The social determinants of health (SDOH) are the economic and social conditions and their distribution among the population that influence individual and group differences in health status. They are health promoting factors found in one’s living and working conditions (such as the distribution of income, wealth, influence, and power), rather than individual risk factors (such as behavioural risk factors or genetics) that influence the risk for a disease, or vulnerability to disease or injury. According to some viewpoints, the distributions of social determinants are shaped by public policies that reflect the influence of prevailing political ideologies of those governing a jurisdiction. The World Health Organization says, “This unequal distribution of health-damaging experiences is not in any sense a ‘natural’ phenomenon but is the result of a toxic combination of poor social policies, unfair economic arrangements [where the already well-off and healthy become even richer and the poor who are already more likely to be ill become even poorer], and bad politics.”
Commonly accepted determinants
There is no single definition of the social determinants of health, but there are commonalities, and many governmental and non-governmental organizations recognize that there are social factors which impact the health of individuals.
- The Social gradient
- Early Life
- Social exclusion
- Social support
In Canada, these social determinants of health have gained wide usage.
- Income and income distribution
- Unemployment and job security
- Employment and working conditions
- Early childhood development
- Food insecurity
- Social exclusion
- Social safety network
- Health services
- Aboriginal status
These SDOH are clearly related to health outcomes, are closely tied to public policy, and are clearly understandable by the public. They tend to cluster together – for example, those living in poverty also experience numerous other adverse social determinants. The quality and equitable distribution of these social determinants in Canada and the USA are clearly well below the standards seen in other developed nations.
The WHO later developed a Commission on Social Determinants of Health, which in 2008 published a report entitled “Closing the Gap in a Generation”. This report identified two broad areas of social determinants of health that needed to be addressed. The first area was daily living conditions, which included healthy physical environments, fair employment and decent work, social protection across the lifespan, and access to health care. The second major area was distribution of power, money, and resources, including equity in health programs, public financing of action on the social determinants, economic inequalities, resource depletion, healthy working conditions, gender equity, political empowerment, and a balance of power and prosperity of nations.
The 2011 World Conference on Social Determinants of Health brought together delegations from 125 member states and resulted in the Rio Political Declaration on Social Determinants of Health. This declaration involved an affirmation that health inequities are unacceptable, and noted that these inequities arise from the societal conditions in which people are born, grow, live, work, and age, including early childhood development, education, economic status, employment and decent work, housing environment, and effective prevention and treatment of health problems.
The United States Centers for Disease Control defines social determinants of health as “life-enhancing resources, such as food supply, housing, economic and social relationships, transportation, education, and health care, whose distribution across populations effectively determines length and quality of life”. These include access to care and resources such as food, insurance coverage, income, housing, and transportation. Social determinants of health influence health-promoting behaviours, and health equity among the population is not possible without equitable distribution of social determinants among groups.
Woolf states, “The degree to which social conditions affect health is illustrated by the association between education and mortality rates”. Reports in 2005 revealed the mortality rate was 206.3 per 100,000 for adults aged 25 to 64 years with little education beyond high school, but was twice as great (477.6 per 100,000) for those with only a high school education and 3 times as great (650.4 per 100,000) for those less educated. Based on the data collected, the social conditions such as education, income, and race were very much dependent on one another, but these social conditions also apply independent health influences.
Marmot and Bell found that in wealthy countries, income and mortality are correlated as a marker of relative position within society, and this relative position is related to social conditions that are important for health including good early childhood development, access to good quality education, rewarding work with some degree of autonomy, decent housing, and a clean and safe living environment. The social condition of autonomy, control, and empowerment turns are important influences on health and disease, and individuals who lack social participation and control over their lives are at a greater risk for heart disease and mental illness.
International health inequalities
Even in the wealthiest countries, there are economic inequalities in health between the rich and the poor. Canadian authors Labonte and Schrecker from the University of Ottawa note that globalization is a key context for the study of the social determinants of health, and as Bushra (2011) the impacts of globalization are asymmetric. As a result, there is an uneven distribution of wealth and influence both within and across national borders, leading to negative impacts on the social determinants of health. The Organization for Economic Cooperation and Development found significant differences among developed nations in health status indicators such as life expectancy, infant mortality, incidence of disease, and death from injuries. International labor migration and the policies that attempt to regulate it can also impact the health of only those that migrate but their family members who stay behind.
These inequalities may exist in the context of the health care system, or in broader social approaches. According to the WHO’s Commission on Social Determinants of Health, access to health care is essential for equitable health, and it argued that health care should be a common good rather than a market commodity. However, there is substantial variation in health care systems and coverage from country to country. The Commission also calls for government action on such things as access to clean water and safe, equitable working conditions, and it notes that dangerous working conditions exist even in some wealthy countries. In the Rio Political Declaration on Social Determinants of Health, several key areas of action were identified to address inequalities, including promotion of participatory policy-making processes, strengthening global governance and collaboration, and encouraging developed countries to reach a target of 0.7% of gross national product (GNP) for official development assistance.
The UK Black and The Health Divide reports considered two primary mechanisms for understanding the process by which the social determinants influence health: cultural/ behavioural and materialist/structuralist. The cultural/behavioural explanation was that individuals’ behavioural choices (e.g., tobacco and alcohol use, diet, physical activity, etc.) were responsible for their developing and dying from a variety of diseases. However, both the Black and Health divide reports found that behavioural choices are heavily structured by one’s material conditions of life, and these behavioural risk factors account for a relatively small proportion of variation in the incidence and death from various diseases.
The materialist/structuralist explanation emphasizes the material conditions under which people live. These conditions include availability of resources to access the amenities of life, working conditions, and quality of available food and housing among others. Within this view, three frameworks have been developed to explain how social determinants influence health. These frameworks are: (a) materialist; (b) neo-materialist; and (c) psychosocial comparison. The materialist explanation is about how living conditions – and the social determinants of health that constitute these living conditions – shape health. The neo-materialist explanation extends the materialist analysis by asking how these living conditions come about. The psychosocial comparison explanation considers whether people compare themselves to others and how these comparisons affect health and wellbeing.
The wealth of nations is a strong indicator of population health. But within nations, socio-economic position is a powerful predictor of health as it is an indicator of material advantage or disadvantage over the lifespan. Material conditions of life determine health by influencing the quality of individual development, family life and interaction, and community environments. Material conditions of life lead to differing likelihood of physical (infections, malnutrition, chronic disease, and injuries), developmental (delayed or impaired cognitive, personality, and social development), educational (learning disabilities, poor learning, early school leaving), and social (socialization, preparation for work, and family life) problems. Overall wealth of nations is a strong indicator of population health. But within nations, socio-economic position is a powerful predictor of health as it is an indicator of material advantage or disadvantage over the lifespan. Material conditions of life also lead to differences in psychosocial stress. The fight-or-flight reaction – chronically elicited in response to threats such as income, housing, and food insecurity, among others – weakens the immune system, leads to increased insulin resistance, greater incidence of lipid and clotting disorders, and other biomedical insults that are precursors to adult disease.
Adoption of health-threatening behaviours is also influenced by material deprivation and stress. Environments influence whether individuals take up tobacco, use alcohol, experience poor diets, and have low levels of physical activity. Tobacco and excessive alcohol use, and carbohydrate-dense diets are also means of coping with difficult circumstances. The materialist approach offers insight into the sources of health inequalities among individuals and nations and the role played by the social determinants of health.
The neo-materialist approach is concerned with how nations, regions, and cities differ on how economic and other resources are distributed among the population.This distribution of resources can vary widely from country to country. The neo-materialist view therefore, directs attention to both the effects of living conditions – the social determinants of health – on individuals’ health and the societal factors that determine the quality of the distribution of these social determinants of health. How a society decides to distribute resources among citizens is especially important.
The social comparison approach holds that the social determinants of health play their role through citizens’ interpretations of their standings in the social hierarchy.There are two mechanisms by which this occurs. At the individual level, the perception and experience of one’s status in unequal societies lead to stress and poor health. Feelings of shame, worthlessness, and envy can lead to harmful effects upon neuro-endocrine, autonomic and metabolic, and immune systems.Comparisons to those of a higher social class can also lead to attempts to alleviate such feelings by overspending, taking on additional employment that threaten health, and adopting health-threatening coping behaviours such as overeating and using alcohol and tobacco. At the communal level, widening and strengthening of hierarchy weakens social cohesion, which is a determinant of health. The social comparison approach directs attention to the psychosocial effects of public policies that weaken the social determinants of health. However, these effects may be secondary to how societies distribute material resources and provide security to its citizens, which are described in the materialist and neo-materialist approaches.
Life-course approaches emphasize the accumulated effects of experience across the life span in understanding the maintenance of health and the onset of disease. The economic and social conditions – the social determinants of health – under which individuals live their lives have a cumulative effect upon the probability of developing any number of diseases, including heart disease and stroke  Studies into the childhood and adulthood antecedents of adult-onset diabetes show that adverse economic and social conditions across the life span predispose individuals to this disorder.
Hertzman outlines three health effects that have relevance for a life-course perspective. Latent effects are biological or developmental early life experiences that influence health later in life. Low birth weight, for instance, is a reliable predictor of incidence of cardiovascular disease and adult-onset diabetes in later life. Experience of nutritional deprivation during childhood has lasting health effects.
Pathway effects are experiences that set individuals onto trajectories that influence health, well-being, and competence over the life course. As one example, children who enter school with delayed vocabulary are set upon a path that leads to lower educational expectations, poor employment prospects, and greater likelihood of illness and disease across the lifespan. Deprivation associated with poor-quality neighbourhoods, schools, and housing sets children off on paths that are not conducive to health and well-being.
Cumulative effects are the accumulation of advantage or disadvantage over time that manifests itself in poor health. These involve the combination of latent and pathways effects. Adopting a life-course perspective directs attention to how social determinants of health operate at every level of development – early childhood, childhood, adolescence, and adulthood – to both immediately influence health and provide the basis for health or illness later in life.
Chronic stress and health
Stress is hypothesised to be a major influence in the social determinants of health. There is a relationship between experience of chronic stress and negative health outcomes. There are two ways that this relationship is explained, through both direct and indirect effects of chronic stress on health outcomes.
One possible reason for the relationship between chronic stress and health outcomes is the effect that stress has on the physiology of a person. This is referred to as a direct relationship between chronic stress and health. The long term stress hormone, cortisol, is believed to be the key driver in this relationship. Chronic stress has been found to be significantly associated with chronic low grade inflammation, slower wound healing, increased susceptibility to infections, and poorer responses to vaccines. For example, a study of otherwise healthy adult males found that those with high levels of perceived stress in their lives had significantly longer wound healing times, and that elevated cortisol levels, rather than health behaviour responses, appeared to be the main reason for this relationship. Meta-analysis of healing studies has found that there is a robust relationship between elevated stress levels and slower healing for many different acute and chronic conditionsHowever, it is also important to note that certain factors, such as coping styles and social support, can mitigate the relationship between chronic stress and health outcomes.
Stress can also be seen to have an indirect effect on health status. One way this happens is due to the strain on the psychological resources of the stressed individual. Chronic stress is common in those of a low socio-economic status, who are having to balance worries about financial security, how they will feed their families, housing status, and many other concerns. Therefore, individuals with these kinds of worries may lack the emotional resources to adopt positive health behaviours. Chronically stressed individuals may therefore be less likely to be able to prioritise their health.
In addition to this, the way that an individual responds to stress can influence their health status. Often, individuals responding to chronic stress will develop coping behaviours, some of which have a positive influences on health and others which have a negative influence. People who cope with stress through positive behaviours such as exercise or social connections may not be as affected by the relationship between stress and health, whereas those with a coping style more prone to over consumption (i.e. emotional eating, drinking, smoking or drug use) are more likely to be see negative health effects of stress. For example, a laboratory study has shown that, while stress did not alter calorie intake or food type eaten when averaged across the sample as a whole, when looking at a subset of the sample who were classed as emotional eaters, high stress levels were associated with eating more high fat and sweet food and a more calorie dense meal overall. Therefore, the authors conclude that stress may compromise the health of certain susceptible individuals (I.e those with an emotional eating coping style).
The detrimental effects of stress on health outcomes are hypothesised to partly explain why countries that have high levels of income inequality have poorer health outcomes compared to more equal countries. Wilkinson and Picket hypothesise in their book The Spirit Level that the stressors associated with low social status are amplified in societies where others are clearly far better off.