New Horizons in Modeling and Simulation for Social Epidemiology and Public Health. Daniel Kim
a role in declines in life expectancy among Americans for a second consecutive year in 2015 and 2016 (Kochanek et al. 2017), marking the first time this has happened in more than half a century. Gun deaths also rose in 2016 for a second consecutive year. Firearm‐related injuries contribute substantially to life expectancy, accounting for 7.1% of premature deaths or years of potential life lost before the age of 65 (Fowler et al. 2015).
Americans reach the age of 50 in worse health than their counterparts in other high‐income countries as older adults experience higher levels of morbidity and mortality from chronic diseases. Even socioeconomically advantaged (i.e. college educated or higher income) Americans fare worse than their counterparts in England and other countries (National Research Council and Committee on Population 2013). In offering potential explanations for these patterns, the panel referenced underlying societal factors—which we now commonly refer to as the social determinants of health—as possible root causes of the higher levels of morbidity and mortality and shorter life expectancies in the United States (National Research Council and Committee on Population 2013). For instance, despite its vast economy, the United States possesses considerably higher poverty rates and levels of income inequality than most high‐income countries. In addition, although the United States once led the world in educational performance, students in many other countries now routinely outperform US students; these findings are analogous to the relative standings of these countries in the Health Olympics. Finally, in contrast to the United States, a number of other countries such as Sweden and Norway in Scandinavia offer larger public welfare and other social safety net programs. Such programs and services could conceivably help residents to better weather the storm of adverse effects on health caused by poor economic and social conditions (Adema et al. 2011; Kim 2016).
1.3 What are the Social Determinants of Health?
In 2005, the World Health Organization (WHO) established a Commission on the Social Determinants of Health that was tasked with the job of supporting countries to address the upstream social factors that shape population health and health inequities (WHO Commission on the Social Determinants of Health 2008). The overall goal of the Commission was to draw the attention of governments and society to the social determinants of health and to create better social conditions for health, particularly amongst the most vulnerable populations. The commission delivered its final report to the WHO in 2008 (WHO Commission on the Social Determinants of Health 2008).
As defined by the WHO Commission, the social determinants of health are “the conditions in which people are born, grow, live, work, and age” (WHO Commission on the Social Determinants of Health 2008). These social determinants extend well beyond the confines of the health care system and include aspects of our neighborhood and workplace environments (e.g. the food, built, and social environments) and the social and economic policies (e.g. tax policies) that govern the regions in which we live. It is these “upstream” nonmedical social determinants that are increasingly understood as the root causes of population health inequalities, even within rich nations (Marmot and Bell 2009; Woolf and Braveman 2011). Such social determinants offer a critical lens to explain why the average life expectancy in America has lagged well behind other nations, despite the fact that the United States remains one of the richest nations in the world and spends more on a per‐capita basis on health care than all other developed nations globally (Marmot and Bell 2009). Identifying what impacts various social determinants have on population health is now the central focus of the growing public health field known as social epidemiology.
The WHO Commission on the Social Determinants of Health developed a conceptual framework of the social determinants of health (Solar and Irwin 2007; WHO Commission on the Social Determinants of Health 2008). Figure 1.2 shows an adaptation of this conceptual framework. As illustrated in this figure, the social determinants of health are composed of the material living and working conditions and social environmental conditions in which people are born, live, work, and age, along with the structural drivers of these conditions. These structural drivers include individual‐ and area‐level socioeconomic status (SES), race/ethnicity, residential segregation, gender, social capital/cohesion, and the macroeconomic and macrosocial contexts, e.g. macroeconomic and social policies including labor market regulations (Muntaner et al. 2012), political factors including governance and political rights (Chung and Muntaner 2006; Bezo et al. 2012), and cultural factors. Examples of macroeconomic determinants include the gross domestic product (GDP) per capita and income inequality—the gap between the rich and the poor within societies.
Figure 1.2 A social determinants of health conceptual framework.
Source: Adapted from Kim and Saada (2013) and Solar and Irwin (2007).
The broader macroeconomic and social context generates social stratification, that is, the sorting of people into dominant and subordinate SES, racial/ethnic, and gender groups (Figure 1.2). Through social stratification and differential exposures of individuals to levels of material factors/social resources, social determinants such as individual/area‐level SES, race/ethnicity, and social capital shape individual‐level intermediary determinants, including behavioral factors (e.g. maternal smoking), biological factors, and psychosocial factors (e.g. social support), which in turn produce differential risks of, and inequities in, health outcomes (Figure 1.2). Access to health care and the quality of health care are also determinants of these outcomes, yet health care factors are believed to play lesser roles compared to societal factors (Figure 1.2). This is supported by cross‐national evidence on health care spending and life expectancy. Moreover, even in societies with a national health system in place (e.g. Canada and the United Kingdom), socioeconomic disparities and gradients in health are salient and well established.
1.4 The 3 P's (people, places, and policies) Population Health Triad
Implicit in this conceptualization of the social determinants of health is that more upstream population characteristics, places, and policies matter to population health. Jointly, we can refer to these three factors that are pivotal to population health as the “3 P's” (people, places, and policies) Population Health Triad (Figure 1.3). The classic Host–Agent–Environment epidemiologic triad posits that a susceptible host, an external agent, and an environment are needed to produce disease. Similarly, both places and policies interact with populations to manifest disease. For example, neighborhoods where we live can influence our health through physical and material characteristics such as air quality, access to nutritious foods and opportunities for leisure and exercise, health services, and education/schools and employment opportunities (Braveman et al. 2011). Policies in nonhealth sectors (e.g. transportation, education, and housing) can also intersect with and shape health. Social policies such as those that affect levels of welfare spending and tax policies that determine the rich–poor gap have plausible linkages to the social environment, health behaviors, and individual health and disease endpoints. Reciprocal interactions are also possible, with populations being able to shape both policies and places, such as by mobilizing together through social capital (e.g. political activism) to effect change (Figure 1.2).
Figure 1.3 The 3 P's (people, places, and policies) Population Health Triad.
To