ABO blood groups and cardiovascular disease and its risk in continental Africans and people of African ancestry: A systematic review.

BACKGROUND: Cardiovascular disease (CVD) remains a global health challenge and contributes substantially to mortality burden in sub-Saharan Africa (SSA) in particular. Several factors, including particular blood group types in the ABO system, have been associated with CVD risk. However, the direction of the association of ABO blood groups with CVD remains controversial. This review looked at the studies that investigated the association of ABO blood groups and CVD and its risk in SSA and people of African ancestry. METHODS: The review included all observational studies that investigated ABO blood groups and their association with CVD and CVD risk in Africans and people of African descent and were published in English between 1960 and 2023. The data were extracted from Pubmed, Google Scholar, ScienceDirect, Web of Science, Scopus, African Wide and Medline. A total of 24 publications were reviewed following the inclusion criteria. The protocol for this systematic review was registered with PROSPERO (ID#: CRD42023495721). RESULTS: A total of 24 studies were included in the review with most of them being cross-sectional in design. The mean age of participants was 44 years with an age range of 1-89 years. The most common blood group in SSA was blood group O. The review showed that 11 out of the 24 studies indicated non-O groups association with CVD and CVD risk and 4 studies indicated blood group O association with CVD risk. The most common CVD risk markers studied were body mass index (BMI) and blood pressure (BP). The CVDs investigated were ischaemic disease, intracranial aneurysm, peripheral artery disease and coronary artery disease. CONCLUSION: There is no conclusive evidence showing a particular blood group, in the ABO system, being cardioprotective or more susceptible to CVD risk. The varying ABO associations with CVD risk among Africans and African ancestry underscore the importance of targeted and localised interventions aimed at curbing CVD against the backdrop of ABO profiling.