Explaining population trends in cardiovascular risk: A comparative analysis of health transitions in South Africa and England
Lead Research Organisation:
University of Greenwich
Department Name: ILD, School of Human Sciences, FEHHS
Abstract
This study uses existing data to identify drivers of recent health transitions in South Africa compared to England. The global burden of non-communicable diseases (NCDs) on health is increasing. Cardiovascular diseases (CVD) in particular are the leading causes of death globally and often share characteristics with many major NCDs. Namely, they tend to increase with age and are influenced by behavioural factors such as diet, exercise and smoking. 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 (eg, South Africa) compared to those that exemplified models of 'epidemiologic transition' (eg, England) can generate knowledge on where resources may best be directed to reduce the burden of disease.
In the middle-income country of South Africa, CVD is the second leading cause of death after HIV/AIDS and tuberculosis (TB). Moreover, many of the known risk factors for NCDs like CVD are highly prevalent. Rates of hypertension are high, with recent estimates suggesting that over 40% of adults have high blood pressure. Around 60% of women and 30% of men over 15 are overweight in South Africa. In addition, excessive alcohol consumption, a risk factor for many chronic diseases, is high, with over 30% of men aged 15 and older having engaged in heavy episodic drinking within a 30-day period. Nevertheless, infectious diseases such as HIV/AIDS remain the leading cause of death, though many with HIV/AIDS and TB also have NCDs.
In high-income countries like England, by contrast, NCDs such as CVD have been the leading causes of death since the mid-1900s. However, CVD and risk factors such as hypertension have been declining in recent decades due to increased prevention and treatment.
The major drivers of change in disease burden have been attributed to factors including ageing, improved living standards, urbanisation, lifestyle change, and reduced infectious disease. Together, these changes are often referred to as the epidemiologic transition. However, recent research has questioned whether epidemiologic transition theory accurately describes the experience of many low- and middle-income countries or, in fact, of high-income nations such as England. Furthermore, few studies have empirically tested the relative contributions of demographic, behavioural, health and economic factors to trends in disease burden and risk, particularly on the African continent. In addition, many social and environmental factors are overlooked in this research.
To address these gaps, our study will use population measurements of CVD risk derived from surveys in South Africa over nearly 20 years in order to examine whether and to what extent demographic, behavioural, environmental, medical, social and other factors contribute to recent health trends and transitions. We will compare these trends to those occurring in England over the same time period. Thus, this analysis seeks to illuminate the drivers of health transitions in a country which is assumed to still be 'transitioning' to a chronic disease profile but which continues to have a high infectious disease burden (South Africa) as compared to a country which is assumed to have already transitioned following epidemiological transition theory (England). The analysis will employ modelling techniques on pooled cross-sectional data to examine how various factors explain the variation in CVD risk over time in representative population samples from South Africa and England.
The results of this analysis may help to identify some of the main contributors to recent changes in CVD risk in South Africa and England. Such information can be used to pinpoint potential areas for intervention, such as social policy and services, thereby helping to set priorities for governmental and nongovernmental action to control the CVD epidemic and improve health.
In the middle-income country of South Africa, CVD is the second leading cause of death after HIV/AIDS and tuberculosis (TB). Moreover, many of the known risk factors for NCDs like CVD are highly prevalent. Rates of hypertension are high, with recent estimates suggesting that over 40% of adults have high blood pressure. Around 60% of women and 30% of men over 15 are overweight in South Africa. In addition, excessive alcohol consumption, a risk factor for many chronic diseases, is high, with over 30% of men aged 15 and older having engaged in heavy episodic drinking within a 30-day period. Nevertheless, infectious diseases such as HIV/AIDS remain the leading cause of death, though many with HIV/AIDS and TB also have NCDs.
In high-income countries like England, by contrast, NCDs such as CVD have been the leading causes of death since the mid-1900s. However, CVD and risk factors such as hypertension have been declining in recent decades due to increased prevention and treatment.
The major drivers of change in disease burden have been attributed to factors including ageing, improved living standards, urbanisation, lifestyle change, and reduced infectious disease. Together, these changes are often referred to as the epidemiologic transition. However, recent research has questioned whether epidemiologic transition theory accurately describes the experience of many low- and middle-income countries or, in fact, of high-income nations such as England. Furthermore, few studies have empirically tested the relative contributions of demographic, behavioural, health and economic factors to trends in disease burden and risk, particularly on the African continent. In addition, many social and environmental factors are overlooked in this research.
To address these gaps, our study will use population measurements of CVD risk derived from surveys in South Africa over nearly 20 years in order to examine whether and to what extent demographic, behavioural, environmental, medical, social and other factors contribute to recent health trends and transitions. We will compare these trends to those occurring in England over the same time period. Thus, this analysis seeks to illuminate the drivers of health transitions in a country which is assumed to still be 'transitioning' to a chronic disease profile but which continues to have a high infectious disease burden (South Africa) as compared to a country which is assumed to have already transitioned following epidemiological transition theory (England). The analysis will employ modelling techniques on pooled cross-sectional data to examine how various factors explain the variation in CVD risk over time in representative population samples from South Africa and England.
The results of this analysis may help to identify some of the main contributors to recent changes in CVD risk in South Africa and England. Such information can be used to pinpoint potential areas for intervention, such as social policy and services, thereby helping to set priorities for governmental and nongovernmental action to control the CVD epidemic and improve health.
Organisations
- University of Greenwich (Lead Research Organisation)
- University College London (Collaboration)
- Stellenbosch University (Collaboration)
- Medical Research Council of South Africa (MRC) (Collaboration)
- Africa Health Research Institute (Collaboration)
- Human Sciences Research Council (HSRC) (Collaboration)
- South African Medical Research Council (Project Partner)
- Health Systems Trust (Project Partner)
Publications
| Description | Preliminary results suggest that trends in cardiovascular risk scores have followed different patterns in South Africa and England from the period 1998 to 2017. In England a more consistent decline has been observed, which appears to be flattening in more recent years. In South Africa, a potential increase was observed during the first half of the period, followed by a flattening or decline in CVD risk scores. In both countries, the trends are largely attributable to changes in the distribution of systolic blood pressure (SBP). Antihypertensive use potentially contributes to this. Decreases in smoking have made some impact, although less so than SBP. On the other hand, body mass index and diabetes have largely moved in an opposing direction to CVD trends. Trends in CVD risk scores appear to differ by gender and age group. Males have higher CVD risk in both countries. There are inequalities by region and ethnicity. Other factors that appear to account for a large proportion of variation in CVD risk scores over time include education. Significant achievements to date include the development of a Stakeholder and User Advisory Group leading to potential collaborations; a data dashboard that has been created on the project website which allows users to visualise and map these trends and trends in individual risk factors over time; an invitation to guest advise a special article collection in the International Journal of General Medicine; harmonised datasets and code for national population surveys from South Africa and England; and two whole day research dissemination and knowledge exchange events organised in South Africa and England. |
| Exploitation Route | The code and datasets that we produce in this project will provide opportunities for other researchers and practitioners to use repeated cross-sections of nationally-representative surveys to easily analyse trends in health and social outcomes in South Africa and England without additional efforts to recreate datasets and harmonise variables. The findings of our research may also help to identify targets for interventions to reduce the burden of cardiovascular disease in South Africa and England. |
| Sectors | Education Healthcare Government Democracy and Justice |
| URL | http://www.exposeproject.net |
| Description | Our preliminary findings were disseminated in South Africa and England through two day-long hybrid research dissemination and knowledge exchange events. Participants included non-academics such as health practitioners/healthcare workers, policymakers/politicians, third sector organisations/charities/funders, undergraduate/postgraduate students, and industry/business. Post participation surveys of participants revealed several initial impacts of our findings. These included increased knowledge about CVD and its risk factors, changes in views and opinions, plans for future related activities, influencing decisions, and increased curiosity to learn about some of the topics discussed. |
| First Year Of Impact | 2023 |
| Sector | Education,Healthcare |
| Impact Types | Societal |
| Title | ExPoSE Dataset v0.1 |
| Description | A harmonised dataset consisting of records from the South African Demographic and Health Surveys 1998, 2003 and 2016; the South African National Health and Nutrition Examination Survey 2012; the National Income Dynamics Study 2008, 2010-11, 2012, 2014-15 and 2017; and the South African Study on Global Ageing and Adult Health 2007-8 and 2014. A complementary dataset consisting of Health Survey for England data from 1998, 2001-2003, 2005-2017 has also been completed for use in analyses and trends. Portions of the dataset and code will be deposited in DataFirst, HSRC and UK Data Service repositories for public access. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2022 |
| Provided To Others? | No |
| Impact | Impacts to be determined |
| Title | Statistical code for harmonising datasets |
| Description | Statistical code (Stata, SPSS and R) for harmonising the Health Survey for England and the South African national health and social surveys available through a GitHub repository. Code for producing estimates is also available through GitHub. |
| Type Of Material | Computer model/algorithm |
| Year Produced | 2022 |
| Provided To Others? | Yes |
| Impact | To be determined |
| URL | https://github.com/AnnibaleCois/expose_code |
| Description | Collaboration and mentorship for Ms Meseret Mamo |
| Organisation | University of Stellenbosch |
| Country | South Africa |
| Sector | Academic/University |
| PI Contribution | We have been building the research capacity of master's graduate of Stellenbosch University, Meseret, on research activities including recoding data, data analysis and developing a manuscript for publication. |
| Collaborator Contribution | She has contributed in helping to recode variables in the 2007/8 South African Study on Global Ageing and Health (SAGE) for inclusion in our harmonised dataset as well as exploring data from the Vukuzazi study. |
| Impact | Outputs and outcomes include statistical code for the harmonisation of SAGE survey data from South Africa as well as preliminary analyses of the Vukuzazi dataset from the Africa Health Research Institute. Meseret has gone on to commence a PhD. |
| Start Year | 2022 |
| Description | Collaboration with African Health Research Institute |
| Organisation | Africa Health Research Institute |
| Country | South Africa |
| Sector | Charity/Non Profit |
| PI Contribution | Capacity building of African researchers and students and exploration of Vukuzazi data to examine assocations between TB, HIV/AIDS and CVD risk. |
| Collaborator Contribution | Provision of access to the Vukuzazi data for research and capacity building of African researchers and students as well as participation in the ExPoSE Stakeholder and User Advisory Group. |
| Impact | Preliminary analyses of the data were conducted by an early career researcher with the guidance of the research team. |
| Start Year | 2022 |
| Description | Collaboration with Health and Social Surveys Research Group (HSSRG), UCL |
| Organisation | University College London |
| Department | Institute of Epidemiology and Health Care |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | The research team proposed the collaboration and scope of work and identified Health Survey for England (HSE) surveys and variables to harmonise and analyse across the survey years. Dr Adjaye-Gbewonyo recoded the harmonised variables for the comparative analysis with South Africa. Drs Adjaye-Gbewonyo and Cois contributed to a draft manuscript describing the methodology of the data harmonisation and also presented at HSE seminars. |
| Collaborator Contribution | Members of the HSSRG at UCL (Dr Shaun Scholes) extracted the variables and coded and appended them into a compiled dataset and provided input on technical details of the HSE and identifying variables. Prof Jenny Mindell, Alison Moody and Jennifer Ng also contributed intellectually to the collaboration by providing input on technical details of the HSE and identifying variables. Dr Scholes led the drafting of a manuscript describing the methodology of the data harmonisation. Dr Scholes and Prof Mindell participated in the ExPoSE Stakeholder and User Advisory group meetings and presented at the ExPoSE Research Dissemination and Knowledge Exchange event in London. |
| Impact | A harmonised repeated cross-sectional Health Survey for England dataset from 1998 to 2017 was created as well as a description of the methods used to create the dataset. The code to harmonise the data is being made publicly available on the ExPoSE project website via GitHub as well as through other data repositories. Preliminary analyses were also run and these have been disseminated to stakeholders, users and other interested parties through presentations and in writing. |
| Start Year | 2021 |
| Description | Collaboration with Human Sciences Research Council |
| Organisation | Human Sciences Research Council (HSRC) |
| Country | South Africa |
| Sector | Charity/Non Profit |
| PI Contribution | Intended deposit of our dataset in their data repository. Intended research publications. |
| Collaborator Contribution | Provision of additional variables from the SANHANES survey. Participation in our Research Dissemination and Knowledge Exchange Event in Stellenbosch South Africa, 11th August 2023 |
| Impact | Intended deposit of our harmonised dataset in their repository. Intended research publications. |
| Start Year | 2022 |
| Description | Collaboration with Stellenbosch University |
| Organisation | University of Stellenbosch |
| Department | Faculty of Medicine and Health Sciences |
| Country | South Africa |
| Sector | Academic/University |
| PI Contribution | Dr Adjaye-Gbewonyo and Dr Cois are collaborating on the Explaining Population Trends in Cardiovascular Risk: A Comparative Analysis of Health Transitions in South Africa and England (ExPoSE) project. Dr Adjaye-Gbewonyo made a research visit to Stellenbosch University, Cape Town, South Africa to work with Dr Annibale Cois on data analysis for the South African and England datasets and the public engagement and dissemination website for the ExPoSE project. Dr Adjaye-Gbewonyo helped to organise a dissemination event at Stellenbosch. |
| Collaborator Contribution | Dr Annibale Cois made a hosted visit to the University of Greenwich Institute for Lifecourse Development in 2022 to work with Dr Kafui Adjaye-Gbewonyo on finalising the harmonisation of the first ExPoSE South Africa dataset as well as to work with the Health and Social Surveys Research Group at University College London on the Health Survey for England datasets. Dr Cois returned to Greenwich in 2023 for our research dissemination event which he helped to organise. |
| Impact | Dr Cois has been appointed as a Visiting Fellow of the Institute for Lifecourse Development where he gave a Public Lecture on his work with the South African Comparative Research Assessment. Dr Adjaye-Gbewonyo gave a talk at the Division of Health Systems and Public Health on her research on income inequality, social capital and risk for chronic disease in South Africa and has been nominated for an affiliation as an Extraordinary member of Stellenbosch University. Research dissemination and knowledge exchange events have been held at both institutions. |
| Start Year | 2021 |
| Description | Special Collection |
| Organisation | Medical Research Council of South Africa (MRC) |
| Country | South Africa |
| Sector | Public |
| PI Contribution | Dr Kafui Adjaye-Gbewonyo and Dr Annibale Cois developed a special collection entitled, 'The global epidemic of cardiometabolic disease: Risks, trends, explanations, and implications' for the International Journal of General Medicine, an open-access Dove Press journal which is part of the Taylor and Francis group. Drs Adjaye-Gbewonyo and Cois also initiated a list of potential contributors to the collection and contacted them to invite contributions. |
| Collaborator Contribution | Dr Andre Pascal Kengne, Director of the Non-Communicable Diseases Research Unit at South African Medical Research Council (SAMRC), contributed as a Guest Advisor, including by revising the article collection proposal. |
| Impact | This collection did not have enough submissions for publication by the deadline. |
| Start Year | 2022 |
| Description | Attendance at Accelerating progress on cardiovascular disease |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | Dr Adjaye-Gbewonyo attended this event organised by the King's Fund in which she networked with other attendees, speakers and participants. Attendance at the event resulted in collaboration for the ExPoSE research dissemination and knowledge exchange event in London, including panellists and presenters. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://www.kingsfund.org.uk/events/accelerating-progress-cardiovascular-disease |
| Description | Cardiovascular Disease in South Africa Indaba |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Policymakers/politicians |
| Results and Impact | Dr Annibale Cois was invited to the National Department of Health Indaba on Non-Communicable Diseases: Cardiovascular Disease in South Africa in collaboration with the South African Heart Association, Southern African Hypertension Society, and the Heart and Stroke Foundation of South Africa. Dr Cois attended the event and represented the ExPoSE project. |
| Year(s) Of Engagement Activity | 2022 |
| Description | Centre for Chronic Illness and Ageing Meeting |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Professional Practitioners |
| Results and Impact | We presented a summary of the project, our activities to date and some preliminary results and future plans to the Centre for Chronic Illness and Ageing meetings at University of Greenwich in March 2021 and May 2022. |
| Year(s) Of Engagement Activity | 2021,2022 |
| Description | ExPoSE Research Dissemination and Knowledge Exchange Event, South Africa |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | The Division of Health Systems and Public Health at Stellenbosch University organised a research dissemination and knowledge sharing event to launch the findings of the project, Explaining Population Trends in Cardiovascular Risk: A Comparative Analysis of Health Transitions in South Africa and England (ExPoSE). The event was held on the 11th of August at the Stellenbosch Institute for Advanced Study (Stias) Wallenberg Research Centre, 10 Marais Road, Stellenbosch, South Africa, from 9 AM to 4 PM, and included remote participation (via Microsoft Teams). Impacts reported by participants included enhanced knowledge about CVD and its risk factors, changes in views or opinions, plans for future related activities, influencing decisions and plans for future related activities. For example, one outcome of the event was a collaboration between the PI, international co-investigator and an attendee and her colleagues to bid for funds for a grant for another related research project. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://www.exposeproject.net/blog/20230813/ |
| Description | ExPoSE Stakeholder and User Advisory Group Meeting |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | On the 16th of November 2021, we held the First Stakeholder and User Advisory Group Meeting for the ESRC-funded research project Explaining Population Trends in Cardiovascular Risk: A Comparative Analysis of Health Transitions in South Africa and England (ExPoSE). The Second Stakeholder and User Advisory Group Meeting was held on the 4th of October 2022. Members of the following organisations are represented on the Advisory Group: ? Departments of Health: South Africa National Department of Health ? Academic: University of Greenwich, Stellenbosch University, University College London, University of the Witwatersrand, King's College London/University of Lausanne ? Research: South African Medical Research Council, Human Sciences Research Council, Africa Health Research Institute, NatCen Social Research ? Civil society: Health Systems Trust, Heart & Stroke Foundation of South Africa ? Healthcare: Charlotte Maxeke Hospital, Khayelitsha District Hospital, Council for Medical Schemes ? Data hosting: DataFirst, UK Data Service ? Patient groups: Stroke Survivors Foundation, South Africa |
| Year(s) Of Engagement Activity | 2021,2022 |
| Description | ExPoSE website |
| Form Of Engagement Activity | Engagement focused website, blog or social media channel |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Public/other audiences |
| Results and Impact | The project website was developed by the research team and designed by Dr Annibale Cois. It includes information about the project; team members, stakeholders and collaborators; news and updates; outputs such as presentations and links to our code; as well as a data dashboard that allows people to visualise and summarise our data. The purpose is to disseminate the research in a rapid manner and in an easily-digestible format for the public. It also aims to help foster collaboration. |
| Year(s) Of Engagement Activity | 2022 |
| URL | http://www.exposeproject.net |
| Description | Explaining Population Trends in Cardiovascular Risk: A Research Dissemination and Knowledge Exchange Event |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | This event was hosted by the Institute for Lifecourse Development at the University of Greenwich and aimed to launch the findings and outputs of the project, Explaining Population Trends in Cardiovascular Risk: A Comparative Analysis of Health Transitions in South Africa and England (ExPoSE) to the public and stakeholders in England and initiate discussions about their implications and translation into action. The event was also designed to showcase the ExPoSE harmonised dataset, code and a data dashboard to participants. This event targeted researchers, healthcare workers, civil society organisations, academics, public sector workers, media organisations, policymakers, students and patient groups with an interest in cardiovascular health or non-communicable diseases more generally. Participants reported impacts such as enhancements in knowledge, changes of views, influence on future plans and decisions and sparking curiosity to learn more. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://www.exposeproject.net/blog/20230904_1/ |
| Description | Living with Chronic Illness as We Age |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | Dr Adjaye-Gbewonyo participated in this hybrid research dissemination and knowledge exchange event organised by the Centre for Chronic Illness and Ageing, University of Greenwich and sponsored by the British Society of Gerontology on the 3rd of May 2023. Approximately 35 attendees participated. The event also produced a highlight video geared toward the lay public which has garnered over 150 views. In addition, at least one attendee from the healthcare sector went on to participate in the ExPoSE project dissemination event in London in September. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://www.youtube.com/watch?v=SCqw8cqsF74&lc=UgzFr3SwRIORwshcIzN4AaABAg |
| Description | Public Health Association of South Africa |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | An abstract of work led by Dr Cois on the Burden of disease averted by antihypertensive treatment: South Africa 1998-2017 was accepted to the Public Health Association of South Africa (PHASA) 2023 meeting. PHASA is a non-profit organisation whose members include researchers, epidemiologists, public health medicine specialists, academics, and public sector employees at national, provincial and local levels. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://phasa.samrc.ac.za/programme.html |
| Description | The Institute for Lifecourse Development Showcase Event: This is our Time |
| Form Of Engagement Activity | Participation in an open day or visit at my research institution |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Third sector organisations |
| Results and Impact | This was an event showcasing research done by members of the Institute for Lifecourse Development, University of Greenwich. Partners from UK organisations were in attendance. |
| Year(s) Of Engagement Activity | 2023 |
| Description | UCL Health Survey for England Seminar |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Dr Adjaye-Gbewonyo and Dr Cois gave a presentation on "Comparing cardiovascular risk trends in England and South Africa, using health and social survey data" to the University College London Health Survey for England Seminar in May 2022, which included participants from NHS Digital, NatCen Social Research, academics and postgraduate students. In September 2023, Dr Cois presented our talk, 'CVD risk trends in South Africa and England: Findings from the ExPoSE project' at the seminar which had a similar audience to the previous year. |
| Year(s) Of Engagement Activity | 2022,2023 |
| URL | https://www.exposeproject.net/blog/20230921/ |