Cardiovascular disease risk among sub-Saharan African migrant and home populations

Abstract

Urbanization and migration have been increasing in the last few decades and have been associated with rising levels of cardiovascular diseases (CVD) and its risk factors in urban populations in low-and middle-income countries and migrant populations in high income countries. Transitioning of societies and resulting changes in lifestyle is a major driving force but key specific factors are not known. The aim of this thesis was to assess CVD risk among sub-Saharan African populations by assessing (i) the knowledge of and perception of CVD risk (ii) the differences in the burden of CVD risk and associated risk factors and (iii) explore CVD risk prediction and determinants of CVD mortality in sub-Saharan Africa (SSA). First, despite the high burden of CVD among sub-Saharan African populations, knowledge of CVD risk was very low. In a systematic review, less than half of study participants from included studies had good knowledge of CVDs and/or risk factors. Low knowledge of CVDs, risk factors and clinical symptoms is strongly associated with the low levels of educational attainment and rural residency. Second, we found that CVD risk vary according to geographical contexts. Compared to rural Ghana, CVD risk was significantly increased for Ghanaian men living in Europe. Additionally, this risk increased with duration of stay in Europe. Third, we observed contextual differences in risk factors of CVD and their resultant association with CVD risk. We found an inverse association between a ‘mixed’ and ‘rice, pasta, meat and fish’ DP and CVD risk among Ghanaian populations in urban Ghana whereas a ‘roots, tubers and plantain’ DP was directly associated with increased 10-year risk CVD risk in rural Ghana. Psychosocial stress was also associated with CVD risk among Ghanaian populations. Recent negative life events were associated with a high estimated CVD risk in non-migrants while higher levels of perceived discrimination were associated with a high estimated CVD risk in migrants. Sitting height, a marker of early life exposure was also associated with CVD risk. Currently, screening tools for the management of CVD are less available in SSA. However, we observed that current CVD risk algorithms, developed on different populations might not appropriate estimate CVD risk for the SSA population. We found that CVD prediction with the same algorithm differs for the migrant and home populations. Finally, based on a 10-year follow data on South African population, age, smoking, hypertension and HIV status were found to be major determinants of CVD mortality. This suggests that together with previously established risk factors for CVD, HIV infection could be a potentially important risk factor for CVD risk prediction in this population. In conclusion, this thesis recommended the implementation of effective policy measures and increased commitment to improving public awareness and effective surveillance mechanisms in SSA. However, the socio-cultural context should be taken into consideration and used to address knowledge gaps. Preventive measures for CVD among migrants should take into consideration ethnic differences, as well as address the challenges in access to healthcare among minority populations.