A research programme focusing on the socioeconomic value of an individual’s health

A complex relationship

The relationship between people’s health and socioeconomic factors

The greatest influences on people’s health are the social determinants of health – the social, cultural, political, economic, commercial and environmental factors that affect how people grow up, live, work and age. People living in deprived circumstances or with low levels of education have poorer physical and mental health. They live shorter lives and live more of their lives in poor health.

The relationship between socioeconomic factors and people’s health is complex: it is dynamic and multidirectional (Figure 5).

Figure 5: The dynamic relationship between health and socioeconomic factors

The multidirectional nature of the relationship is an opportunity to set up cycles of health and socioeconomic improvement. For example, keeping a child in good health could help them achieve their educational potential, increasing their chance of gaining good employment (red arrow). We know that good work is good for health (blue arrow).

However, cycles can also perpetuate health and socioeconomic inequalities. For example, a period of poor health can lead to a loss of work and income (red arrow). Low income can in turn lead to poorer health (blue arrow). Failure to invest in the maintenance and improvement of health via the social determinants of health risks such a cycle becoming established. Maximising health and socioeconomic potential requires a better understanding of the relationship.

There is a lack of evidence about the effect of people’s health and wellbeing on their socioeconomic circumstances (red arrow). Few studies have attempted to address the question of the socioeconomic value of maintaining good health across the life course. Where they have, unpicking the complex relationships has proven challenging.

Establishing causality

Understanding the relationships between health and socioeconomic factors is hindered by their complexity. The model of cause and effect is not simple or linear, and cannot be accurately described by the research methods and statistical models often used in population health research.

Health outcomes can be thought of as the consequence of numerous interactions between multiple interdependent parts of a connected whole. Such complex systems can mean that as one part of the system changes, another adapts – with potentially unexpected consequences. Complex systems are ‘defined by several properties, including emergence, feedback, and adaptation’.

It is relatively straightforward to demonstrate that different factors are associated with each other in individuals or populations, either at a single point in time or over a length of time. It can be tempting to assume that one factor causes the other. But association is not causation, and establishing whether a change in one factor causes a change in another is far more challenging. Attributing causality becomes particularly difficult when outcomes are distant in time from exposures, and multiple linked exposures and outcomes exist. To attribute causality, we first need to separate cause from effect, as well as the role of other factors at play (Figure 6).

Figure 6: Causal relationships

The evidence for the socioeconomic value of health

Existing UK evidence

The Health Foundation commissioned University College London’s Centre for Longitudinal Studies (CLS) to review the evidence on the effect health has on people’s socioeconomic outcomes and to identify what further research is needed.

UK research on the causal relationships between people’s health and their socioeconomic outcomes tends to be derived from longitudinal cohort studies. The cohorts are made up of people who were born at a given time and place and are followed up at intervals over the course of their lives. Data collection includes interviews, measurements and often blood samples. Cohort studies are rich sources of information about people’s lives, particularly health and socioeconomic factors.

The CLS review included longitudinal cohort studies that explored the effects of health on socioeconomic outcomes. The review looked at three life stages: up to 18 years, 18–50 years, and over 50 years of age. Studies were assessed in terms of quantity, quality, and consistency of findings (Figure 7). Overall, the evidence was found to be limited and inconclusive, due partly to a lack of studies and partly to inconsistent findings. The inconsistent findings were often the result of the studies using different methodologies and data.

Figure 7: Quantity, quality and consistency of evidence for the causal effect of physical and mental health on socioeconomic outcomes at three life stages

Key gaps in the evidence

The CLS review revealed large gaps in our understanding of the causal effect of health on people’s individual socioeconomic outcomes. It also found there was scope in the rich, detailed data available in UK longitudinal cohort studies for future research:

  • The effects of health on socioeconomic outcomes across the full lifespan could be assessed.
  • Comparisons across cohorts could be made to see if the effects of health are changing across generations.
  • Greater use could be made of the biomedical data already available in cohort studies.
  • Causal relationships could be further investigated using novel statistical methods.

On the basis of these findings, the Health Foundation called for research proposals to explore the social and economic value of an individual’s health. The details of the chosen projects are detailed below. We are also developing a further call for research proposals to address how the health of a population in a particular place can affect the social and economic outcomes of that place. The call will go out in 2019.

The Social and Economic Value of Health research programme

What is the research programme?

The Health Foundation is funding six research projects that aim to better understand the causal effect of health on socioeconomic outcomes at the individual level. The research projects draw on the UK longitudinal cohort studies to address many of the identified gaps in the evidence. The effects of physical and mental health on a range of socioeconomic outcomes will be explored. Mental health will receive as much focus as physical health, and social outcomes are of equal interest to economic outcomes.

By comparing the socioeconomic outcomes of individuals with varying levels of health, the research will be able to draw conclusions about the value of maintaining good health across the lifespan. To assess causality, exposure must come before the outcome that is being measured. Using longitudinal studies, which follow up cohort members at a series of points over their lives, means the timing of the exposure can be identified. The dynamic relationships between health and socioeconomic factors mean, however, that they are likely to change in parallel. Knowing the timing alone will not allow us to draw conclusions about causality. The research projects will therefore use sophisticated statistical and analytical methods to establish causality.

What will this research programme tell us?

Some of the projects will look at a broad range of health inputs and socioeconomic outputs. Others will focus in detail on key health conditions (eg childhood obesity, common mental health problems) or socioeconomic factors (eg detailed employment outcomes).

It’s possible to assess so many exposures and outcomes because of the breadth of information in the cohort studies and because of data linkage. Linking data allows the researchers to look at administrative data (eg health service use or benefit payments) alongside self-reported and biomedical data.

A summary of the six research projects, an overview table, and technical details of the innovative research methods by which they will infer causality are available as an appendix on the Health Foundation’s website.

Inferring causality

All six projects will examine the complex, multidirectional relationship between people’s health and socioeconomic factors. The overall aim is to establish the causal effects of health on social and economic outcomes, separate from the effects that those factors can have on health, and separate from the effect of confounding factors. They will use recent developments in statistical methods, data availability (notably genetic data), and the ability to link data from different sources.

Aspects of time

The projects will investigate whether there are key times of life at which people’s health is particularly important. For example, are there times when a change in health has a bigger effect, and are there cumulative effects over the lifespan?

The projects will also focus on changes in the relationship between health and socioeconomic factors over time. As the prevalence of health conditions, the ability to manage them, and the socioeconomic context change over time, the strength and nature of the relationship between them might change. For example, an increase in obesity levels might reduce stigma and negative social outcomes, and the right to request flexible working might change the effect of health on a person’s ability to work. Some of the research will look across generations (via cross-cohort comparisons and intergenerational comparisons within cohorts) to see whether the relationship between health and outcomes changes over time.

The long-term data provided by the longitudinal studies will allow research into the long-term effects of people’s health on their socioeconomic outcomes. Some of the studies contain information about three generations of the same family, enabling researchers to look at possible intergenerational effects (eg whether parental mental health affects the employment of their children).

Modifying factors

It is likely that the relationship between health and socioeconomic factors varies by individual characteristics (eg education, level of deprivation, gender, ethnicity). The cohorts used by the researchers are large enough for them to explore many such factors. This could be important in understanding health and socioeconomic inequalities and how we, as a society, could mitigate or even prevent these inequalities.

Effects on others

The longitudinal studies include data on household members and their immediate families. Exploring this data could identify ‘spill-over’ effects on others, such as the socioeconomic consequences of caring for a relative with ill health.

Limitations

This briefing has already outlined the challenges of establishing causality. Although the six research projects will use innovative methods and varied data sources to address those challenges, this is a very new area of research. Considering the findings of the research programme as a whole – exploring the consistencies and differences – will give a better understanding of the relationship between health and socioeconomic factors and increased confidence in the projects’ conclusions.

What do we plan to do with the results?

The research projects began in 2018 and will be complete by 2021. The Health Foundation will regularly bring the researchers together to discuss interim findings.

Policy implications will be at the fore throughout the course of this work. The breadth of the research programme will allow us to consider the effects of health on a wide range of outcomes, as well as the importance of viewing health as an asset across different areas of government and sectors of the economy. We anticipate that the research programme will provide robust, comprehensive evidence about the social and economic benefits of investing in health.

More information on our Social and Economic Value of Health research programme, including updates and contact details of the lead researchers from each project, can be found on our website.

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