Advancing the Social Epidemiology Mission of the American Journal of Epidemiology.

Social epidemiology is concerned with how social forces influence population health. Rather than focusing on a single disease (as in cancer or cardiovascular epidemiology) or a single type of exposure (e.g., nutritional epidemiology), social epidemiology encompasses all the social and economic determinants of health, both historical and contemporary. These include features of social and physical environments, the network of relationships in a society, and the institutions, politics, policies, norms and cultures that shape all of these forces. This commentary presents the perspective of several editors at the Journal with expertise in social epidemiology. We articulate our thinking to encourage submissions to the Journal that: 1) expand knowledge of emerging and underresearched social determinants of population health; 2) advance new empirical evidence on the determinants of health inequities and solutions to advance health equity; 3) generate evidence to inform the translation of research on social determinants of health into public health impact; 4) contribute to innovation in methods to improve the rigor and relevance of social epidemiology; and 5) encourage critical self-reflection on the direction, challenges, successes, and failures of the field.

Socioeconomic disparities in smoking are partially explained by chronic financial stress: marginal structural model of older US adults.

BACKGROUND: A persistent socioeconomic gradient in smoking has been observed in a variety of populations. While stress is hypothesised to play a mediating role, the extent of this mediation is unclear. We used marginal structural models (MSMs) to estimate the proportion of the effect of socioeconomic status (SES) on smoking, which can be explained by an indicator of stress related to SES, experiences of chronic financial stress. METHODS: Using the Health and Retirement Study (waves 7-12, 2004-2014), a survey of older adults in the USA, we analysed a total sample of 15 260 people. A latent variable corresponding to adult SES was created using several indicators of socioeconomic position (wealth, income, education, occupation and labour force status). The main analysis was adjusted for other factors that influence the pathway from adult SES to stress and smoking, including personal coping resources, health-related factors, early-life SES indicators and other demographic variables to estimate the proportion of the effect explained by these pathways. RESULTS: Compared with those in the top SES quartile, those in the bottom quartile were more than four times as likely to be current smokers (rate ratio 4.37, 95% CI 3.35 to 5.68). The estimate for the MSM attenuated the effect size to 3.34 (95% CI 2.47 to 4.52). Chronic financial stress explained 30.4% of the association between adult SES and current smoking (95% CI 13 to 48). CONCLUSION: While chronic financial stress accounts for part of the socioeconomic gradient in smoking, much remains unexplained.

Government social assistance programmes are failing to protect the health of low-income populations: evidence from the USA and Canada (2003-2014).

BACKGROUND: Social policies that improve the availability and distribution of key socioeconomic resources such as income, wealth and employment are believed to present the most promising avenue for reducing health inequalities. The present study aims to estimate the effect of social assistance recipiency on the health of low-income earners in the USA and Canada. METHODS: Drawing on nationally representative survey data (National Health Interview Survey and the Canadian Community Health Survey), we employed propensity score matching to match recipients of social assistance to comparable sets of non-recipient 'controls'. Using a variety of matching algorithms, we estimated the treatment effect of social assistance recipiency on self-rated health, chronic conditions, hypertension, obesity, smoking, binge drinking and physical inactivity. RESULTS: After accounting for underlying differences in the demographic and socioeconomic characteristics of recipients and non-recipients, we found that social assistance recipiency was associated with worse health status or, at best, the absence of a clear health advantage. This finding was consistent across several different matching strategies and a diverse range of health outcomes. CONCLUSIONS: From a public health perspective, our findings suggest that interventions are warranted to improve the scope and generosity of existing social assistance programmes. This may include reversing welfare reforms implemented over the past several decades, increasing benefit levels and untethering benefit recipiency from stringent work conditionalities.

Canadian report card on health equity across the life-course: Analysis of time trends and cross-national comparisons with the United Kingdom.

Addressing social determinants of health (SDoH) has been acknowledged as an essential objective for the promotion of both population health and health equity. Extant literature has identified seven potential areas of investment to address SDoH: investments in sexual and reproductive health and family planning, early learning and child care, education, universal health care, as well as investments to reduce child poverty, ensure sustainable economic development, and control health hazards. The aim of this paper is to produce a 'report card' on Canada's success in reducing socioeconomic and health inequities pertaining to these seven policy domains, and to assess how Canadian trends compare to those in the United Kingdom (UK), a country with a similar health and welfare system. Summarising evidence from published studies and national statistics, we found that Canada's best successes were in reducing socioeconomic inequalities in early learning and child care and reproductive health-specifically in improving equity in maternal employment and infant mortality. Comparative data suggest that Canada's outcomes in the latter areas were like those in the UK. In contrast, Canada's least promising equity outcomes were in relation to health hazard control (specifically, tobacco) and child poverty. Though Canada and the UK observed similar inequities in smoking, Canada's slow upward trend in child poverty prevalence is distinct from the UK's small but steady reduction of child poverty. This divergence from the UK's trends indicates that alternative investment types and levels may be needed in Canada to achieve similar outcomes to those in the UK.

Illustrating a "consequential" shift in the study of health inequalities: a decomposition of racial differences in the distribution of body mass.

PURPOSE: We present a conceptual introduction to "distributional inequalities"-differences in distributions of risk factors or other outcomes between social groups-as a consequential shift for research on health inequalities. We also review a companion analytical methodology, "distributional decomposition", which can assess the population characteristics that explain distributional inequalities. METHODS: Using the 1999-2012 U.S. National Health and Nutrition Examination Survey, we apply statistical decomposition to (a) document gender-specific, black-white inequalities in the distribution of body mass index (BMI) and, (b) assess the extent to which demographic (age), socioeconomic (family income, education), and behavioral predictors (caloric intake, physical activity, smoking, alcohol consumption) are associated with broader distributional inequalities in BMI. RESULTS: Black people demonstrate favorable or no different caloric intake, smoking, or alcohol consumption than whites, but worse levels of physical activity. Racial inequalities extend beyond the obesity threshold to the broader BMI distribution. Demographic, socioeconomic, and behavioral characteristics jointly explain more of the distributional inequality among men than women. CONCLUSIONS: Black-white distributional inequalities are present both among men and women, although the mechanisms may differ by gender. The notion of "distributional inequalities" offers an additional purchase for studying social inequalities in health.

Associations between race, discrimination and risk for chronic disease in a population-based sample from Canada.

A major epidemiological finding emerging from studies using U.S. samples is that racial differences in experiences of discrimination are associated with racial differences in health. A newer area of research is exploring the population-level dynamics between race, discrimination, and health status in various societies. The objective of this study is to assess for the first time in a national sample from Canada: (a) racial differences in experiences of discrimination and, (b) the association between discrimination and chronic conditions and their major risk factors. Data were obtained from the 2013 Canadian Community Health Survey (n = 16,836). Race was categorized as Aboriginal, Asian, Black, or White. Discrimination was measured using the Williams Everyday Discrimination Scale. Outcomes included having any chronic condition or major risk factors (obesity, hypertension, smoking, binge drinking, infrequent physical activity, and poor self-rated health). Crude and adjusted (for age, sex, immigrant status, socioeconomics) logistic regressions modeled the association between (a) race and discrimination and, (b) discrimination and each outcome. Results indicated that Blacks were most likely to experience discrimination, followed by Aboriginals. For example, Blacks were almost twice as likely (OR: 1.92, 95% CI: 1.19-3.11), and Aboriginals 75 percent more likely (OR: 1.75, 95% CI: 1.37-2.22) to report being treated with less courtesy or respect than others. Blacks were more than four times as likely (OR: 4.27, 95% CI: 2.23-8.19), and Aboriginals more than twice as likely (OR: 2.26, 95% CI: 1.66-3.08) to report being feared by others. Asians were not statistically different from Whites. With two exceptions (binge drinking and physical activity), discrimination was associated with chronic conditions and their risk factors (OR for any chronic condition: 1.78, 95% CI: 1.52-2.08). Initial results suggest that in Canada, experience of discrimination is a determinant of chronic disease and chronic disease risk factors, and Blacks and Aboriginals are far more exposed to experiences of discrimination.

How does the social "get under the gums"? The role of socio-economic position in the oral-systemic health link.

OBJECTIVES: To evaluate the extent of association between systemic inflammation and periodontal disease in American adults, and to assess whether socio-economic position mediated this relationship. METHODS: We used data from the National Health and Nutrition Examination Survey (NHANES IV) (2001-2010). Systemic inflammation was defined by individual and aggregate (cumulative inflammatory load) biomarkers (C-reactive protein, white blood cell counts, neutrophil counts, and neutrophil:lymphocyte ratio). Loss of attachment and bleeding on probing were used to define periodontal disease. Poverty:income ratio and education were indicators of socio-economic position. Covariates included age, sex, ethnicity, smoking, alcohol, and attendance for dental treatment. Univariate and multivariable logistic regressions were constructed to assess the relationships of interest. RESULTS: In a total of 2296 respondents, biomarkers of systemic inflammation and cumulative inflammatory load were significantly associated with periodontal disease after adjusting for age, sex, and behavioural factors. Socio-economic position attenuated the association between markers of systemic inflammation and periodontal disease in the fully adjusted model. CONCLUSION: Socio-economic position partly explains how systemic inflammation and periodontal disease are coupled, and may thus have a significant role in the mechanisms linking oral and non-oral health conditions. It is of critical importance that the social and living conditions are taken into account when considering prevention and treatment strategies for inflammatory diseases, given what appears to be their impactful effect on disease processes.

Evaluating the Health Impact of Large-Scale Public Policy Changes: Classical and Novel Approaches.

Large-scale public policy changes are often recommended to improve public health. Despite varying widely-from tobacco taxes to poverty-relief programs-such policies present a common dilemma to public health researchers: how to evaluate their health effects when randomized controlled trials are not possible. Here, we review the state of knowledge and experience of public health researchers who rigorously evaluate the health consequences of large-scale public policy changes. We organize our discussion by detailing approaches to address three common challenges of conducting policy evaluations: distinguishing a policy effect from time trends in health outcomes or preexisting differences between policy-affected and -unaffected communities (using difference-in-differences approaches); constructing a comparison population when a policy affects a population for whom a well-matched comparator is not immediately available (using propensity score or synthetic control approaches); and addressing unobserved confounders by utilizing quasi-random variations in policy exposure (using regression discontinuity, instrumental variables, or near-far matching approaches).

Equally inequitable? A cross-national comparative study of racial health inequalities in the United States and Canada.

Prior research suggests that racial inequalities in health vary in magnitude across societies. This paper uses the largest nationally representative samples available to compare racial inequalities in health in the United States and Canada. Data were obtained from ten waves of the National Health Interview Survey (n = 162,271,885) and the Canadian Community Health Survey (n = 19,906,131) from 2000 to 2010. We estimated crude and adjusted odds ratios, and risk differences across racial groups for a range of health outcomes in each country. Patterns of racial health inequalities differed across the United States and Canada. After adjusting for covariates, black-white and Hispanic-white inequalities were relatively larger in the United States, while aboriginal-white inequalities were larger in Canada. In both countries, socioeconomic factors did not explain inequalities across racial groups to the same extent. In conclusion, while racial inequalities in health exist in both the United States and Canada, the magnitudes of these inequalities as well as the racial groups affected by them, differ considerably across the two countries. This suggests that the relationship between race and health varies as a function of the societal context in which it operates.

Visible and Invisible Trends in Black Men's Health: Pitfalls and Promises for Addressing Racial, Ethnic, and Gender Inequities in Health.

Over the past two decades, there has been growing interest in improving black men's health and the health disparities affecting them. Yet, the health of black men consistently ranks lowest across nearly all groups in the United States. Evidence on the health and social causes of morbidity and mortality among black men has been narrowly concentrated on public health problems (e.g., violence, prostate cancer, and HIV/AIDS) and determinants of health (e.g., education and male gender socialization). This limited focus omits age-specific leading causes of death and other social determinants of health, such as discrimination, segregation, access to health care, employment, and income. This review discusses the leading causes of death for black men and the associated risk factors, as well as identifies gaps in the literature and presents a racialized and gendered framework to guide efforts to address the persistent inequities in health affecting black men.

Using Decomposition Analysis to Identify Modifiable Racial Disparities in the Distribution of Blood Pressure in the United States.

To lower the prevalence of hypertension and racial disparities in hypertension, public health agencies have attempted to reduce modifiable risk factors for high blood pressure, such as excess sodium intake or high body mass index. In the present study, we used decomposition methods to identify how population-level reductions in key risk factors for hypertension could reshape entire population distributions of blood pressure and associated disparities among racial/ethnic groups. We compared blood pressure distributions among non-Hispanic white, non-Hispanic black, and Mexican-American persons using data from the US National Health and Nutrition Examination Survey (2003-2010). When using standard adjusted logistic regression analysis, we found that differences in body mass index were the only significant explanatory correlate to racial disparities in blood pressure. By contrast, our decomposition approach provided more nuanced revelations; we found that disparities in hypertension related to tobacco use might be masked by differences in body mass index that significantly increase the disparities between black and white participants. Analysis of disparities between white and Mexican-American participants also reveal hidden relationships between tobacco use, body mass index, and blood pressure. Decomposition offers an approach to understand how modifying risk factors might alter population-level health disparities in overall outcome distributions that can be obscured by standard regression analyses.