Income inequality and cardiovascular disease risk factors in a highly unequal country: a fixed-effects analysis from South Africa

Associations between dimensions of the social environment and cardiometabolic risk factors: Systematic review and meta-analysis

Aim

The social environment (SE), including social contacts, norms and support, is an understudied element of the living environment which impacts health. We aim to comprehensively summarize the evidence on the association between the SE and risk factors of cardiometabolic disease (CMD).

Methods

We performed a systematic review and meta-analysis based on studies published in PubMed, Scopus and Web of Science Core Collection from inception to 16 February 2021. Studies that used a risk factor of CMD, e.g., HbA1c or blood pressure, as outcome and social environmental factors such as area-level deprivation or social network size as independent variables were included. Titles and abstracts were screened in duplicate. Study quality was assessed using the Newcastle-Ottawa Scale. Data appraisal and extraction were based on the study protocol published in PROSPERO. Data were synthesized through vote counting and meta-analyses.

Results

From the 7521 records screened, 168 studies reported 1050 associations were included in this review. Four meta-analyses based on 24 associations suggested that an unfavorable social environment was associated with increased risk of cardiometabolic risk factors, with three of them being statistically significant. For example, individuals that experienced more economic and social disadvantage had a higher "CVD risk scores" (OR = 1.54, 95%CI: 1.35 to 1.84). Of the 458 associations included in the vote counting, 323 (71%) pointed towards unfavorable social environments being associated with higher CMD risk.

Conclusion

Higher economic and social disadvantage seem to contribute to unfavorable CMD risk factor profiles, while evidence for other dimensions of the social environment is limited.

Hypertension care cascades and reducing inequities in cardiovascular disease in low- and middle-income countries

Improving hypertension control in low- and middle-income countries has uncertain implications across socioeconomic groups. In this study, we simulated improvements in the hypertension care cascade and evaluated the distributional benefits across wealth quintiles in 44 low- and middle-income countries using individual-level data from nationally representative, cross-sectional surveys. We raised diagnosis (diagnosis scenario) and treatment (treatment scenario) levels for all wealth quintiles to match the best-performing country quintile and estimated the change in 10-year cardiovascular disease (CVD) risk of individuals initiated on treatment. We observed greater health benefits among bottom wealth quintiles in middle-income countries and in countries with larger baseline disparities in hypertension management. Lower-middle-income countries would see the greatest absolute benefits among the bottom quintiles under the treatment scenario (29.1 CVD cases averted per 1,000 people living with hypertension in the bottom quintile (Q1) versus 17.2 in the top quintile (Q5)), and the proportion of total CVD cases averted would be largest among the lowest quintiles in upper-middle-income countries under both diagnosis (32.0% of averted cases in Q1 versus 11.9% in Q5) and treatment (29.7% of averted cases in Q1 versus 14.0% in Q5) scenarios. Targeted improvements in hypertension diagnosis and treatment could substantially reduce socioeconomic-based inequalities in CVD burden in low- and middle-income countries.

Association of Income Level and Ischemic Heart Disease: Potential Role of Walkability

BACKGROUND

Association of Income Level and Ischemic Heart Disease: Potential Role of Walkability Association of ischemic heart disease (adjusted for traditional risk factors and socioeconomics variables) and income level (A), and walkability z-score (B), and association of walkability z-score and income level (C).

BACKGROUND

Socioeconomic status has been linked to ischemic heart disease (IHD). High-income neighborhoods may expose individuals to a walking-promoting built environment for daily activities (walkability). Data from the association between income and IHD is lacking in middle-income countries. It is also uncertain whether walkability mediates this association.

OBJECTIVES

To investigate whether income is associated with IHD in a middle-income country and whether neighborhood walkability mediates the income-IHD association.

METHODS

This cross-sectional study evaluated 44,589 patients referred for myocardial perfusion imaging (SPECT-MPI). Income and walkability were derived from participants' residential census tract. Walkability quantitative score combined 4 variables: street connectivity, residential density, commercial density, and mixed land use. IHD was defined by abnormal myocardial perfusion during a SPECT-MPI study. We used adjusted mixed effects models to evaluate the association between income level and IHD, and we performed a mediation analysis to measure the percentage of the income-IHD association mediated by walkability. We considered p values below 0.01 as statistically significant.

RESULTS

From 26,415 participants, those living in the lowest-income tertile census tract were more physically inactive (79.1% versus 75.8% versus 72.7%) when compared to higher-income tertile census tracts (p < 0.001). Income was associated with IHD (odds ratio: 0.91 [95% confidence interval: 0.87 to 0.96] for each 1,000.00 international dollars increase in income) for both men and women equally (p for interaction = 0.47). Census tracts with a higher income were associated with better walkability (p < 0.001); however, walkability did not mediate the income-IHD association (percent mediated = -0.3%).

CONCLUSIONS

Income was independently associated with higher prevalence of IHD in a middle-income country irrespective of gender. Although walkability was associated with census tract income, it did not mediate the income-IHD association.

Comprehensive metrological and content analysis of the income inequality research in health field: A bibliometric analysis

The association between income inequality in a society and the poor health status of its people has attracted the attention of researchers from multiple disciplines. Based on the ISI Web of Science database, bibliometric methods were used to analyze 546 articles related to income inequality research in health field published between 1997 and 2021. We found that the USA contributed most articles, the Harvard Univ was the most influential institution, Social Science & Medicine was the most influential journal, and Kawachi I was the most influential author; the main hotspots included the income inequality, income, health inequality, mortality, socioeconomic factors, concentration index, social capital, self-rated health, income distribution, infant mortality, and population health in 1997-2021; the cardiovascular disease risk factor, social capital income inequality, individual mortality risk, income-related inequalities, understanding income inequalities, income inequality household income, and state income inequality had been the hot research topics in 1997-2003; the self-assessed health, achieving equity, income-related inequalities, oral health, mental health, European panel, occupational class, and cardiovascular diseases had been the hot research topics in 2004-2011; the adolescent emotional problem, South Africa, avoidable mortality, rising inequalities, results from world health survey, working-age adult, spatial aggregation change, prospective study, and mental health-empirical evidence had been the hot research topics in 2012-2021; there were 11 articles with strong transformation potential during 2012-2021. The research results of this paper are helpful to the scientific understanding of the current status of income inequality research in health field.

Explaining population trends in cardiovascular risk: protocol for a comparative analysis of health transitions in South Africa and England using nationally representative survey data

INTRODUCTION

Cardiovascular diseases (CVD) are the leading cause of death globally and share determinants with other major non-communicable diseases. Risk factors for CVD are routinely measured in population surveys and thus provide an opportunity to study health transitions. Understanding the drivers of health transitions in countries that have not followed expected paths compared with those that exemplified models of 'epidemiologic transition', such as England, can generate knowledge on where resources may best be directed to reduce the burden of disease. This study aims to examine the notions of epidemiological transition by identifying and quantifying the drivers of change in CVD risk in a middle-income African setting compared with a high-income European setting.

METHODS AND ANALYSIS

This is a secondary joint analysis of data collected within the scope of multiple population surveys conducted in South Africa and England between 1998 and 2017 on nationally representative samples of the adult population. The study will use a validated, non-laboratory risk score to estimate and compare the distribution of and trends in total CVD risk in the population. Statistical modelling techniques (fixed-effects and random-effects multilevel regression models and structural equation models) will be used to examine how various factors explain the variation in CVD risk over time in the two countries.

ETHICS AND DISSEMINATION

This study has obtained approval from the University of Greenwich (20.5.6.8) and Stellenbosch University (X21/09/027) Research Ethics Committees. It uses anonymised microdata originating from population surveys which received ethical approval from the relevant bodies, with no additional primary data collection. Results of the study will be disseminated through (1) peer-reviewed articles in open access journals; (2) policy briefs; (3) conferences and meetings; and (4) public engagement activities designed to reach health professionals, governmental bodies, civil society and the lay public. A harmonised data set will be made publicly available through online repositories.

Factors Associated With Hope and Quality of Life in Patients With Coronary Artery Disease

BACKGROUND

Psychological resources such as hope have been suggested to affect quality of life (QoL) positively in patients with heart disease. However, little information regarding the relationship between these two constructs is available.

PURPOSE

This work was aimed at examining the factors associated with hope and QoL in patients with coronary artery disease.

METHODS

In this descriptive work, perceived QoL and hope were assessed in 500 patients with heart disease. The information was collected using the McGill QoL Questionnaire, demographic variables, and the Herth Hope Index. The Pearson correlation test and general linear model were used to examine correlations through SPSS Version 22.

RESULTS

A considerable correlation was discovered between QoL and hope (r = .337, p < .001). Multivariate analyses with regression revealed that religious beliefs and social support both had significant and positive effects on the total perceived hope of patients and that patient age had a considerable negative impact on QoL (p < .05). None of these factors had a significant impact on hope (p < .05). In addition, the total QoL had a significant and positive effect on patient feelings and thoughts, whereas the physical problems component of QoL had a significant and negative effect on hope (p < .05). Participants with higher levels of education reported more hope.

CONCLUSIONS

QoL relates significantly to self-perceived hope in patients. Understanding QoL and hopefulness in patients with coronary artery disease has implications for nurses and other healthcare professionals.

Single motherhood, social independence and non-communicable disease (NCD) outcomes among young females (15-24 years old) in South Africa

Background: Non-communicable diseases (NCDs) acquired during youth follow into and affect adulthood. The association between young mother’s social independence and NCD status is of policy interest due to its effect on economic and social development. This study aimed to determine the causal relationship between social independence and NCD outcomes among young, single mothers in South Africa. Methods: Data from the South African National Income Dynamics Survey (NIDS) in 2008 and 2017 was used to determine if single mothers developed hypertension, diabetes or asthma by various indicators of social independence, including highest level of education and employment status. The sample was initially made-up of unmarried females (15-24 years old) without any children in 2008. Both fertility and social independence was followed-up to 2017. Results: In total, 66 young females developed an NCD by 2017 and 87% (n=57) of these women had a child in the interim period. Employment of young females increased from 4.78% in 2008 to 37.79% in 2017, but completion of secondary or tertiary education declined from 67.94% in 2008 to 56.01% in 2017. In addition, half (50.88%) of the young females were partially independent by 2017, with only 11.03% being fully independent at this time. Finally, logistic regression results showed that the likelihood of developing an NCD increased if young females with children were not socially independent. Conclusions: The relationship between social independence and NCDs suggest that policies and programmes in South Africa need to incorporate socioeconomic status as a determinant of disease and in particular, need to address socioeconomic indicators as additive measures and not autonomous indicators.

Risk factors of deaths related to cardiovascular diseases in World Health Organization (WHO) member countries

This study aims to identify the risk factors affecting deaths related to cardiovascular diseases. The research population comprised of 194 World Health Organization (WHO) member countries, but the data analysis was conducted with the data from 152 countries as 42 of them do not have any data on study variables. Multivariable regression analysis was utilised for this study to analyse the effect of factors regarding metabolism, lifestyle, economic, socio-demographic and health system on the cardiovascular diseases related to deaths. As a result of regression analysis, the number of deaths related to cardiovascular diseases increases with the increase in blood pressure (p < .001), blood glucose (p = .032), obesity rate (p < .001), salt consumption (p < .001), GINI index (p = .002) and dependent age ratio (p < .001); the frequency of cardiovascular disease-related deaths is higher in the countries within low (p < .001) and high (p < .001) middle-income levels; yet, the number of deaths based on cardiovascular diseases diminishes with the increase in the number of doctors (p = .005) and health expenditures per capita (p = .044). The research findings are considered to guide the countries in the determination of their steps towards the prevention of deaths related to cardiovascular diseases.

Single motherhood, social independence and non-communicable disease (NCD) outcomes among young females (15-24 years old) in South Africa

Background: Non-communicable diseases (NCDs) acquired during youth follow into and affect adulthood. The association between young mother’s social independence and NCD status is of policy interest due to its effect on economic and social development. This study aimed to determine the causal relationship between social independence and NCD outcomes among young, single mothers in South Africa. Methods: Data from the South African National Income Dynamics Survey (NIDS) in 2008 and 2017 was used to determine if single mothers developed hypertension, diabetes or asthma by various indicators of social independence, including highest level of education and employment status. The sample was initially made-up of unmarried females (15-24 years old) without any children in 2008. Both fertility and social independence was followed-up to 2017. Results: In total, 66 young females developed an NCD by 2017 and 87% (n=57) of these women had a child in the interim period. Employment of young females increased from 4.78% in 2008 to 37.79% in 2017, but completion of secondary or tertiary education declined from 67.94% in 2008 to 56.01% in 2017. In addition, half (50.88%) of the young females were partially independent by 2017, with only 11.03% being fully independent at this time. Finally, logistic regression results showed that the likelihood of developing an NCD increased if young females with children were not socially independent. Conclusions: The relationship between social independence and NCDs suggest that policies and programmes in South Africa need to incorporate socioeconomic status as a determinant of disease and in particular, need to address socioeconomic indicators as additive measures and not autonomous indicators.

Single motherhood, social independence and non-communicable disease (NCD) outcomes among young females (15-24 years old) in South Africa

Background: Non-communicable diseases (NCDs) acquired during youth follow into and affect adulthood. The association between young mother’s social independence and NCD status is of policy interest due to its effect on economic and social development. This study aimed to determine the causal relationship between social independence and NCD outcomes among young, single mothers in South Africa. Methods: Data from the South African National Income Dynamics Survey (NIDS) in 2008 and 2017 was used to determine if single mothers developed hypertension, diabetes or asthma by various indicators of social independence, including highest level of education and employment status. The sample was initially made-up of unmarried females (15-24 years old) without any children in 2008. Both fertility and social independence was followed-up to 2017. Results: In total, 66 young females developed an NCD by 2017 and 87% (n=57) of these women had a child in the interim period. Employment of young females increased from 4.78% in 2008 to 37.79% in 2017, but completion of secondary or tertiary education declined from 67.94% in 2008 to 56.01% in 2017. In addition, half (50.88%) of the young females were partially independent by 2017, with only 11.03% being fully independent at this time. Finally, logistic regression results showed that the likelihood of developing an NCD increased if young females with children were not socially independent. Conclusions: The relationship between social independence and NCDs suggest that policies and programmes in South Africa need to incorporate socioeconomic status as a determinant of disease and in particular, need to address socioeconomic indicators as additive measures and not autonomous indicators.

Using a mHealth system to recall and refer existing clients and refer community members with health concerns to primary healthcare facilities in South Africa: a feasibility study

Background: Lay health workers (LHWs) are critical in linking communities and primary healthcare (PHC) facilities. Effective communication between facilities and LHWs is key to this role. We implemented a mobile health (mHealth) system to improve communication and continuity of care for chronically ill clients. The system focused on requests from facility staff to LHWs to follow up clients and LHW referrals of people who needed care at a facility. We implemented the system in two rural and semi-rural sub-districts in South Africa.

Objective: To assess the feasibility of the mHealth system in improving continuity of care for clients in PHC in South Africa.

Method: We implemented the intervention in 15 PHC facilities. The clerks issued recalls to LHWs using a tablet computer. LHWs used smartphones to receive these requests, communicate with clerks and refer people to a facility. We undertook a mixed-methods evaluation to assess the feasibility of the mHealth system. We analysed recall and referral data using descriptive statistics. We used thematic content analysis to analyse qualitative data from semi-structured interviews with facility staff and a researcher fieldwork journal.

Results: Across the sub-districts, 2,204 clients were recalled and 628 (28%) of these recalls were successful. LHWs made 1,085 referrals of which 485 (45%) were successful. The main client group referred and recalled were children under 5 years. Qualitative data showed the impacts of facility conditions and interpersonal relationships on the mHealth system.

Conclusion: Using mHealth for recalls and referrals is probably feasible and can improve communication between LHWs and facility staff. However, the low success rates highlight the need to assess facility capacity beforehand and to integrate mHealth with existing health information systems. mHealth may improve communication between LHWs and facility staff, but its success depends on the health system capacity to incorporate these interventions.

A "Swiss paradox" in the United States? Level of spatial aggregation changes the association between income inequality and morbidity for older Americans

Although a preponderance of research indicates that increased income inequality negatively impacts population health, several international studies found that a greater income inequality was associated with better population health when measured on a fine geographic level of aggregation. This finding is known as a “Swiss paradox”. To date, no studies have examined variability in the associations between income inequality and health outcomes by spatial aggregation level in the US. Therefore, this study examined associations between income inequality (Gini index, GI) and population health by geographic level using a large, nationally representative dataset of older adults. We geographically linked respondents’ county data from the 2012 Behavioral Risk Factor Surveillance System to 2012 American Community Survey data. Using generalized linear models, we estimated the association between GI decile on the state and county levels and five population health outcomes (diabetes, obesity, smoking, sedentary lifestyle and self-rated health), accounting for confounders and complex sampling. Although state-level GI was not significantly associated with obesity rates (b = − 0.245, 95% CI − 0.497, 0.008), there was a significant, negative association between county-level GI and obesity rates (b = − 0.416, 95% CI − 0.629, − 0.202). State-level GI also associated with an increased diabetes rate (b = 0.304, 95% CI 0.063, 0.546), but the association was not significant for county-level GI and diabetes rate (b = − 0.101, 95% CI − 0.305, 0.104). Associations between both county-level GI and state-level GI and current smoking status were also not significant. These findings show the associations between income inequality and health vary by spatial aggregation level and challenge the preponderance of evidence suggesting that income inequality is consistently associated with worse health. Further research is needed to understand the nuances behind these observed associations to design informed policies and programs designed to reduce socioeconomic health inequities among older adults.

Explaining income-related inequalities in cardiovascular risk factors in Tunisian adults during the last decade: comparison of sensitivity analysis of logistic regression and Wagstaff decomposition analysis

BACKGROUND

It is important to quantify inequality, explain the contribution of underlying social determinants and to provide evidence to guide health policy. The aim of the study is to explain the income-related inequalities in cardiovascular risk factors in the last decade among Tunisian adults aged between 35 and 70 years old.

METHODS

We performed the analysis by applying two approaches and compared the results provided by the two methods. The methods were global sensitivity analysis (GSA) using logistic regression models and the Wagstaff decomposition analysis.

RESULTS

Results provided by the two methods found a higher risk of cardiovascular diseases and diabetes in those with high socio-economic status in 2005. Similar results were observed in 2016. In 2016, the GSA showed that education level occupied the first place on the explanatory list of factors explaining 36.1% of the adult social inequality in high cardiovascular risk, followed by the area of residence (26.2%) and income (15.1%). Based on the Wagstaff decomposition analysis, the area of residence occupied the first place and explained 40.3% followed by income and education level explaining 19.2 and 14.0% respectively. Thus, both methods found similar factors explaining inequalities (income, educational level and regional conditions) but with different rankings of importance.

CONCLUSIONS

The present study showed substantial income-related inequalities in cardiovascular risk factors and diabetes in Tunisia and provided explanations for this. Results based on two different methods similarly showed that structural disparities on income, educational level and regional conditions should be addressed in order to reduce inequalities.

Migration status and prevalence of diabetes and hypertension in Gauteng province, South Africa: effect modification by demographic and socioeconomic characteristics-a cross-sectional population-based study

INTRODUCTION

Evidence from low-income and middle-income countries suggests that migration status has an impact on health. However, little is known about the effect that migration status has on morbidity in sub-Saharan Africa. The aim of this study is to investigate the association between migration status and hypertension and diabetes and to assess whether the association was modified by demographic and socioeconomic characteristics.

METHODS

A Quality ofLife survey conducted in 2015 collected data on migration status and morbidity from a sample of 28 007 adults in 508 administrative wards in Gauteng province (GP). Migration status was divided into three groups: non-migrant if born in Gauteng province, internal migrant if born in other South African provinces, and external migrant if born outside of South Africa. Diabetes and hypertension were defined based on self-reported clinical diagnosis. We applied a recently developed original, stepwise-multilevel logistic regression of discriminatory accuracy to investigate the association between migration status and hypertension and diabetes. Potential effect modification by age, sex, race, socioeconomic status (SES) and ward-level deprivation on the association between migration status and morbidities was tested.

RESULTS

Migrants have lower prevalence of diabetes and hypertension. In multilevel models, migrants had lower odds of reporting hypertension than internal migrants (OR=0.86; 95% CI 0.78 to 0.95) and external migrant (OR=0.60; 95% CI 0.49 to 0.75). Being a migrant was also associated with lower diabetes prevalence than being an internal migrant (OR=0.84; 95% CI 0.75 to 0.94) and external migrant (OR=0.53; 95% CI 0.41 to 0.68). Age, race and SES were significant effect modifiers of the association between migration status and morbidities. There was also substantial residual between-ward variance in hypertension and diabetes with median OR of 1.61 and 1.24, respectively.

CONCLUSIONS

Migration status is associated with prevalence of two non-communicable conditions. The association was modified by age, race and SES. Ward-level effects also explain differences in association.

Chronic Ongoing Stressors and C-Reactive Protein: A Within-Person Study

Objectives: Literature suggests C-reactive protein (CRP)-as a marker of low-grade systemic inflammation-may mediate the linkage between chronic stressors and cardiometabolic conditions. Previous population-based reports are based on weak methodologies and may have yielded incorrect inferences. The current study examined linkages of within-person CRP variation with corresponding variation in stressor burdens. Method: Data were from the 2006, 2010, and 2014 waves of the U.S. Health and Retirement Study. Analysis was through unit fixed effects and first-difference estimators. Both gender-combined and gender-specific models were run. Results: In none of the analyses was CRP positively associated with chronic stressors. This was true among both genders, and in models of linear as well as nonlinear change. Results held in a series of separate robustness checks. Discussion: CRP may not mediate the social etiology of degenerative diseases. Population representative evidence of inflammation's role in these processes remains absent.

Changes in socio-economic status and lipoproteins in Chilean adolescents: a 16-year longitudinal study

OBJECTIVE

The present longitudinal study assessed whether changes in socio-economic status (SES) from infancy to adolescence were associated with plasma lipoprotein concentrations in adolescence, of which low HDL-cholesterol (HDL-C) and high LDL-cholesterol (LDL-C), TAG and total cholesterol (TC) concentrations are associated with higher cardiovascular risk.

DESIGN

SES, assessed using the modified Graffar Index, was calculated at 1, 5, 10 and 16 years. Principal components factor analysis with varimax rotation extracted two orthogonal SES factors, termed 'environmental capital' and 'social capital'. Generalized linear models were used to analyse associations between environmental and social capital at 1 and 16 years and outcomes (HDL-C, LDL-C, TAG, TC) at 16 years, as well as changes in environmental and social capital from 1-5, 5-10, 10-16 and 1-16 years, and outcomes at 16 years.

SETTING

Santiago, Chile.ParticipantsWe evaluated 665 participants from the Santiago Longitudinal Study enrolled at infancy in Fe-deficiency anaemia studies and examined every 5 years to age 16 years.

RESULTS

Social capital in infancy was associated with higher HDL-C in adolescence. Environmental capital in adolescence was associated with higher LDL-C and TC during adolescence. Changing environmental capital from 1-16 years was associated with higher LDL-C. Changing environmental capital from 1-5 and 1-16 years was associated with higher TC.

CONCLUSIONS

Improvements in environmental capital throughout childhood were associated with less healthy LDL-C and TC concentrations in adolescence. We found no evidence of associations between changing environmental capital and HDL-C or TAG, or changing social capital and HDL-C, LDL-C, TAG or TC.