International Migration and Cardiovascular Health: Unraveling the Disease Burden Among Migrants to North America and Europe

Europe and North America are the 2 largest recipients of international migrants from low-resource regions in the world. Here, large differences in cardiovascular disease (CVD) morbidity and death exist between migrants and the host populations. This review discusses the CVD burden and its most important contributors among the largest migrant groups in Europe and North America as well as the consequences of migration to high-income countries on CVD diagnosis and therapy. The available evidence indicates that migrants in Europe and North America generally have a higher CVD risk compared with the host populations. Cardiometabolic, behavioral, and psychosocial factors are important contributors to their increased CVD risk. However, despite these common denominators, there are important ethnic differences in the propensity to develop CVD that relate to pre- and postmigration factors, such as socioeconomic status, cultural factors, lifestyle, psychosocial stress, access to health care and health care usage. Some of these pre- and postmigration environmental factors may interact with genetic (epigenetics) and microbial factors, which further influence their CVD risk. The limited number of prospective cohorts and clinical trials in migrant populations remains an important culprit for better understanding pathophysiological mechanism driving health differences and for developing ethnic-specific CVD risk prediction and care. Only by improved understanding of the complex interaction among human biology, migration-related factors, and sociocultural determinants of health influencing CVD risk will we be able to mitigate these differences and truly make inclusive personalized treatment possible.

Serum Adiponectin and Leptin Among Ghanaian Migrants in Amsterdam and Their Compatriots in Rural and Urban Ghana: The RODAM Study

Background

The rapidly rising cardiometabolic disease (CMD) burden in urbanizing sub-Saharan African populations and among sub-Saharan African migrants in Europe likely affects serum adiponectin and leptin levels, but this has not yet been quantified.

Objectives

To compare the serum levels of adiponectin and leptin among migrant, and non-migrant (urban and rural) populations of Ghanaian descent.

Methods

Cross-sectional analysis of serum leptin and adiponectin in the multi-centre Research on Obesity and Diabetes among African Migrants (RODAM) study. Logistic-regression models were used to examine the association between these adipocyte-derived hormones after stratification (sex, geographic area) and adjustments for potential confounders.

Results

A total of 2518 Ghanaians were included. Rural participants had the highest serum adiponectin and lowest leptin levels compared to Amsterdam and urban Ghanaians (P < .001). In fully adjusted models, participants living in urban Ghana had significantly higher odds of hyperleptinemia compared to rural participants (women-odds ratio 2.88; 95% CI, 1.12-7.38, P = .028 and men 43.52, 95% CI, 4.84-391.25, P < .001). Urban Ghanaian men also had higher odds of elevated leptin: adiponectin ratio (6.29, 95% CI, 1.43-27.62, P = .015). The odds of hyperleptinemia were only higher in Amsterdam Ghanaian men (10.56; 95% CI, 1.11-100.85, P = .041), but not in women (0.85; 95% CI, 0.30-2.41, P = .759). There was no significant association between hypoadiponectinemia and geographical location in both sexes.

Conclusion

Urbanization is associated with serum adiponectin and leptin levels after adjusting for confounding covariates in sub-Saharan Africans. These findings serve as a backdrop for further research on the role adipokines play in CMD epidemiology among Africans.

Assessing the Effectiveness of mHealth Interventions for Diabetes and Hypertension Management in Africa: Systematic Review and Meta-Analysis

Background

Mobile health (mHealth) interventions are effective in improving chronic disease management, mainly in high-income countries. However, less is known about the efficacy of mHealth interventions for the reduction of cardiovascular risk factors, including for hypertension and diabetes, which are rapidly increasing in low- and middle-income countries.

Objective

This study aimed to assess the efficacy of mHealth interventions for diabetes and hypertension management in Africa.

Methods

We searched PubMed, Cochrane Library, Google Scholar, African Journals Online, and Web of Science for relevant studies published from inception to July 2022. The main outcomes of interest were changes in hemoglobin A1c (HbA1c), systolic blood pressure, and diastolic blood pressure. The random or fixed effect model was used for the meta-analysis, and the I2 statistic was used to gauge study heterogeneity. Z tests and P values were used to evaluate the effect of mHealth interventions on HbA1c and blood pressure levels.

Results

This review included 7 studies (randomized controlled trials) with a total of 2249 participants. Two studies assessed the effect of mHealth on glycemic control, and 5 studies assessed the effect of mHealth on blood pressure control. The use of mHealth interventions was not associated with significant reductions in HbA1c levels (weighted mean difference [WMD] 0.20, 95% CI -0.40 to 0.80; P=.51) among patients with diabetes and systolic blood pressure (WMD -1.39, 95% CI -4.46 to 1.68; P=.37) and diastolic blood pressure (WMD 0.36, 95% CI -1.37 to 2.05; P=.69) among patients with hypertension. After conducting sensitivity analyses using the leave-one-out method, the Kingue et al study had an impact on the intervention, resulting in a 2 mm Hg reduction in systolic blood pressure (WMD -2.22, 95% CI -3.94 to -0.60; P=.01) but was nonsignificant for diastolic blood pressure and HbA1c levels after omitting the study.

Conclusions

Our review provided no conclusive evidence for the effectiveness of mHealth interventions in reducing blood pressure and glycemic control in Africa among persons with diabetes and hypertension. To confirm these findings, larger randomized controlled trials are required.

Epigenome-wide association study of plasma lipids in West Africans: the RODAM study

BACKGROUND

DNA-methylation has been associated with plasma lipid concentration in populations of diverse ethnic backgrounds, but epigenome-wide association studies (EWAS) in West-Africans are lacking. The aim of this study was to identify DNA-methylation loci associated with plasma lipids in Ghanaians.

METHODS

We conducted an EWAS using Illumina 450k DNA-methylation array profiles of extracted DNA from 663 Ghanaian participants. Differentially methylated positions (DMPs) were examined for association with plasma total cholesterol (TC), LDL-cholesterol, HDL-cholesterol, and triglycerides concentrations using linear regression models adjusted for age, sex, body mass index, diabetes mellitus, and technical covariates. Findings were replicated in independent cohorts of different ethnicities.

FINDINGS

We identified one significantly associated DMP with triglycerides (cg19693031 annotated to TXNIP, regression coefficient beta -0.26, false discovery rate adjusted p-value 0.001), which replicated in-silico in South African Batswana, African American, and European populations. From the top five DMPs with the lowest nominal p-values, two additional DMPs for triglycerides (CPT1A, ABCG1), two DMPs for LDL-cholesterol (EPSTI1, cg13781819), and one for TC (TXNIP) replicated. With the exception of EPSTI1, these loci are involved in lipid transport/metabolism or are known GWAS-associated loci. The top 5 DMPs per lipid trait explained 9.5% in the variance of TC, 8.3% in LDL-cholesterol, 6.1% in HDL-cholesterol, and 11.0% in triglycerides.

INTERPRETATION

The top DMPs identified in this study are in loci that play a role in lipid metabolism across populations, including West-Africans. Future studies including larger sample size, longitudinal study design and translational research is needed to increase our understanding on the epigenetic regulation of lipid metabolism among West-African populations.

FUNDING

European Commission under the Framework Programme (grant number: 278901).

Cohort profile: Research on Obesity and Diabetes among African Migrants in Europe and Africa Prospective (RODAM-Pros) cohort study

PURPOSE

The Research on Obesity and Diabetes among African Migrants (RODAM) prospective (RODAM-Pros) cohort study was established to identify key changes in environmental exposures and epigenetic modifications driving the high burden of cardiovascular disease (CVD) risk among sub-Saharan African migrants.

PARTICIPANTS

All the participants in the RODAM cross-sectional study that completed the baseline assessment (n=5114) were eligible for the follow-up of which 2165 participants (n=638 from rural-Ghana, n=608 from urban-Ghana, and n=919 Ghanaian migrants in Amsterdam, the Netherlands) were included in the RODAM-Pros cohort study. Additionally, we included a subsample of European-Dutch (n=2098) to enable a comparison to be made between Ghanaian migrants living in the Netherlands and the European-Dutch host population.

FINDINGS TO DATE

Follow-up data have been collected on demographics, socioeconomic status, medical history, psychosocial environment, lifestyle factors, nutrition, anthropometrics, blood pressure, fasting blood, urine and stool samples. Biochemical analyses included glucose metabolism, lipid profile, electrolytes and renal function, liver metabolism and inflammation. In a subsample, we assessed DNA methylation patterns using Infinium 850K DNA Methylation BeadChip. Baseline results indicated that migrants have higher prevalence of CVD risk factors than non-migrants. Epigenome-wide association studies suggest important differences in DNA methylation between migrants and non-migrants. The follow-up study will shed further light on key-specific environmental exposures and epigenetic modifications contributing to the high burden of CVD risk among sub-Saharan African migrants.

FUTURE PLANS

Follow-up is planned at 5-year intervals, baseline completed in 2015 and first follow-up completed in 2021.

An explorative epigenome-wide association study of plasma renin and aldosterone concentration in a Ghanaian population: the RODAM study

BACKGROUND

The epigenetic regulation of the renin-angiotensin-aldosterone system (RAAS) potentially plays a role in the pathophysiology underlying the high burden of hypertension in sub-Saharan Africans (SSA). Here we report the first epigenome-wide association study (EWAS) of plasma renin and aldosterone concentrations and the aldosterone-to-renin ratio (ARR).

METHODS

Epigenome-wide DNA methylation was measured using the Illumina 450K array on whole blood samples of 68 Ghanaians. Differentially methylated positions (DMPs) were assessed for plasma renin concentration, aldosterone, and ARR using linear regression models adjusted for age, sex, body mass index, diabetes mellitus, hypertension, and technical covariates. Additionally, we extracted methylation loci previously associated with hypertension, kidney function, or that were annotated to RAAS-related genes and associated these with renin and aldosterone concentration.

RESULTS

We identified one DMP for renin, ten DMPs for aldosterone, and one DMP associated with ARR. Top DMPs were annotated to the PTPRN2, SKIL, and KCNT1 genes, which have been reported in relation to cardiometabolic risk factors, atherosclerosis, and sodium-potassium handling. Moreover, EWAS loci previously associated with hypertension, kidney function, or RAAS-related genes were also associated with renin, aldosterone, and ARR.

CONCLUSION

In this first EWAS on RAAS hormones, we identified DMPs associated with renin, aldosterone, and ARR in a SSA population. These findings are a first step in understanding the role of DNA methylation in regulation of the RAAS in general and in a SSA population specifically. Replication and translational studies are needed to establish the role of these DMPs in the hypertension burden in SSA populations.

C-reactive protein and hypertension among Ghanaian migrants and their homeland counterparts: the Research on Obesity and Diabetes among African Migrants study

BACKGROUND

Hypertension (HTN) is a growing public health problem in sub-Saharan Africa (SSA) and SSA migrants in Europe. Elevated levels of inflammatory marker C-reactive protein (CRP) have been linked to HTN but the relationship of CRP and HTN among SSA populations has not been studied. To address this knowledge gap, we studied the association between CRP and HTN in migrant and nonmigrant SSA populations residing in different settings.

METHODS

Cross-sectional data from the multicentre Research on Obesity and Diabetes among African Migrants (RODAM) study were analysed including 5683 Ghanaians aged at least 18 years, residing in rural and urban Ghana, and Europe. Multivariate logistic regression analyses were used to assess the association between high levels of CRP (≥3 mg/l) and HTN (SBP ≥140 mmHg and/or DBP ≥90 mmHg and/or use of antihypertensive medication) per geographical site and sex.

RESULTS

The association between CRP levels and HTN varied by sex and geographical location. In age-adjusted models, there was an association between high CRP levels and HTN in urban-Ghanaian women (odds ratio 1.50, 95% confidence interval 1.10-2.03), and European-Ghanaian men (1.68, 1.16-2.43) and women (1.63, 1.28-2.07). However, these associations were attenuated after adjustment for conventional risk factors, especially BMI. No association was found in rural-Ghanaians or urban-Ghanaian men.

CONCLUSION

Our findings show an association between CRP and HTN among Ghanaian migrants and urban-Ghanaian women, however, this was largely explained by conventional risk factors. Thus, prevention of conventional risk factors, in particular obesity, may help to reduce the potentially low-grade inflammatory mechanism underlying HTN.

Serum potassium concentration and its association with hypertension among Ghanaian migrants and non-migrants: The RODAM study

BACKGROUND AND AIMS

Low serum potassium concentration is associated with hypertension, but whether the same association can be found in African origin populations, is unknown. We assessed serum potassium concentration, and its association with hypertension among Ghanaians living in different geographical locations.

METHODS

Baseline data of 962 rural, 1420 urban, and 2947 migrant Ghanaians from the Research on Obesity and Diabetes among African Migrants study were analysed. Mean serum potassium concentration was compared between the groups, and the association between serum potassium and hypertension was assessed using multivariate regression analyses.

RESULTS

Mean serum potassium concentration was higher in rural Ghana (4.28, 95% confidence interval 4.25-4.32 mmol/L) than in Ghanaians living in Amsterdam (3.90, 3.88-3.92 mmol/L) and London (4.11, 4.07-4.14 mmol/L), but lower than in Ghanaians living in urban Ghana (4.38, 4.34-4.42 mmol/L) and Berlin (4.57, 4.51-4.62 mmol/L) in both sexes. In the age-adjusted analyses, serum potassium was associated with hypertension in urban- (odds ratio 0.44, 0.23-0.82), London- (0.34, 0.17-0.64) and Amsterdam-Ghanaian males (0.41, 0.20-0.86), and in rural- (0.49, 0.28-0.84), London- (0.29, 0.17-0.49) and Amsterdam-Ghanaian females (0.33, 0.17-0.64). However, after adjustment for demographic, lifestyle, and health factors, serum potassium was associated with hypertension in Amsterdam-Ghanaian males only (0.12, 0.02-0.59).

CONCLUSIONS

This study shows differences in mean serum potassium among Ghanaian populations living in different locations in Europe and Ghana, and different associations with hypertension between sites. Further research should focus on elucidating the mechanism underlying potassium handling and blood pressure regulation in African populations, in order to mitigate the burden of hypertension among these populations.

Type 2 diabetes burden among migrants in Europe: unravelling the causal pathways

European populations are ethnically and culturally diverse due to international migration. Evidence indicates large ethnic inequalities in the prevalence of type 2 diabetes. This review discusses the burden of type 2 diabetes and its related complications, and the potential explanatory mechanisms among migrants in Europe. The current available data suggest that the rate of type 2 diabetes is higher in all migrant groups and that they develop this disease at an earlier age than the host European populations. The level of diabetes awareness among migrant populations is high, but glycaemic control remains suboptimal compared with Europeans. The culturally adapted lifestyle modification intervention trials to prevent type 2 diabetes mainly focus on South Asian adults in Europe. Diabetes-related microvascular and macrovascular complications remain a major burden among migrant populations in Europe. Earlier studies found higher mortality rates among migrants, but recent studies seem to suggest a shifting trend in favour of first-generation migrants. However, the extent of the burden of type 2 diabetes varies across migrant groups and European countries. Despite the higher burden of type 2 diabetes among migrants, the key underlying factors are not well understood mainly due to limited investment in basic science research and development of prospective cohort studies. We hypothesise that the underlying risk factors for the high burden of type 2 diabetes and its related complications in migrants are multifaceted and include pre-migration factors, post-migration factors and genetic predispositions. Given the multi-ethnic nature of the current European population, there is a clear need for investment in research among migrant populations to gain insight into factors driving the high burden of type 2 diabetes and related complications to facilitate prevention and treatment efforts in Europe.

Determinants of suboptimal blood pressure control in a multi-ethnic population: The Healthy Life in an Urban Setting (HELIUS) study

Among ethnic minority groups in Europe, blood pressure (BP) control is often suboptimal. We aimed to identify determinants of suboptimal BP control in a multi‐ethnic population. We analyzed cross‐sectional data of the Healthy Life in an Urban Setting (HELIUS) study, including 3571 participants aged 18‐70 with prescribed antihypertensive medication, of various ethnic backgrounds (500 Dutch, 1052 African Surinamese, 656 South‐Asian Surinamese, 637 Ghanaian, 433 Turkish, and 293 Moroccan) living in Amsterdam, the Netherlands. 53.3% of the population had suboptimal BP control, defined as BP ≥140/90 mmHg despite prescribed antihypertensives. Using multivariate logistic regression analysis, female sex (OR 0.50, 95%CI 0.43‐0.59), being married (0.83, 0.72‐0.96), smoking (0.78, 0.65‐0.94), alcohol intake (0.80, 0.66‐0.96), obesity (1.67, 1.35‐2.06), cardiovascular disease (CVD) history (0.56, 0.46‐0.68), non‐adherence to antihypertensives (1.26, 1.00‐1.58), and family history of hypertension (1.19, 1.02‐1.38) were identified to be independently associated with suboptimal BP control in the total population. In the ethnic‐stratified analysis, factors associated with better BP control were female sex (all ethnic groups), smoking (Turks), and CVD history (Dutch, South‐Asian Surinamese, and African Surinamese), whereas factors associated with suboptimal BP control were older age (Turks), obesity (Dutch, African Surinamese, Ghanaian, and Turks), and non‐adherence to antihypertensives (Dutch). In conclusion, our analysis identifies several key determinants that are independently associated with suboptimal BP control in a multi‐ethnic population, with some important variations between ethnic groups. Targeting these determinants may help to improve BP control.

Hypertension awareness, treatment and control among ethnic minority populations in Europe: a systematic review and meta-analysis

OBJECTIVE

Ethnic minority populations (EMPs) are disproportionally affected by hypertension-mediated complications compared with European host populations (EHPs), which might be due to disparities in hypertension awareness, treatment and control. We conducted a systematic review and meta-analysis to compare awareness, treatment and control rates among EMPs with EHPs.

METHODS

MEDLINE, EMBASE and Web of Science were searched from inception to 29 January 2020. Critical appraisal was performed according to methods of Hoy et al. Pooled odds ratios with corresponding 95% confidence intervals were calculated for these rates, stratified by ethnic group, using either random or fixed effect meta-analysis based on I2-statistics. Study was registered in PROSPRO (CRD42020107897).

RESULTS

A total of 3532 records were screened of which 16 were included in the analysis with data on 26 800 EMP and 57 000 EHP individuals. Compared with EHPs, African origin populations were more likely to be aware (odds ratio 1.26, 95% confidence interval 1.02-1.56) and treated (1.49, 1.18-1.88) for hypertension, but were less likely to have their blood pressure controlled (0.56, 0.40-0.78), whereas South Asian populations were more likely to be aware (1.15, 1.02-1.30), but had similar treatment and control rates. In Moroccan populations, hypertension awareness (0.79, 0.62-1.00) and treatment levels (0.77, 0.60-0.97) were lower compared with EHPs, while in Turkish populations awareness was lower (0.81, 0.65-1.00).

CONCLUSION

Levels of hypertension awareness, treatment and control differ between EMPs and EHPs. Effort should be made to improve these suboptimal rates in EMPs, aiming to reduce ethnic inequalities in hypertension-mediated complications.

The prevalence of metabolic syndrome among Ghanaian migrants and their homeland counterparts: the Research on Obesity and type 2 Diabetes among African Migrants (RODAM) study

Background

Metabolic syndrome (MetSyn) is an important risk factor for cardiovascular diseases and type 2 diabetes. It is unknown whether the MetSyn prevalence differs within a homogenous population residing in different settings in Africa and Europe. We therefore assessed the prevalence of MetSyn among Ghanaians living in rural- and urban-Ghana and Ghanaian migrants living in Europe.

Methods

We used data from the cross-sectional multi-centre RODAM study that was conducted among Ghanaian adults aged 25–70 years residing in rural- and urban-Ghana and in London, Amsterdam and Berlin (n = 5659). MetSyn was defined according to the 2009 harmonized definition. Geographical locations were compared using age-standardized prevalence rates, and prevalence ratios (PRs), adjusted for age, education, physical activity, and smoking and stratified for sex.

Results

In men, the age-standardized prevalence of MetSyn was 8.3% in rural Ghana and showed a positive gradient through urban Ghana (23.6%, adjusted PR = 1.85, 95% confidence interval 1.17–2.92) to Europe, with the highest prevalence in Amsterdam (31.4%; PR = 4.45, 2.94–6.75). In women, there was a rural-to-urban gradient in age-standardized MetSyn prevalence (rural Ghana 25%, urban Ghana 34.4%, PR = 1.38, 1.13–1.68), but small differences in MetSyn prevalence between urban-Ghanaian and European-Ghanaian women (Amsterdam 38.4%; London 38.2%).

Conclusion

MetSyn is highly prevalent in Ghana as well as in Ghanaian migrants in Europe. To assist prevention efforts, further research is needed to understand the mechanisms driving the geographical differences in MetSyn prevalence between migrant and non-migrant Ghanaians.

Success factors in high-effect, low-cost eHealth programs for patients with hypertension: a systematic review and meta-analysis

Background

eHealth programs can lower blood pressure but also drive healthcare costs. This study aims to review the evidence on the effectiveness and costs of eHealth for hypertension and assess commonalities in programs with high effect and low additional cost.

Results

Overall, the incremental decrease in systolic blood pressure using eHealth, compared to usual care, was 3.87 (95% confidence interval (CI) 2.98–4.77) mmHg at 6 months and 5.68 (95% CI 4.77–6.59) mmHg at 12 months’ follow-up. High intensity interventions were more effective, resulting in a 2.6 (95% CI 0.5–4.7) (at 6 months) and 3.3 (95% CI 1.4–5.1) (at 12 months) lower systolic blood pressure, but were also more costly, resulting in €170 (95% CI 56–284) higher costs at 6 months and €342 (95% CI 128–556) at 12 months. Programs that included a high volume of participants showed €203 (95% CI 99–307) less costs than those with a low volume at 6 months, and €525 (95% CI 299–751) at 12 months without showing a difference in systolic blood pressure. Studies that implemented eHealth as a partial replacement, rather than addition to usual care, were also less costly (€119 (95% CI –38–201 at 6 months) and €346 (95% CI 261–430 at 12 months)) without being less effective. Evidence on eHealth programs for hypertension is ambiguous, heterogeneity on effectiveness and costs is high ( I2 = 56–98%).

Conclusion

Effective eHealth with limited additional costs should focus on high intensity interventions, involve a large number of participants and use eHealth as a partial replacement for usual care.

Higher prevalence of peripheral arterial disease in Ghana compared to Ghanaian migrants in Europe: The RODAM study

BACKGROUND

Evidence suggests that the burden of peripheral artery disease (PAD) is rising more rapidly than other forms of cardiovascular diseases in sub-Saharan Africa, but the extent to which they differ between rural and urban settings in Africa and upon migration to Europe is unknown. We assessed the burden of PAD among Ghanaians living in rural- and urban-Ghana and Ghanaian migrants living in three European countries.

METHODS

Cross-sectional analyses of baseline data from the multicenter Research on Obesity and Diabetes among African Migrants (RODAM) study were done. Data from 5516 participants living in Europe (1487 Amsterdam, 546 Berlin, 1047 London) and Ghana [1419 urban and 1017 rural] aged 25-70years were included. PAD was defined as ankle brachial index≤0.90. Comparisons among sites were made using logistic regression analysis.

RESULTS

The age-standardized prevalence of PAD was higher in Ghanaians living in rural [7.52%, 95% CI = 5.87-9.51] and urban [8.93%, 7.44-10.64] Ghana than for their compatriots living in Europe [5.70%, 4.35-7.35 for London; 3.94%, 2.96-5.14 for Amsterdam; and 0.44%, 0.05-1.58 for Berlin]. The differences persisted even after adjustment for age, sex, education and the conventional cardiovascular risk factors [adjusted odds ratio = 3.16, 95% CI = 2.16-4.61, p < .001 for rural-Ghana; and 2.93, 1.87-4.58, p < .00 for urban-Ghana, compared with Ghanaian migrants in Europe].

CONCLUSIONS

Our study shows that Ghanaians living in Ghana have higher prevalence of PAD than their migrant compatriots. Further work is needed to identify potential factors driving the high prevalence of PAD among non-migrant Ghanaians to assist interventions aimed at reducing PAD burden.