Abstract
Although the ABO and RhD blood groups systems are the most widely known and recognised there is very little known regarding its relation to ethnicity in South Africa. The purpose of this study is to address the lack of scientific information regarding the distribution of the ABO and RhD blood groups in the various ethnic communities in the Republic of South Africa (RSA). There is currently no published scientific data on the distribution of these blood groups with the last studies being conducted in the 1900’s.
This study aimed to firstly establish the distribution of the ABO and RhD blood groups for South Africa and thereafter in the various ethnic communities in the provinces of South Africa. A comparison was finally drawn between the provinces regarding the distribution of the ABO and RhD blood types as well as various other variables such as age, ethnicity and gender. The conclusions from these were compared to the known distribution of the blood group systems to similar populations in the rest of Africa and globally.
The data of the blood of first-time whole blood donors, which was collected between January 2018 and December 2019 at various fixed and mobile blood donation clinics of the South African National Blood Service (SANBS) and the Western Cape Blood Service (WCBS)in South Africa was used in this retrospective study. The samples from the donations were analysed by these institutions and stored in data banks of the SANBS and the WCBS. This data was requested by the researcher and cleaned before being compared and analysed for the given outcomes. The analysis was performed using the IBM Statistical Package for Social Sciences (SPSS) software program version 28.0.1.0 (142).
The information for each data set was categorised and coded according to gender, stratified age, race/ethnicity province and blood groups and were presented in tables and graphs.
The non-parametric Kruskal-Wallis test was used to determine if there were any significant differences between the ABO and RhD blood types for the different racial/ethnic groups. The Mann-Whitney test was used if a significant difference is
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found to describe the significance of the variations between ABO and RhD blood types for the different racial/ethnic groups for the RSA. The observed frequencies and cross-tabulation were found to be statistically significant at the p-value of < 0.001. This enabled grouping of the data into racial/ethnic groups helping to determine the distribution and frequencies of the blood types of each racial/ethnic group, age group and gender. From the results of the study, for the ABO and RhD blood types, it was possible to make interprovincial comparisons, as well as comparisons to other countries in Africa and globally.
This study included 252 304 first-time donors who passed the medical self-assessment and were deemed healthy through a mini medical evaluation performed prior to the donation of whole blood. Samples were taken and tested at the donation testing laboratories of the SANBS and WCBS where data are stored in the databases.
The study found most first-time donors recruited by the SANBS and WCBS were female (58.3%). The largest group recruited by the SANBS and WCBS were Black (57%) which was due to the recruitment drives of the blood services to recruit the previously disadvantaged groups. It was found that the largest population of donors who were recruited by the SANBS and WCBS were younger than 25. This was expected as the blood services prioritise recruiting donors of a young age from schools and tertiary institutions.
The ABO and RhD distribution for South Africa were consistent with those found globally with group O being 47.5%, group A being 31.9%, group B being 17.6% and group AB being 4.9%. The results showed that 93.2% of the first-time donors were RhD positive while 6.8% were RhD negative. Further analysis indicated that the descending frequency of the ABO and RhD as O Positive (42.5%), A Positive (29.6%), B Positive (16.6%), AB Positive (4.6%), O Negative (3.2%), A Negative (2.3%), B Negative (1.0%) and AB Negative (0.3%).
The comparison of data for the ABO and RhD blood types for the different racial/ethnic groups in the provinces indicated that for the Indian/Asian group the percentages for blood type A were noticeably lower than those for the combined racial/ethnic groups in most of the provinces except for the Northen Cape, while the distribution curve for
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the B blood type was well above those for the combined racial/ethnic groups in each province and the RSA. Furthermore, the general percentages for all blood types of the Black first-time donors were similar to those for the combined racial/ethnic groups in each province and the RSA. In the White population the percentage of blood type A were significantly higher than those of the combined racial/ethnic groups for each of the provinces and the RSA, while for blood type B and AB the percentages were significantly lower than those for the combined racial/ethnic groups in each of the provinces and the RSA. However, the distribution for blood types B, AB and O for the Coloureds differs from those for the combined racial/ethnic groups in each province and the RSA, however, for the distribution for the A blood type follows the trend for the provinces and the RSA. It is worth noting that this could be due to the Coloureds being a multiracial ethnic group.
The ABO and RhD breakdown per racial/ethnic group showed that the Group O had the greatest frequency in the Black population, the group A was found in the White population, the group B as well as AB in the Indian/Asian population. The Coloured population did not show any outstanding blood type however all the values fall within the ranges of the three other racial/ethnic groups. Except for the Coloured donors, all the other groups could be compared to populations found within Africa and globally where similarities can be drawn with the blood groups. The Coloured population is unique to South Africa and therefore cannot be compared globally.
The findings of this study provided valuable information regarding the ABO and RhD blood group distribution amongst and between the various racial/ethnic groups in South Africa and will be made available to the SANBS and WCBS. The findings will be presented at applicable scientific conferences and published. These results contribute to the international knowledge about the blood type distribution as well as assist the blood transfusion organisations in the collection and distribution of this precious life-giving resource. It is envisaged that the knowledge of the prevalence of the ABO blood types in different racial/ethnic groups will also optimise diagnosis and treating diseases.