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.
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 largely attributable to decreases in systolic blood pressure. In South Africa, an increase was observed during the first half of the period, followed by a flattening or decline in CVD risk scores. Trends in CVD risk scores appear to differ by gender and age group. 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; a special article collection in the International Journal of General Medicine guest advised by the research team and Prof Andre Kengne; and harmonised datasets and code for national population surveys from 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 | Healthcare |
URL | http://www.exposeproject.net |
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, 2003, 2005-2017 has been partially completed for use in analyses and trends. |
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 and R) for harmonising South African national health and social surveys and producing estimates available through a GitHub repository. |
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 guiding 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 | Statistical code |
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 surveys and variables to harmonise and analyse across the survey years. |
Collaborator Contribution | Members of the HSSRG at UCL (Dr Shaun Scholes, Prof Jenny Mindell, Alison Moody, Jennifer Ng) extracted the variables and coded and appended them into a compiled dataset and/or provided input on technical details of the HSE and identifying variables. |
Impact | A harmonised repeated cross-sectional Health Survey for England dataset from 1998 to 2017 is in progress as well as a description of the methods used to create the dataset. |
Start Year | 2021 |
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. |
Collaborator Contribution | Dr Annibale Cois made a hosted visit to the University of Greenwich Institute for Lifecourse Development 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. |
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. |
Start Year | 2021 |
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 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 | 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 | We 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 which included participants from NHS Digital, NatCen Social Research, academics and postgraduate students. |
Year(s) Of Engagement Activity | 2022 |