Australian Red Cross Lifeblood Sydney, New South Wales, Australia
Background/Case Studies: The first national study on ABO RhD prevalence in Australia was recently conducted. It showed that the proportion of RhD positive individuals has increased by 5% in alignment with the changing demographics of the community. The proportion of B and AB blood groups had also increased. These blood groups are more prevalent in people from South East Asia, China and India, countries from which Australia has had increased immigration. Contemporary data on the prevalence of other clinically relevant blood groups in Australians has not been reported. This study aimed to analyse the proportion of Rh(C, c, E, e) blood group phenotypes in Australian blood donors.
Study
Design/Methods: Blood group phenotype data from all blood donors who donated at least once in 2019 were extracted from the National Blood Management System (NBMS) administered by Australian Red Cross Lifeblood. Since 2006, testing for Rh(C, c, E, e) and K blood group phenotypes has been performed on sample from all first-time donors using the PK7300 Automated Microplate System (Beckman Coulter).
Results/Findings: Phenotype data from 477,602 blood donors, including 103,779 (21.7%) first time donors was analysed. Prior to us conducting this analysis the estimated prevalence of the R1R1 (D+C+E-c-e+) phenotype was 17.3%. After analysing the 2019 blood donor data, we found that this had increased to 20.6% and 24.0% in first-time blood donors. Previous estimates of the prevalence of the rr (D-C-E-c+e+) phenotype was 16.4%. After analysing the 2019 blood donor data, we found that the prevalence was 19.8% in the total blood donor panel but was lower (15.2%) in first-time blood donors. There is a higher proportion of B+ donors that have the R1R1 phenotype compared to other ABO RhD blood groups. Conclusions: These results suggest that with the changing demographics of the Australian population, more people in the community are likely to be B+ and have the R1R1 phenotype. This means that if exposed to the c antigen present in rr red blood cell units there is an increased risk of the patient forming anti-c. This may result in an increase in the number of pregnancies requiring assessment for the potential of Haemolytic Disease of the Foetus and Newborn (HDFN) and may also increase the risk of transfusion reactions when RhD negative blood is used in emergency settings. This study indicates that updated analysis of population blood group prevalence by international blood providers can assist in the understanding of supply challenges and the changing requirements for phenotyped red blood cell units. More data is required to understand the impact of exposure to ‘c’ when RhD negative red blood cell units are used in predominantly RhD positive patients.
Importance of research: In 2022, we reported that the proportion of B+ and AB+ individuals had increased in Australia. Reports on the prevalence of other clinically significant blood groups have been limited but using contemporary blood donor data, we found that there has been an increase in B R1R1 (D+C+E-c-e+) individuals who, if exposed to rr (D-C-E-c+e+) red blood cells may form anti-c. Updated analysis of population blood group prevalence can assist in the understanding of phenotype changes and blood supply impact.
