There has been a wealth of information on the prevalence of hypertension on the African continent. A 2007 systematic review by Addo et al. had illustrated the high prevalence of hypertension in numerous African states [12
]. Although our search terms did not include prevalence, this systematic review reveals varied levels of prevalence across countries, a great many of which confirm persisting high rate. In a high prevalence setting like Africa, it is of utmost importance to describe not only the detection rate but also awareness, treatment and control as well as the factors that influence these rates. This would enable the formulation of relevant tailor-made control strategies in order to reduce the complications of uncontrolled hypertension. This systematic review is, to our knowledge, the most comprehensive analysis on awareness, treatment and control on the African continent to date.
Our results show generally low levels of awareness of hypertensive status with North African countries having relatively better levels. The levels in Africa are much lower than those in North America and Europe where temporal reviews have shown an improvement in awareness from twenty years ago when the levels where similar to the level currently seen in Africa to the present rate of over 65% [53
]. Most of this improved awareness has been attributed to rigorous education programs on hypertension after the realization that hypertension was a major player in morbidity and mortality in these countries. Whereas the heterogeneous nature of the designs of the study reviewed here could not allow the establishment of a temporal trend in this review, no improvement was realised in countries that had multiple consecutive studies such as Tanzania. It is possible that similar appreciation of hypertension as leading cause of death would lead to improved education and therefore improved awareness.
The treatment rates found by our review in North Africa were much higher than those found elsewhere on the continent. It is possible that the availability of health insurance in countries such as Tunisia which covers both diagnosis and treatment steers these high levels of treatment. In Massachusetts USA, universal health insurance coverage has led to improved diagnosis and control of hypertension leading to a reduction in hypertension related hospitalisations and deaths [54
]. It is possible that hypertension status will improve in countries aiming to attain universal health coverage such as South Africa. In other parts of Africa, nationalized health insurance remains out of reach. Most Africans pay out-of-pocket for their health expenses, which are supplemented somewhat by a few free services from government and donor organizations which mainly focus on infectious disease treatment with HIV/AIDS control efforts taking a lion’s share of this funding [55
]. This calls for more innovative ways of financing care for chronic non-communicable disease on the continent.
The studies considered in this review revealed generally dismal rates of control of hypertension. The lowest rates of control were seen in Tanzania in studies spanning 10 years. Even in countries that had impressive rates of treatment, control of blood pressure to target remained elusive in many. This means that treatment of hypertension does not guarantee control, the ultimate predictor of outcomes. Several of the included studies from different countries blamed various factors for poor blood pressure control. These can generally be categorised as such as the health-system deficiencies, patients’ non-adherence and the physicians’ inertia in treating hypertension and they seem to be in play on the African continent. For example, the lack of anti-hypertensive medication at health facilities and the long distance to the health facilities reported in some studies are characteristic health system shortcomings hindering the achievement of control [28
]. On the other hand the lack of time and reported competing priorities are classical patient and physician factors adding to the problem [45
Blood pressure in women was generally better controlled than in men in Africa. In two studies in Tanzania and Nigeria, the men were more aware of their status and were more likely to receive treatment. Still, the women achieved better control rates. The issue of gender differences in hypertension has been a subject of intense research. It is now recognised that young men are more likely to develop hypertension than women, a dynamic that has been blamed on androgen mediated abnormalities in pressure natrieusis [56
]. However, large meta-analyses of hypertension treatment trials have failed to document gender differences in response to antihypertensive medication meaning that the poor control of hypertension documented in men is probably due to socio-economic and cultural factors [57
]. In other parts of the world, control of blood pressure seems to be poorer in women. This is possibly because these studies have largely considered elderly men and women [58
]. In our review women of all age groups seemed to have better control. In various studies in the African setting, the women seem to have better health seeking behaviour for chronic disease than men [60
]. It is also possible that women benefit from screening due to more contact with healthcare facilities during the reproductive years [62
]. The men, on the other hand, are less enthusiastic in seeking care. Indeed in one included study from Angola, men reportedly did not pick up their antihypertensive medication because they lacked time [28
]. The finding supports the establishment of gender-specific programs for the treatment and control of blood pressure.
There were certain limitations in this review. The use of one database may have limited the number of articles obtained for the review. However, by searching the PubMed database we limited our search to peer-reviewed sources which offered a firm guarantee that the publications used were appropriate for review [63
As previously mentioned, these studies were heterogeneous in nature which made further analysis difficult. In addition, the cross-sectional nature of the considered studies complicated efforts to discuss the trends in awareness, treatment and control. In Tanzania, frequent studies have been done in the capital Dar es Salaam over time and so we commented on trends [24
]. There is need to carry out surveillance or follow-up cohorts in order to study the trends of hypertension status. A further limitation with most of the reviewed studies was the failure to study the factors that contributed to the current hypertension status on the continent which calls for systematic study of these factors to inform interventions and policy. Other draw-backs included non-random selection of participants in some of the studies [30
] the under-representation of the central African region.