CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 5, November/December 2023 AFRICA 315 (2) high salt consumption by SSA patients, especially of middle age, such as in the reported populations,55 and (3) treatment affordability for patients.56 In the CREOLE randomised trial, where treatment were provided free of charge to patients, CCB appeared to be the most effective BP-lowering medicines.57 Treatment availability was also an important determinant of BP control but Rockers et al. and Geldsetzer et al. showed that without public health policies, BP control could not be achieved.58,59 Our review was complementary of the review by Seeley et al.5 We included only observational studies to provide data from real-world settings, whereas the review by Seeley et al. included controlled trials, therefore showing that CCB were the most effective agent to reduce BP in patients from SSA. This was not the picture we got from our analysis of observational studies reflecting more clinical practice in these countries.5 The discrepancy between the results may also be explained by the difference in countries studied. Seeley et al. included a smaller number of Nigerian studies and a larger number of South African studies. This difference may reflect a differential access to the different drug classes in SSA countries. It may also relate to the perceived confidence to the quality, efficacy and safety of the most prescribed antihypertensive drug classes by treating physicians. We believe that this difference does not reflect on aggressive marketing campaigns by pharmaceutical industries since all the drug classes are now generic drugs. English-speaking countries were the most represented countries in our review [Nigeria (n = 14), Ethiopia (n = 4), South Africa (n = 2) and Kenya (n = 2)]. The lack of publications from western Sub-Saharan countries suggests a geographical inequity in access to English publications since English is currently used among physicians. Of the 30 articles included, 29 (96.6%) had at least one author affiliated to an African institution, suggesting the involvement of African physicians is improving the management of hypertension in their respective countries. Authorship representation and positioning provide one method of measuring African participation and leadership in research, as well as the possibility for Africans to negotiate decision-making in collaborative research performed in their countries.60 Only one of the 30 studies included had an overall risk of bias rating of good. This may show a lack of quality in the study methodology. Therefore, the quality of reporting was heterogeneous and items regarding the methods, particularly, were not completely reported. No study included in the review was multinational, and only three studies were multicentre. The studies included may not be representative enough of antihypertensive strategies employed in SSA and there is a significant publication barrier for resource-constrained institutions.5 Limitations This systematic review had some limitations. Data reporting was incomplete because we did not contact the authors. The reference list of articles included was not scanned and unpublished literature as well as grey literature were not reviewed. We restricted our search to begin in 2003. This choice was based on convenience as it was the year of publication of guidelines by ethnicity (black/non-black) in major guidelines of the worldwide society (American and European society). Our research strategy excluded articles where studies were not conducted exclusively in a SSA country. In these large multinational studies, details of data by African countries were not available.61,62 In this study, Nigerian patients were over represented: 40.7% compared to other countries. Indeed, some explanations could be discussed, such as Nigeria is an English-speaking country that publishes many studies in this field. Two studies included in the systematic review were from the same team (Ysuff et al.18) and were published closely. We could not exclude a possible overlap in terms of enrolled patients in these two studies, even if numbers and proportions were different. The settings of the majority of studies were in tertiary-care centres. Even though ‘special populations’ (secondary hypertensives) were excluded, the lack of data regarding the lower level of care does not allow for drawing conclusions regarding the therapeutic strategies most commonly used, given that a large proportion of patients receive treatment for hypertension at a lower level of care. The populations at tertiary level are most likely not the same as those accessing lower levels, and prescription patterns might be very different (in various countries some classes of drugs are not available at primary levels of care). Moreover, they assessed mostly urban areas and this is hardly generalisable to all of SSA. We excluded studies where the principal inclusion criterion was stroke. The burden of stroke is high in SSA and few data are available on long-term mortality. However, hypertension remains the most important modifiable risk factor for stroke in Africa. A new study focusing on stroke and hypertension is necessary. Adherence to medication was assessed in only three studies and could be an important element in explaining poor BP control despite a majority of patients being on two and three agents. We possibly underestimated interactions between drug regimens and co-morbidities that may contribute to antihypertensive drug choice, drug dosage and potential resistant hypertension. Conclusion Our review summarises antihypertensive strategies employed in SSA to achieve BP control. Our analysis provides the opportunity to extend knowledge on the effectiveness of antihypertensive strategies in SSA. Our systematic review showed that there are likely too many patients on monotherapy. Multicentre and multinational studies in rural and urban cities are needed to ensure international guidelines actually do improve outcomes in low- and middle-income countries. Studies should be designed with attention to methodology to collect generalisable data to develop hypertension public health policies. Key messages • Few comprehensive syntheses of pharmacotherapy used to manage hypertension in SSA are available. • Too few studies had a good overall rating risk of bias, and there is a significant publication barrier for resource-constrained institutions. • Multicentre and multinational studies in rural and urban cities are needed, and studies should be designed with attention to methodology. The authors acknowledge Dr Carole Ratsimbazafy for her informed advice in the writing of this systematic review. The study was exclusively supported by public grants from INSERM (Institut national de la Santé et de la Recherche Médicale) and AP-HP (Assistance Publique – Hôpitaux de Paris), Paris Descartes University.
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