Onoja Akpa

BACKGROUND: Sub-Saharan Africa has the highest incidence, prevalence, and fatality from stroke globally. Yet, only little information about context-specific risk factors for prioritising interventions to reduce the stroke burden in sub-Saharan Africa is available. We aimed to identify and characterise the effect of the top modifiable risk factors for stroke in sub-Saharan Africa. METHODS: The Stroke Investigative Research and Educational Network (SIREN) study is a multicentre, case-control study done at 15 sites in Nigeria and Ghana. Cases were adults (aged ≥18 years) with stroke confirmed by CT or MRI. Controls were age-matched and gender-matched stroke-free adults (aged ≥18 years) recruited from the communities in catchment areas of cases. Comprehensive assessment for vascular, lifestyle, and psychosocial factors was done using standard instruments. We used conditional logistic regression to estimate odds ratios (ORs) and population-attributable risks (PARs) with 95% CIs. FINDINGS: Between Aug 28, 2014, and June 15, 2017, we enrolled 2118 case-control pairs (1192 [56%] men) with mean ages of 59·0 years (SD 13·8) for cases and 57·8 years (13·7) for controls. 1430 (68%) had ischaemic stoke, 682 (32%) had haemorrhagic stroke, and six (<1%) had discrete ischaemic and haemorrhagic lesions. 98·2% (95% CI 97·2-99·0) of adjusted PAR of stroke was associated with 11 potentially modifiable risk factors with ORs and PARs in descending order of PAR of 19·36 (95% CI 12·11-30·93) and 90·8% (95% CI 87·9-93·7) for hypertension, 1·85 (1·44-2·38) and 35·8% (25·3-46·2) for dyslipidaemia, 1·59 (1·19-2·13) and 31·1% (13·3-48·9) for regular meat consumption, 1·48 (1·13-1·94) and 26·5% (12·9-40·2) for elevated waist-to-hip ratio, 2·58 (1·98-3·37) and 22·1% (17·8-26·4) for diabetes, 2·43 (1·81-3·26) and 18·2% (14·1-22·3) for low green leafy vegetable consumption, 1·89 (1·40-2·54) and 11·6% (6·6-16·7) for stress, 2·14 (1·34-3·43) and 5·3% (3·3-7·3) for added salt at the table, 1·65 (1·09-2·49) and 4·3% (0·6-7·9) for cardiac disease, 2·13 (1·12-4·05) and 2·4% (0·7-4·1) for physical inactivity, and 4·42 (1·75-11·16) and 2·3% (1·5-3·1) for current cigarette smoking. Ten of these factors were associated with ischaemic stroke and six with haemorrhagic stroke occurrence. INTERPRETATION: Implementation of interventions targeting these leading risk factors at the population level should substantially curtail the burden of stroke among Africans. FUNDING: National Institutes of Health.

BACKGROUND AND PURPOSE: Stroke in lower and middle-income countries affects a young and productive age group. Data on factors associated with stroke in the young are sorely lacking from lower and middle-income countries. Our objective is to characterize the nature of stroke and its risk factors among young West Africans aged <50 years old. METHODS: The SIREN (Stroke Investigative Research and Educational Network) is a multicenter, case-control study involving 15 sites in Nigeria and Ghana. Cases included adults aged ≥18 years with computed tomography/magnetic resonance imaging-confirmed stroke. Controls were age-and gender-matched stroke-free adults recruited from the communities in catchment areas of cases. Comprehensive evaluation for vascular, lifestyle, and psychosocial factors was performed. We used conditional logistic regression to estimate odds ratios and population attributable risks with 95% confidence intervals. RESULTS: Five hundred fifteen (24.3%) out of 2118 cases enrolled were <50 years old. Among subjects <50 years old, hemorrhagic stroke proportion was 270 (52.5%) versus 245 (47.5%) for ischemic strokes. Etiologic subtypes of ischemic strokes included large artery atherosclerosis (40.0%), small vessel disease (28.6%), cardioembolism (11.0%), and undetermined (20.4%). Hypertension (91.7%), structural lesions (3.4%), and others (4.9%) were causally associated with hemorrhagic stroke. Six topmost modifiable factors associated with stroke in descending order of population attributable risk (95% confidence interval) were hypertension: 88.7% (82.5%-94.8%), dyslipidemia: 48.2% (30.6%-65.9%), diabetes mellitus: 22.6% (18.7%-26.5%), low green vegetable consumption: 18.2% (-6.8%-43.2%), stress: 14.5% (4.9%-24.1%), and cardiac disease: 8.4% (5.8%-11.1%). CONCLUSIONS: The high and rising burden of stroke among young Africans should be curtailed via aggressive, population-wide vascular risk factor control.

BACKGROUND: As the second leading cause of death and the leading cause of adult-onset disability, stroke is a major public health concern particularly pertinent in Sub-Saharan Africa (SSA), where nearly 80% of all global stroke mortalities occur, and stroke burden is projected to increase in the coming decades. However, traditional and emerging risk factors for stroke in SSA have not been well characterized, thus limiting efforts at curbing its devastating toll. The Stroke Investigative Research and Education Network (SIREN) project is aimed at comprehensively evaluating the key environmental and genomic risk factors for stroke (and its subtypes) in SSA while simultaneously building capacities in phenomics, biobanking, genomics, biostatistics, and bioinformatics for brain research. METHODS: SIREN is a transnational, multicentre, hospital and community-based study involving 3,000 cases and 3,000 controls recruited from 8 sites in Ghana and Nigeria. Cases will be hospital-based patients with first stroke within 10 days of onset in whom neurovascular imaging will be performed. Etiological and topographical stroke subtypes will be documented for all cases. Controls will be hospital- and community-based participants, matched to cases on the basis of gender, ethnicity, and age (±5 years). Information will be collected on known and proposed emerging risk factors for stroke. STUDY SIGNIFICANCE: SIREN is the largest study of stroke in Africa to date. It is anticipated that it will shed light on the phenotypic characteristics and risk factors of stroke and ultimately provide evidence base for strategic interventions to curtail the burgeoning burden of stroke on the sub-continent.

Hypertension and obesity are the most important modifiable risk factors for cardiovascular diseases, but their association is not well characterized in Africa. We investigated regional patterns and association of obesity with hypertension among 30 044 continental Africans. We harmonized data on hypertension (defined as previous diagnosis/use of antihypertensive drugs or blood pressure [BP]≥140/90 mmHg/BP≥130/80 mmHg) and obesity from 30 044 individuals in the Cardiovascular H3Africa Innovation Resource across 13 African countries. We analyzed data from population-based controls and the Entire Harmonized Dataset. Age-adjusted and crude proportions of hypertension were compared regionally, across sex, and between hypertension definitions. Logit generalized estimating equation was used to determine the independent association of obesity with hypertension ( P value &lt;5%). Participants were 56% women; with mean age 48.5±12.0 years. Crude proportions of hypertension (at BP≥140/90 mmHg) were 47.9% (95% CI, 47.4–48.5) for Entire Harmonized Dataset and 42.0% (41.1–42.7) for population-based controls and were significantly higher for the 130/80 mm Hg threshold at 59.3% (58.7–59.9) in population-based controls. The age-adjusted proportion of hypertension at BP≥140/90 mmHg was the highest among men (33.8% [32.1–35.6]), in western Africa (34.7% [33.3–36.2]), and in obese individuals (43.6%; 40.3–47.2). Obesity was independently associated with hypertension in population-based controls (adjusted odds ratio, 2.5 [2.3–2.7]) and odds of hypertension in obesity increased with increasing age from 2.0 (1.7–2.3) in younger age to 8.8 (7.4–10.3) in older age. Hypertension is common across multiple countries in Africa with 11.9% to 51.7% having BP≥140/90 mmHg and 39.5% to 69.4% with BP≥130/80 mmHg. Obese Africans were more than twice as likely to be hypertensive and the odds increased with increasing age.