Stroke in Africa: profile, progress, prospects and priorities

Abstract

Stroke is a leading cause of disability, dementia and death worldwide. Approximately 70% of deaths from stroke and 87% of stroke-related disability occur in low-income and middle-income countries. At the turn of the century, the most common diseases in Africa were communicable diseases, whereas non-communicable diseases, including stroke, were considered rare, particularly in sub-Saharan Africa. However, evidence indicates that, today, Africa could have up to 2-3-fold greater rates of stroke incidence and higher stroke prevalence than western Europe and the USA. In Africa, data published within the past decade show that stroke has an annual incidence rate of up to 316 per 100,000, a prevalence of up to 1,460 per 100,000 and a 3-year fatality rate greater than 80%. Moreover, many Africans have a stroke within the fourth to sixth decades of life, with serious implications for the individual, their family and society. This age profile is particularly important as strokes in younger people tend to result in a greater loss of self-worth and socioeconomic productivity than in older individuals. Emerging insights from research into stroke epidemiology, genetics, prevention, care and outcomes offer great prospects for tackling the growing burden of stroke on the continent. In this article, we review the unique profile of stroke in Africa and summarize current knowledge on stroke epidemiology, genetics, prevention, acute care, rehabilitation, outcomes, cost of care and awareness. We also discuss knowledge gaps, emerging priorities and future directions of stroke medicine for the more than 1 billion people who live in Africa.

Fig. 1. Risk factors for stroke in Africa.

a | The population attributable risk associated with 10 potentially modifiable risk factors in the INTERSTROKE study (Africa sub-cohort). The study included 973 case–control pairs of Indigenous Africans from sites in Mozambique, Nigeria, Sudan, South Africa and Uganda. Data from ref. and ref.. b | The population attributable risk associated with 11 potentially modifiable risk factors in the Stroke Investigative Research and Educational Network (SIREN) study. The study included 2,118 case–control pairs of Indigenous Africans from multiple sites across Nigeria and Ghana. Data from ref..

Fig. 2. Effect of race and geography on risk factors for stroke.

Graph shows the frequency of eight risk factors in Indigenous Africans, African Americans and Americans of European descent. Study participants were >55 years of age. The data for this analysis came from 1,928 individuals with stroke who met the selection criteria and consisted of 811 Indigenous Africans recruited into the Stroke Investigative Research and Educational Network (SIREN) study, 452 African Americans and 665 Americans of European descent who were participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. The group of participants of African ancestry had a significantly higher prevalence of hypertension and diabetes, similar frequency of dyslipidaemia and lower prevalence of cardiac disorders than Americans of European descent. However, obesity and lifestyle factors, including smoking, alcohol consumption and physical inactivity, were more prevalent among African Americans and Americans of European descent than Indigenous Africans. These data illustrate the complex interaction between racial (genetic) and geographical (environmental, for example, lifestyle) factors in the neurobiology of stroke. Data from ref..

Fig. 3. A life course approach to factors driving stroke burden in Africa.

The population-level risk factors for stroke change across the lifespan. Here, we summarize the risk factors at each stage of the life course that are driving the increasing burden of stroke in Africa. We also highlight the molecular mechanisms and processes involved in stroke risk at each stage of life. HIV, human immunodeficiency virus.

Fig. 4. Studies on stroke in Africa.

Here, we summarize the published literature on stroke in Africa, from 1999 to November 2020, and including 107 case reports or series, 29 epidemiological studies, 562 clinical studies, 5 clinical trials, 4 international studies, 30 genetic studies, 21 preclinical studies, 136 reviews, 52 letters or editorials, 6 clinical guidelines and 4 quality improvement-related publications. ^aIncludes community-based prevalence and incidence studies on stroke in Africa. ^bIncludes hospital-based studies, whether of observational or interventional, retrospective or prospective, longitudinal or case–control designs. ^cRefers to studies that report the testing of a drug, procedure or other medical treatment in animals, where the disease of interest in the study was a stroke. ^dIncludes narrative reviews, scoping reviews, systematic reviews and meta-analyses.

Fig. 5. The stroke quadrangle.

The four pillars of the stroke quadrangle are surveillance, prevention, acute care and rehabilitation. Together, these pillars can lead to the reduction of stroke incidence, prevalence, disability and mortality. DALYs, disability-adjusted life years.

Fig. 6. Conceptual framework of the African Stroke Organization.

The aim of the African Stroke Organization (ASO) is to reduce the burden of stroke in Africa. This figure illustrates the framework through which the ASO plans to meet this goal. The colourful network represents the rich genetic, cultural and geographical diversity in Africa, and the neuronal network of the brain. The interconnected individuals represent the African Ubuntu Philosophy of inclusiveness, cooperation and collaboration. The pale green layer depicts the four core pillars of ASO activities: research; capacity-building programmes; development of stroke services; promotion of stroke awareness, and advocacy and empowerment of survivors of stroke, their families and their caregivers. The dark green layer represents the broader core values of the ASO: working with partners to involve people and positively influence practice and policy. Adapted with permission from ref., SAGE.