High prevalence of non-dipping patterns among black Africans with uncontrolled hypertension: a secondary analysis of the CREOLE trial

Background

Dipping of blood pressure (BP) at night is a normal physiological phenomenon. However, a non-dipping pattern is associated with hypertension mediated organ damage, secondary forms of hypertension and poorer long-term outcome. Identifying a non-dipping pattern may be useful in assessing risk, aiding the decision to investigate for secondary causes, initiating treatment, assisting decisions on choice and timing of anti-hypertensive therapy, and intensifying salt restriction.

Objectives

To estimate the prevalence and factors associated with non-dipping pattern and determine the effect of three 6-months anti-hypertensive regimens on the dipping pattern among Black African hypertensive patients.

Methods

This was a secondary analysis of the CREOLE Study which was a randomized, single blind, three-group trial conducted in 10 sites in 6 Sub-Saharan African countries. The participants were 721 Black African patients, aged between 30 and 79 years, with uncontrolled hypertension and a baseline 24-hour ambulatory blood pressure monitoring (ABPM). Dipping was calculated from the average day and average night systolic blood pressure measures.

Results

The prevalence of non-dipping pattern was 78% (564 of 721). Factors that were independently associated with non-dipping were: serum sodium >140mmol/l (OR=1.72, 95% CI: 1.17–2.51, p-value 0.005), a higher office systolic BP (OR=1.03, 95% CI: 1.01–1.05, p-value 0.003) and a lower office diastolic BP (OR=0.97, 95% CI: 0.95–0.99, p-value 0.03). Treatment allocation did not change dipping status at 6 months (McNemar's χ2 0.71, p-value 0.40).

Conclusion

There was a high prevalence of non-dipping among Black Africans with uncontrolled hypertension. ABPM should be considered more routinely in Black Africans with uncontrolled hypertension, if resources permit, to help personalise therapy. Further research is needed to understand the mechanisms and causes of non-dipping pattern and if targeting night-time BP improves clinical outcomes.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Fogarty International Center and the National Institutes of Health of the United States of America Figure 1

Development of the roadmap and guidelines for the prevention and management of high blood pressure in Africa: Proceedings of the PASCAR Hypertension Task Force meeting: Nairobi, Kenya, 27 October 2014

Africa has one of the fastest growing economies in the world. The economic changes are associated with a health transition characterised by a rise in cardiovascular risk factors and complications, which tend to affect the African population at their age of maximum productivity. Recent data from Africa have highlighted the increasing importance of high blood pressure in this region of the world. This condition is largely underdiagnosed and poorly treated, and therefore leads to stroke, renal and heart failure, and death. Henceforth, African countries are taking steps to develop relevant policies and programmes to address the issue of blood pressure and other cardiovascular risk factors in response to a call by the World Health Organisation (WHO) to reduce premature deaths from non-communicable diseases (NCDs) by 25% by the year 2025 (25 × 25). The World Heart Federation (WHF) has developed a roadmap for global implementation of the prevention and management of raised blood pressure using a health system approach to help realise the 25 × 25 goal set by the WHO. As the leading continental organisation of cardiovascular professionals, the Pan-African Society of Cardiology (PASCAR) aims to contextualise the roadmap framework of the WHF to the African continent through the PASCAR Taskforce on Hypertension. The Taskforce held a workshop in Kenya on 27 October 2014 to discuss a process by which effective prevention and control of hypertension in Africa may be achieved. It was agreed that a set of clinical guidelines for the management of hypertension are needed in Africa. The ultimate goal of this work is to develop a roadmap for implementation of the prevention and management of hypertension in Africa under the auspices of the WHF.