Risk Factor Characterization of Ischemic Stroke Subtypes Among West Africans

Epigenetics as a target to mitigate excess stroke risk in people of African ancestry: A scoping review

BACKGROUND

Globally, individuals of African ancestry have a relatively greater stroke preponderance compared to other racial/ethnic groups. The higher prevalence of traditional stroke risk factors in this population, however, only partially explains this longstanding disparity. Epigenetic signatures are transgenerational and could be a plausible therapeutic target to further bend the stroke disparities curve for people of African ancestry. There is, however, limited data on epigenetics and stroke risk in this population.

PURPOSE

To examine existing evidence and knowledge gaps on the potential contribution of epigenetics to excess stroke risk in people of African ancestry and avenues for mitigation.

MATERIALS AND METHODS

We conducted a scoping review of studies published between January 2003 and July 2023, on epigenetics and stroke risk. We then summarized our findings, highlighting the results for people of African ancestry.

RESULTS

Of 104 studies, there were only 6 studies that specifically looked at epigenetic mechanisms and stroke risk in people of African ancestry. Results of these studies show how patterns of DNA methylation and non-coding RNA interact with lifestyle choices, xenobiotics, and FVIII levels to raise stroke risk in people of African ancestry. However, no studies evaluated epigenetic patterns as actionable targets for the influence of psychosocial stressors or social context and excess stroke risk in this population (versus others). Also, no studies interrogated the role of established or novel therapeutic agents with the potential to reprogram DNA by adding or removing epigenetic markers in people of African ancestry.

CONCLUSION

Epigenetics potentially offers a promising target for modifying the effects of lifestyle, environmental exposures, and other factors that differentially affect people of African ancestry and place them at relatively greater stroke risk compared to other populations. Studies that precisely assess the pathways by which epigenetic mechanisms modulate population-specific disparities in the risk of stroke are needed.

A systematic review of the epidemiology and the public health implications of stroke in Sub-Saharan Africa

BACKGROUND

With approximately 11 million strokes occurring annually worldwide, and over 6.5 million deaths annually, stroke has made its place as one of the major killers in the world. Although developing countries make up more than 4/5 of the global stroke burden, well-grounded information on stroke epidemiology remains lacking there.

AIMS

This systematic review study aimed to provide a synthesis of studies on the incidence and prevalence of stroke among adults in sub-Saharan Africa (SSA), subsequently deduce the associated risk factors and public health implications (mortality rates and economic costs) of the disease on the population of this region.

METHODS

A systematic review of studies carried out in the region and published on PUBMED. Eligibility criteria were established using the PEO (Population/Patient, Exposure, Outcome) format. Research articles investigating either (or all) of the following: ischemic or haemorrhagic stroke, incidence, prevalence, and risk factors of stroke in adults (≥ 18 years old), in at least one region of SSA were included. Exclusion criteria comprised studies involving populations younger than 18 years old, research conducted outside the designated research region, and articles inaccessible in full text. The PRISMA guidelines were used for the search strategy.

RESULTS

Fifty-two studies were included review. Among them, over 11 studies investigated the prevalence of the disease. Some older studies within the continent (Nigeria, 2011) showed a prevalence of 1.3 per 100 while more recent studies (Zambia, 2021) showed a prevalence of 4.3 per 1000. The highest prevalence noted in this region was in Madagascar (2017) with 48.17 per 100, while the lowest was recorded in (Zimbabwe, 2017) with 0.61 per 100. The study in Tanzania showed a crude incidence of 94·5 per 100 000 (76·0-115·0) while the study in Ghana in 2018 showed an incidence of 14.19 events per 1000 person-years [10.77-18.38]. The identified risk factors included hypertension, diabetes, smoking, alcohol consumption, physical inactivity, poor diets (more salt, less vegetables), dyslipidaemia, HIV/AIDS co-infection, heart disease (cardiomyopathies, cardiac arrhythmias), obesity, previous stroke and/or family history of stroke. Over 21 studies investigated the mortality rates due to stroke in SSA, with most of the studies being in West Africa. These studies revealed mortality rates as high as 43.3% in Ghana, and as low as 10.9% in Cameroon. Few studies reported on the economic costs of stroke in the region; two in Benin, two in Nigeria and one in Tanzania.

CONCLUSION

The increasing incidence/prevalence, lifestyle factors and interactions with other diseases, including major communicable diseases, stroke is becoming a pressing public health problem for SSA. Reducing the incidence of stroke in Africa will surely lower mortality, morbidity, disability, and the neurological as well as cognitive aftereffects of stroke, as is clear from the experience of higher-income nations. We recommend a collective intervention involving the governments of nations, international organizations, civil society, and the private sector for greater impact and sustainable outcomes reducing the epidemiology and implications of stroke in SSA.

Stroke occurrence by hypertension treatment status in Ghana and Nigeria: A case-control study

BACKGROUND

Hypertension is preeminent among the vascular risk factors for stroke occurrence. The wide gaps in awareness, detection, treatment, and control rates of hypertension are fueling an epidemic of stroke in sub-Saharan Africa.

PURPOSE

To quantify the contribution of untreated, treated but uncontrolled, and controlled hypertension to stroke occurrence in Ghana and Nigeria.

METHODS

The Stroke Investigative Research and Educational Network (SIREN) is a case-control study across 16 study sites in Ghana and Nigeria. Cases were acute stroke (n = 3684) with age- and sex-matched stroke-free controls (n = 3684). We evaluated the associations of untreated hypertension, treated but uncontrolled hypertension, and controlled hypertension at BP of <140/90 mmHg with risk of stroke occurrence. We assessed the adjusted odds ratio and population-attributable risk of hypertension treatment control status associated with stroke occurrence.

RESULTS

The frequencies of no hypertension, untreated hypertension, treated but uncontrolled hypertension and controlled hypertension among stroke cases were 4.0%, 47.7%, 37.1%, and 9.2% vs 40.7%, 34.9%, 15.9%, and 7.7% respectively among stroke-free controls, p < 0.0001. The aOR and PAR (95% CI) for untreated hypertension were 6.58 (5.15-8.41) and 35.4% (33.4-37.4); treated but uncontrolled hypertension was 9.95 (7.60-13.02) and 35.9% (34.2-37.5); and controlled hypertension 5.37 (3.90-7.41) and 8.5% (7.6-9.5) respectively. Untreated hypertension contributed a PAR of 47.5% to the occurrence of intracerebral hemorrhage vs 29.5% for ischemic stroke. The aOR of untreated hypertension for stroke occurrence was 13.31 (7.64-23.19) for <50 years; 7.14 (4.51-11.31) for 50-64 years; and 3.48 (2.28-5.30) for 65 years or more.

CONCLUSION

The contribution of untreated hypertension and treated but uncontrolled hypertension to stroke occurrence among indigenous Africans is substantial. Implementing targeted interventions that address gaps in hypertension prevention and treatment, involving the local population, healthcare providers, and policymakers, can potentially substantially reduce the escalating burden of strokes in Africa.

Behavioural and nutritional risk factors for cardiovascular diseases among the Ghanaian population- a cross-sectional study

BACKGROUND

Lifestyle behavioural risk factors have been linked to increased cardiovascular disease. Recent data have shown increased atherosclerotic cardiovascular disease (ASCVD) burden in Ghana. This study aimed to describe the behavioural and nutritional risk factors for ASCVD among Ghanaians, and how these risk factors vary by ethnicity, demography and residence.

METHODS

We used data from the Ghana Heart Study, a community-based cross-sectional study that recruited participants from eight communities from four regions using a multi-stage sampling technique. Information about various lifestyle behaviours (LBs), including cigarette smoking, alcohol intake, physical inactivity, and fruit and vegetable intake, was obtained using a questionnaire. Data was analysed using IBM SPSS statistics 25. Univariate and multivariate analysis was used to test associations between demographic characteristics and various LBs.

RESULTS

The participants' median (interquartile) age was 46.0 (27.0) years. Of the 1,106 participants (58% females, 80.4% urban dwellers), 8.6% reported using tobacco, 48.9% alcohol, 83.7% physically inactive, 81.4% and 84.9% inadequate fruit and vegetable intake, respectively. Age, sex, ethnicity, and religion were associated with tobacco use, whereas age, sex, educational level, marital status, ethnicity, employment status, and region of residence were associated with physical inactivity. Similarly, ethnicity, employment status, and residence region were associated with inadequate fruit and vegetable intake. Rural dwellers were more likely to be physically inactive and consume inadequate fruits and vegetables. Almost 92% had a combination of two or more LBs. The main predictors of two or more LBs for ASCVD were educational level, marital status, ethnicity, and employment status.

CONCLUSION

Lifestyle risk factors for ASCVD were highly prevalent in Ghana, with significant age, sex, ethnic, and regional differences. These risky lifestyle behaviors tend to occur together and must be considered in tailoring public health education.

TRIAL REGISTRATION

The study was registered at http://www.chictr.org.cn as ChiCTR1800017374.

A potential relationship between MMP-9 rs2250889 and ischemic stroke susceptibility

Purpose

Ischemic stroke (IS), a serious cerebrovascular disease, greatly affects people's health and life. Genetic factors are indispensable for the occurrence of IS. As a biomarker for IS, the MMP-9 gene is widely involved in the pathophysiological process of IS. This study attempts to find out the relationship between MMP-9 polymorphisms and IS susceptibility.

Methods

A total of 700 IS patients and 700 healthy controls were recruited. The single nucleotide polymorphism (SNP) markers of the MMP-9 gene were genotyped by the MassARRAY analyzer. Multifactor dimensionality reduction (MDR) was applied to generate SNP-SNP interaction. Furthermore, the relationship between genetic variations (allele and genotype) of the MMP-9 gene and IS susceptibility was analyzed by calculating odds ratios (ORs) and 95% confidence intervals (CIs).

Results

Our results demonstrated that rs2250889 could significantly increase the susceptibility to IS in the codominant, dominant, overdominant, and log-additive models (p < 0.05). Further stratification analysis showed that compared with the control group, rs2250889 was associated with IS risk in different case groups (age, female, smoking, and non-drinking) (p < 0.05). Based on MDR analysis, rs2250889 was the best model for predicting IS risk (cross-validation consistency: 10/10, OR = 1.56 (1.26-1.94), p < 0.001).

Conclusion

Our study preliminarily confirmed that SNP rs2250889 was significantly associated with susceptibility to IS.

Participation by patients from low- and middle-income countries (LMICs) in trial evidence supporting secondary stroke prevention guideline recommendations

BACKGROUND

One out of every four strokes is a highly preventable recurrent stroke. However, while low-and-middle-income countries (LMICs) experience a disproportionate global burden of stroke, individuals in these regions seldomly participate in pivotal clinical trials, which form the basis for international expert consensus guideline recommendations.

OBJECTIVE

To evaluate a contemporary and globally prominent expert consensus secondary stroke prevention guideline statement for the participation of clinical trial subjects recruited from LMICs in formulating key therapeutic recommendations.

METHODS

We examined the 2021 American Heart Association/American Stroke Association Guideline for the Prevention of Stroke in Patients with Stroke and TIA. All randomized controlled trials (RCTs) cited in the Guideline were independently reviewed by two authors for study populations and participating countries with a focus on trials for vascular risk factor control and management by underlying stroke mechanism. We also reviewed all cited systematic reviews and meta-analyses for the original RCTs.

RESULTS

Among 320 secondary stroke prevention clinical trials, 262 (82%) focused on vascular risk control addressing diabetes (n = 26), hypertension (n = 23), obstructive sleep apnea (n = 13), dyslipidaemia (n = 10), lifestyle (n = 188) and obesity (n = 2); and 58 focused on stroke mechanism management including atrial fibrillation (n = 10), large vessel atherosclerosis (n = 45) and small vessel disease (n = 3). Overall, 53 of 320 studies (16.6%) had contributions from LMICs ranging from 55.6% for dyslipidemia, 40.7% for diabetes, 26.1% for hypertension, 15.4% for OSA, 6.4% for lifestyle, 0% for obesity, and by mechanism: 60.0% for atrial fibrillation, 22.2% large vessel atherosclerosis and 33.3% for small vessel disease trials. Only 19 (5.9%) of the trials had participatory contributions from a country in sub-Saharan Africa (South Africa only).

CONCLUSIONS

Compared to their global burden of stroke, LMICs are underrepresented in key clinical trials used in formulating a prominent global stroke prevention guideline. While current therapeutic recommendations are likely applicable to practice settings throughout the world, greater involvement of patients from LMIC settings will enhance the contextual relevance and generalizability of recommendations to these disparate populations.

Differential associations between pre-diabetes, diabetes and stroke occurrence among West Africans

BACKGROUND

There are limited data from Africa on the burden and associations between pre-diabetes (pre-DM), diabetes mellitus (DM) and stroke occurrence in a region experiencing a profound rise in stroke burden.

PURPOSE

To characterize the associations between stroke and dysglycemic status among West Africans.

METHODS

The Stroke Investigative Research and Educational Network (SIREN) is a multicenter, case-control study involving 15 sites in Ghana and Nigeria. Cases include adults aged ≥18 years with clinical and radiological evidence of an acute stroke. Controls were age-and-gender matched stroke-free adults. Detailed evaluations for vascular factors were performed. Pre-diabetes was defined as HBA1c of 5.7%-6.4% or Fasting blood glucose (FBG) 5.6-7.0 mmol/L and DM as HBA1c >6.5% or FBG>7.0 mmol/L. We used conditional logistic regression to estimate adjusted odds ratios (aOR) with 95% Confidence Interval.

RESULTS

Among 2,935 stroke cases the mean age was 60.0 ± 14.2 years with 55.2% being males. By glycemic status, 931 (31.7%) were euglycemic, 633 (21.6%) had Pre-diabetes and 1371 (46.7%) had DM. Of the age- and sex-matched stroke-free controls 69.2% were euglycemic, 13.3% had pre-DM and 17.5% had DM. Pre-DM [aOR (95% CI): 3.68(2.61-5.21)] and DM [4.29 (3.19-5.74)] were independently associated with stroke. The aOR of Pre-DM for ischemic stroke 3.06 (2.01-4.64)] was lower than 4.82 (3.37-6.89) for DM. However, the aOR of Pre-DM for hemorrhagic stroke 6.81 (95% CI: 3.29 - 14.08)] was higher than 3.36 (1.94-5.86) for DM. Furthermore, the aOR of pre-DM for ischemic stroke subtypes were 9.64 (1.30-71.57) for cardio-embolic stroke, 3.64 (1.80-7.34) for small-vessel occlusive disease and 4.63 (0.80-26.65) for large-vessel disease.

CONCLUSION

Pre-DM is strongly and independently associated with stroke in Africans. Improving glycemic control through screening, healthy lifestyle and pharmacotherapy at a population level may be strategic in reducing the rising burden of stroke in Africa.

Long-term determinants of death after stroke in Ghana: Analysis by stroke types & subtypes

BACKGROUND

Determinants of long-term mortality after stroke by mechanistic type and subtype are unknown in sub-Saharan Africa (SSA). Such data are crucial for targeting specific pathophysiologic pathways to improve stroke outcomes in the region.

PURPOSE

To evaluate rates and predictors of mortality up to 8 years after stroke, by type and subtype, in Ghana.

METHODS

We prospectively collected data on stroke patients presenting at a tertiary medical facility in Ghana between 2013 and 2018 who were followed up until October 31, 2021. Stroke diagnosis was confirmed using a Computerized Tomography scan; ischemic strokes were mechanistically typed using the TOAST classification while intracerebral hemorrhages were subtyped using the SMASH-U scheme. Demographic and clinical predictors of stroke mortality were evaluated using Cox proportional hazards regression modelling.

RESULTS

Of 564 patients encountered during the study period, data on vital status were available for 556 (98.6%) subjects at discharge and 442 (78.4%) on follow-up. Mean age was 61.1 ±15.1 years, and 223 (53.1%) were male. Mortality rates at 1, 3, 12, 36, 60 and 96 months were 37.5%, 43.2%, 49.7%, 57.4%, 62.9%, and 73.7% respectively. Three (3) factors remained significantly associated with risk of death namely age, adjusted hazard ratios (aHR) of 1.12 (95%CI: 1.04-1.20), no formal education 1.36 (95% CI: 1.02-1.81) and modified Rankin score 1.67 (95%CI: 1.42 - 1.98) for each unit rise. For ischemic stroke the four (4) factors associated with long-term mortality were low formal education, low monthly income, having diabetes mellitus and higher functional score on admission. For intracerebral hemorrhage, the two factors were increasing age and high functional score.

CONCLUSION

Stroke severity is the key predictor of long-term mortality after an index stroke in Ghana, regardless of the underlying pathophysiologic mechanism. Instituting acute stroke systems of care to facilitate timely reperfusion efforts may greatly improve long term survival outcomes after stroke in SSA.

TNF-α (G-308A) Polymorphism, Circulating Levels of TNF-α and IGF-1: Risk Factors for Ischemic Stroke—An Updated Meta-Analysis

Objective

Accumulated studies have explored gene polymorphisms and circulating levels of tumor necrosis factor (TNF)-α and insulin-like growth factor (IGF)-1 in the etiology of ischemic stroke (IS). Of the numerous etiopathological factors for IS, a single-nucleotide polymorphism (SNP) rs1800629 located in the TNF-α gene promoter region and increased levels of TNF-α were found to be associated with IS in different ethnic backgrounds. However, the published results are inconsistent and inconclusive. The primary objective of this meta-analysis was to investigate the concordance between rs1800629 polymorphism and IS. A secondary aim was to explore circulating levels of TNF-α and IGF-1 with IS in different ethnic backgrounds and different sourced specimens.

Methods

In this study, we examined whether rs1800629 genetic variant and levels of TNF-α and IGF-1 were related to the etiology of IS by performing a meta-analysis. Relevant case-control studies were retrieved by database searching and systematically selected according to established inclusion criteria.

Results

A total of 47 articles were identified that explored the relationship between the rs1800629 polymorphism and levels of TNF-α and IGF-1 with IS risk susceptibility. Statistical analyses revealed a significant association between the rs1800629 polymorphism and levels of TNF-α and IGF-1 with IS pathogenesis.

Conclusion

Our findings demonstrated that the TNF-α rs1800629 polymorphism, the increased levels of TNF-α, and decreased levels of IGF-1 were involved in the etiology of IS.