Understanding the frequency and distribution of RBC alloantibodies and blood groups in Aboriginal* patients 

Understanding the frequency and distribution of RBC alloantibodies and blood groups in Aboriginal* patients  

A retrospective study of 2327 consecutive patients undergoing cardiac surgery at Flinders Medical Centre (FMC) between January 2014 and June 2019 investigated RBC alloantibody prevalence and ABO RhD groups. Of the cohort 588 (25.3%) were from the Northern Territory, and 420 (18.0%) were Aboriginal.   

Aboriginal peoples have high rates of cardiovascular disease, including rheumatic heart disease, with a subset requiring cardiothoracic surgery, such as cardiac valve repair and/or replacement. Between 2016-2020, 95% of patients from the NT undergoing surgery for rheumatic heart disease were Aboriginal.  

Cardiac surgery is associated with high rates of red cell (RBC) transfusion support. RBC alloantibodies can form due to exposure to foreign RBC antigens during transfusion, in which case they are typically clinically significant, IgG type and active at 37°C. Such clinically significant alloantibodies pose a risk of acute or delayed haemolytic transfusion reactions and haemolytic disease of the fetus and newborn (HDFN) in pregnant women if re-exposed to the corresponding RBC antigen. The presence of clinically significant alloantibodies usually necessitates finding antigen-negative donor blood for transfusion. Even non-clinically significant alloantibodies, which are typically IgM type and generally most active at lower thermal amplitudes below 37°C, can lead to delays in finding crossmatch compatible blood for future blood transfusions.  

Aboriginal patients had a higher prevalence of ABO group O (59.8% vs 43.9%) and RhD positive (99.0% vs 83.8%) compared to non-Aboriginal patients. One-hundred-and-eleven patients had 154 RBC alloantibodies, with 57/420 (13.6%) in Aboriginal versus 54/1907 (2.8%) in non-Aboriginal (p<0.0001). There were higher numbers of IgM alloantibodies in Aboriginal patients (59/77, 77%), with Lewis, P1 and M more common. Sixty patients had antibodies detected at time of surgery, 14 NT patients with previously detected alloantibodies, prior to surgery, presented with a negative antibody screen and 37 had new antibodies detected after cardiac surgery.  

The authors highlighted the relevance of the study: “Understanding the frequency and distribution of RBC alloantibodies and blood groups in Aboriginal patients is critical in managing optimal blood donor recruitment, blood supply planning, RBC inventory management, in reducing wastage, and better understanding risks of transfusion and patient informed consent.”  

*The term ‘Aboriginal’ is used respectfully throughout the paper and this article as inclusive of people who identify as First Nations, Aboriginal, Torres Strait Islander or both Aboriginal and Torres Strait Islander peoples and cultures.  

Reference:  

Sinha R, Baker RA, Noutsos T, Perry M, Roxby D. The prevalence of alloantibodies and ABO RhD blood groups in a cohort of Aboriginal and non-Aboriginal cardiac surgery patients from Australia. Transfusion and Apheresis Science 2024;63:103957. https://doi.org/10.1016/j.transci.2024.103957.