Communicating the SDOH as a list of influential factors.

The list approach to organizing and communicating the SDOH has benefits and challenges. One benefit is that lists present information about the SDOH in organized ways that highlight important features to readers. This may facilitate dissemination and widespread understanding, where listed points are clear, concise, and easily reproducible (e.g., make a photocopy to share with colleagues). A challenge of communicating the SDOH in lists, however, is that lists are not exhaustive, as authors must choose what information is included. Additionally, lists may lead to confusion where many versions exist on the same topic (see, for example, Raphael’s [2006] article which compares Canadian SDOH lists).[99] Some lists attempt to be as comprehensive as possible within the scope of their work, for example by compiling a glossary to accompany listed terms,[74] while others prioritize certain SDOH over others for different audiences or topics of interest.[34, 75, 81] Additionally, authors do not always state their intentions in compiling SDOH lists, which may have implications for how their lists are interpreted. Some lists, for example, may be purposefully organized to list the highest priority SDOH first, while others may be less intentionally compiled (e.g., alphabetical order). Important information may be buried in this case, should readers uncritically skim lists from top to bottom. Alternatively, readers may assign greater importance to the listed elements they read first. To some extent, the above challenges could be addressed if a single list was adopted by authors. Raphael’s list SDOH represents one example that has been widely adopted by Canadian authors.[34]

The list approach also presents a potential challenge for communicating the complexity of the SDOH. The SDOH represent much more than a list can convey, such as issues related to how listed SDOH intersect with one another, the social and historical nature of SDOH, or the foundational role of equity. With lists, there is also the drawback of being too inclusive or providing too much breadth to be of practical use. An overly inclusive list does not provide direction, and may direct focus to issues that are at the periphery of the SDOH, perhaps because they are or seem to be the easiest to address. However, lists do serve the needs of many authors, especially those who wish to briefly communicate pertinent elements of the SDOH to their audience. This may be especially true among grey literature publications, for example where SDOH resources are produced to inform practitioners. Academics, on the other hand, may publish as an opportunity to theoretically interrogate or expand upon the SDOH, taking a more narrative approach.

As indicated by its name, the list approach to the SDOH provides a list of factors that influence health. The British Columbia Government, for example, in their 2008 discussion paper on health inequities in the province provides readers with two lists of the SDOH–one noting upstream influences (i.e., macroeconomic policies; culture, ethnicity and values; governance; income and social status; employment and working conditions; education and literacy; and, early childhood development) and the other downstream determinants (i.e., physical built environments; social support networks; social environments; access to effective health care services; risk behaviours; personal health practices and coping skills; gender; and, biological and genetic endowment).[65] The elements of these lists appear to have been purposively chosen to expand to the discussion of policy options for action on the SDOH among a wide range of audiences (e.g., health professionals, decision makers). We discuss the notions of upstream and downstream interventions in detail later.

Communicating the SDOH through conceptual models.

The model, or conceptual framework, approach moves beyond a list of SDOH to show (often visually) how various elements interconnect and are experienced at different levels (e.g., societal, community, family, individual) to produce different outcomes (e.g., opportunities, health outcomes, distribution of opportunities). Most models share the idea that health represents a web of social influences.[103] Well-known examples of SDOH models, presented in chronological order, include Evans and Stoddart’s (1990) framework, which shows how individual and social factors interact outside of the health care system,[22] Whitehead and Dahlgren’s (1991) ‘rainbow model’ which shows concentric half-circles of influential social factors,[104] and more recently, Solar and Irwin’s (2007) conceptual model produced for the WHO that shows the multiple directions through which structural and intermediary determinants impact health and health equity.[16] Lesser known examples include Fox and Meier’s (2009) right to development SDOH model [21] and the model for Métis SDOH that shows interrelationships specific to this population (e.g., self-determination, land, colonization).[66] While numerous other models exist, they have been documented elsewhere [e.g., [20, 89, 93, 103, 105–106]] and will not be reviewed here. A comprehensive and illustrative guide to various models of the SDOH, including those outside the scope of this review, is provided in MacDowell’s webpage created for medical students at the University of Ottawa in Canada.[107]

The model approach also brings potential challenges and benefits to communicating the SDOH. They are particularly beneficial in that they depict the influence of social, economic, and political factors at multiple levels. Some models even identify areas where action on the SDOH can be taken.[15, 108] Others serve to illustrate pathways, which are helpful to individuals in understanding the ‘how’ behind the SDOH. One of the challenges is that they may oversimplify (and thus misrepresent) or overcomplicate (and thus overwhelm) the SDOH. To the extent that models and lists do not resonate with members of the public, for any reason, they may not instill a sense of need or urgency to act (e.g., contact their elected representative on SDOH-related matters), to the detriment of public engagement in public policy decision-making.

Communicating the SDOH through stories or narratives.

The story, or narrative, approach to communicating the SDOH provides a way to convey feelings or experiences that simply is not possible in lists and models. A well-known example is the Public Health Agency of Canada’s narrative that asks the question, “Why is Jason in the hospital?”[109] The story goes on to answer increasingly structural questions about why Jason was in the hospital, had an infection, played in the junk yard, et cetera. Each answer reveals a wider set of social influences on Jason’s health. While the story approach did present itself in our review, it was not common. This is likely an artifact of our review methods, which did not include searching specifically for sources aimed at members of the public.

The story approach may fill the emotive void left by list and model approaches, to make the SDOH compelling to audiences. When reading an SDOH narrative, readers may experience feelings relating to luck, privilege, or fairness, and in some cases may even be compelled to act.[110] The story approach may lack the structure required to gain credibility in policy decisions when used on its own, though it may be more effective when used in combination with lists or models in its ability to convey complex information in understandable ways. A good illustration of this combined approach comes from the WHO CSDH final report, which includes a list (three overarching recommendations for action: [1] improve the conditions of daily life; [2] tackle the inequitable distribution of power, money and resources; and [3] measure and understand the problem and assess the impact of action [17]]; a conceptual framework, or model, of the SDOH, which allows readers to visualize how certain factors work together to influence health; and a story: the report itself is written in a way that crafts a compelling narrative, such as its use of case examples and personalization (e.g., “Social injustice is killing people on a grand scale.”[17]).

Epistemological differences in presenting the SDOH.

The different ways of presenting the SDOH may align with the different epistemologies that underlie the literature. Ashcroft (2010) identifies objectivism, constructionism, and subjectivism as epistemologies present within the SDOH paradigm.[80] Objectivism was predominantly visible in articles that used statistical methods to explore and quantify the relationship between health and SDOH, where knowledge was produced in the context of epidemiology and population health.[80] Some examples include Regidor’s (2006) review of methods measuring socioeconomic position [24] and Gustafsson et al.’s (2014) quantitative analysis of the life-course accumulation of neighbourhood disadvantage and allostatic load.[79] There were also examples of a constructivist paradigm apparent in this review, where articles sought to present an understanding of the SDOH based on knowledge they had collected from the experiences of others. In their interviews with Medical Officers of Health and public health unit staff, Raphael, Brassolotto, and Baldeo (2014), for example, showed how public health professionals perceived the SDOH and how their role in acting on them differed, depending on whether or not their public health unit supported activities beyond traditional public health services or programs (e.g., vaccination, health education), such as advocacy on issues like hunger or poverty, or raising public awareness of the SDOH.[30] Finally, examples of subjectivism from this review are apparent in the articles that incorporated Aboriginal understandings and experiences of SDOH, through recognition of important influential factors such as the dispossession of land, cultural resilience, self-determination, and legacy of residential schools.[18, 66, 84, 108, 111–113]

We did not explore the literature with the explicit intent of discerning epistemologies, which limits our ability to comment on the extent to which different ones were used. However, in considering our sample at face value one thought is that academic authors may adopt more objectivist or constructivist epistemologies compared to non-academics, perhaps drawing on or developing their own conceptual models or frameworks to present their findings. This seems likely considering that non-academic authors may wish to convey the SDOH in ways more relatable and easily understood by a general audience or the public, and therefore may adopt more constructivist or subjectivist epistemologies through using lists and narratives.

Health equity as a binding concept for the SDOH.

The concept of health equity, which refers to a socially just state wherein all members of a population have access to the best available opportunities for health,[56] frequently appeared as an essential element in the SDOH. Health inequity, accordingly, refers to unfair and avoidable differences in health between population groups that reflect inequitable access to those opportunities.[17] Health equity and inequity are considered the socially produced results of systematic societal processes that contribute to distribution of resources.[114]

In the literature reviewed here, health equity was predominantly used when discussing the structural or societal-level changes needed to improve health. Studies also referred to health equity when making ethical claims (e.g., health equity as a normative concept, where a fair society is explicitly valued),[16] when discussing approaches to intervene on the SDOH (e.g., taking a targeted approach to intervention, that focuses on those living in disadvantaged circumstances),[115] and when discussing causes of ill health between social groups.[67]

Quantitative content analysis of all sources revealed the frequency of use of the above terms. Equity terms (equity, inequity, inequities) were used in 77.8% of articles (n = 84). These terms were employed most frequently in WHO-related documents; namely, the WHO CSDH final report and documents that referenced this report. Other papers that frequently used the term health equity included a sociological commentary on health equity,[69] an Alberta Health Services publication on social environments and health,[93] and a paper produced by a private organization regarding the SDOH agenda in Canada.[116] Terms related to equality (equality, inequality, inequalities) were used in 79.6% of articles (n = 86). Equality terms were used most frequently in two articles by Graham, in her writings on the SDOH in the context of UK government policy.[61, 103] Others included a research article comparing welfare state regimes,[33] and a commentary reviewing key tenets of the WHO CSDH.[117] The frequency of use for these terms is further broken down in Table 2.

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Table 2. Counts of key terms used in the SDOH literature.

https://doi.org/10.1371/journal.pone.0177306.t002

Related to health equity and inequity are the terms equality and inequality. Equality and inequality also refer to differences in health as present or absent, but do not carry the same moral undertones as equity and inequity.[114] They allow health differences to be acknowledged and discussed without necessarily adopting ethical or normative claims about what is fair and avoidable. As shown in Table 2, the terms (in)equity and (in)equality appeared with similar frequency. This may simply reflect that the terms are used interchangeably.[103] Alternatively, (in)equality may be intentionally employed to avoid the implications associated with the reasons for differences in health, from an SDOH point of view. Such strategic use of terms may be especially true for studies published by authors within organizations where there may be real or perceived consequences of associating SDOH-related differences as unfair (i.e., bearing political critique).[27] Finally, the use of (in)equity over (in)equality and vice versa may reflect differences in how understandings of the SDOH are conceptualized and how they operationalize different means of action (e.g., policy change, targeted health services). We expand on this third reason below.

The social gradient in health: A key concept of the SDOH.

Another key concept we observed as prominent in the literature reviewed is the social gradient in health, which refers to the stepwise relationship between health and social position.[81, 118] According to the social gradient, which “runs right across society” health status is influenced by an individual’s position in the social hierarchy, which itself is influenced by social, political, and economic circumstances.[81, 118]

The social gradient in health appeared in various forms in the literature that we reviewed. For example, some articles attempted to quantify the social gradient (e.g., by measuring the relationship of occupational class and health).[81] Other articles included discussion on the chances individuals had to achieve good health.[111] Finally, some articles contained content that aligned strongly with the concept of the social gradient in health but using different language–a good example is the theory of fundamental causes (i.e., that the association between health and social status endures due to the access one has to fundamental, health protecting resources such as money, knowledge, and power).[95]

To further interrogate the use of the social gradient in health in the literature, we conducted a quantitative content analysis of the social gradient in health and related terms. As shown in Table 2, ‘social gradient’ was used in 37% of our articles (n = 40); ‘social hierarchy’ was used in 29.6% of articles (n = 32); ‘social position’ was used in 56.5% (n = 61); and, ‘social ladder’ was used in 9.3% (n = 10). These findings suggest the wide use of this concept.

Upstream action on the SDOH.

Much of the literature that we reviewed supported an upstream approach to health equity by reducing gradients and promoting healthy macro-level policies. A major emphasis among articles supporting a gradient approach was the recognition that a collaborative and integrative approach would be necessary. Some articles called for greater collaboration between disciplines, departments, or sectors (e.g., academic disciplines, government departments, public/private).[15, 17, 22, 26, 64, 75, 89, 93, 116, 123–124] Others encouraged a ‘whole-of-society’ approach where citizens would mobilize themselves to bring change to societal conditions in ways that facilitate health equity, at times transcending the health sector to areas such as education, social welfare, food and drug administration, et cetera.[17, 20, 26, 71, 78, 87, 96, 116]

A good illustration of the gradient and a healthy macro-policy approach to acting on the SDOH is Brennenstuhl et al.’s (2012) systematic review of welfare regimes and population health inequalities.[125] The authors found that a social democratic approach to governance, whereby social and economic interventions that support equality are implemented within a capitalist framework, with policies such as generous pensions, fostered population health and health equity (e.g., lower infant mortality rate).[125] It is important to note that empirical evaluative research on this social democratic approach to governance is limited.

While upstream, gradient, and healthy macro-social policy approaches seem desirable for their ability to address the root causes of health inequities and act on multiple SDOH across sectors,[17] they have also been subject to criticism. Popay et al. (1998), for instance, reviews three critiques of quantitative research on inequalities in health: (1) they may lack explanatory power in linking agency and structure relating to health inequalities, in the context of social structures, (2) macrosocial frameworks may fail to address complexities in explaining the causes of health inequalities, and, (3) the notion of place, as defined in macrosocial explanatory models, has not been conceptualized in its social and historical contexts (e.g., class, living place, gender, age, et cetera).[126] The critical population health research perspective, which “requires asking more critical questions about the social and economic causes and consequences of health inequalities…”[127] appears to have been one response these critiques that has gained momentum in recent research on SDOH (e.g., Richmond and Ross 2009; Labonté, Polanyi, Muhajarine, et al. 2005).[2, 18]

Action on the SDOH further downstream.

In other articles, action on the SDOH was understood with reference to specific subgroups facing social disadvantage. This approach to ‘tackling health inequalities’) can be considered more ‘downstream.’[103] That is, rather than addressing the wider structural (i.e., social, political, economic) influences that shape the distribution of health determinants, this approach focused more on meeting the immediate needs of individuals adversely affected by health inequality, such as by increasing access to services.[103] This conceptualization aligns with the ‘remedying health disadvantages’ approach presented in Graham’s (2004) typology of tackling health inequalities.[120] and to approaches that, according to Whitehead (2007), involve attempts to strengthen individuals (category 1) or communities (category 2) characterized by socio-economic disadvantage, for example by developing the life skills of or building social cohesion in these communities.[121] As Graham (2004) notes, one drawback of a remedying health disadvantages approach is that it may narrow the scope of potential policy solutions to those that focus on individuals experiencing social disadvantage (i.e., a targeted approach), which may be less effective if action on broader determinants that create social disadvantage is not considered.[120] Furthermore, intervention approaches that are confined to sub-groups (i.e., ‘those at the bottom’), may bring negative effects to other groups, such as the potential stigmatization that may occur when publicly identifying a vulnerable group for the purpose of intervention.[120]

In some cases, as noted by Frohlich et al. (2006), an approach focusing on disadvantaged sub-populations is necessary where certain groups may require special attention at the community level so not to be adversely affected by certain policies.[112, 128] As some authors, including Graham, have acknowledged, there is a strong moral basis for tackling health inequalities at this level (especially in wealthy nations) so that those at the bottom are not denied of their basic needs or the average standard of living enjoyed by the majority of the population.[120] In certain circumstances (e.g., where people experience ill health or disability as the result of social, political, and economic inequalities), it may be necessary to focus on improving the health of those most disadvantaged so they do not fall further behind the rest of the population. The notion of proportionate universalism has been put forth to recognize the challenges posed by population-level interventions for certain groups.[129–131] The idea behind proportionate universalism, as stated in Fair Society, Healthy Lives: The Marmot Review, is, “To reduce the steepness of the social gradient in health, actions must be universal, but with a scale and intensity that is proportionate to the level of disadvantage.”[129]

While proportionate universalism was not prominent in our target literature (which makes sense considering its recency), we found that targeted and downstream approaches to health equity and the SDOH were prevalent in the literature. In many cases this reflected the professional scope of the authors. The Canadian Nurses Association, for example, put forth an idea for how individual nursing practice could act on the SDOH, by asking patients certain questions (e.g., their circumstances relating to income or housing), considering whether patients have access to health resources or recommended medical treatments, or knowing available community resources that could assist their clients.[91] Other articles spoke of physicians’ “ethical duty to their patients” to act on the SDOH,[92] or the need for physicians to “be the natural attorneys of the disadvantaged.”[75]

A similar trend towards targeted and downstream approaches to action on the SDOH was found in literature reporting on the public health workforce McIntyre et al.’s (2013) focus group with individuals who were affiliated with Canadian public health, for example, found that many participants were too preoccupied with behavioural and lifestyle approaches (e.g., diet, exercise), to attempt action at broader levels that may tackle wider spheres of influence on the determinants of health (e.g., neighbourhood, environment).[132] This may in part reflect challenges identified by Raphael et al. (2014) in their work with public health units, where participants identified that they “act where [they] think that there’s some prospect of actually changing something”; namely, through the provision of downstream services and programs.[29] In a related paper by Raphael’s group, Brassolotto et al. (2014) found that public health practitioners predominantly considered the SDOH as things to be mindful of in practice but that occurred outside the scope of their work.[27, 30] One participant stated that, “It may be emotionally satisfying to think that we can go out and restructure Canadian society. It’s self-indulgent, in my opinion, and it’s not the business we’re in.”[27] Finally, in a paper contemplating how social theory could be integrated into public health practice Potvin et al. (2005) found that public health practitioners in Canada faced difficulties acting on the SDOH because of the bureaucratic nature of their practice and its lack of instruments to implement innovative practices.[133]

An emphasis on downstream approaches to remedying health inequities may also apparent in academic scholarship. Raphael and Bryant (2015) have asserted that, aside from a handful of critical scholars, academics predominantly do not write about action on the SDOH in ways that focus on upstream, macrosocial factors in their research.[134] Unlike the public health practitioners who face potential consequences in their place of employment, however, these authors state that “the academics don’t have that excuse […] especially the tenured ones.”[134]

In summary, in the literature reviewed we identified that though health equity is a common, binding concept in the SDOH, there are different ways in its conceptualization. These differences have implications for approaches to action, which range from a more upstream, structural approach that considers the social gradient as well as the determinants and processes that distribute resources across the population, to a more downstream, community or individual-level approach that focuses on social or behavioural factors operating within specific groups (sometimes, but importantly not always, these social and behavioral factors are considered discretely or in isolation). The different approaches do not appear to have been strongly reconciled.