen and the demonstrated frequency of each antigen.
Analyzing a large quantity of samples can reveal variations in RBC antigen frequencies based on the population studied. As a result, blood centers may opt adjust the number of units recommended for screening to reflect regional antigen frequencies rather than relying on universal frequencies.
