Differential vulnerability and susceptibility: how to make use of recent development in our understanding of mediation and interaction to tackle health inequalities

Is the theory of collectivity of drinking cultures valid across educational groups?

Introduction

To explore whether Skog's theory of collectivity of drinking cultures is valid across groups with different socioeconomic position (SEP).

Methods

Individual‐level information on alcohol consumption and SEP for the years 2004–2014 were retrieved from the Monitoring Project; a nationally representative monthly alcohol use survey. The analytical sample consisted of 162 369 respondents aged 25–79 years. SEP was measured by education level. Alcohol use was measured by yearly volume of consumption and frequency of heavy episodic drinking (HED). Respondents were divided into six SEP‐groups based on their education level and sex. Mean yearly volume consumption and prevalence of monthly HED was calculated for each group and graphically plotted against the overall mean volume of consumption.

Results

The yearly changes in overall mean consumption during the study period reflected a collective shift in drinking across groups with basic, intermediate and high education. There were also indications that changes in overall mean consumption reflected collective shifts in the prevalence of HED across the SEP‐groups. Moreover, while the magnitude of the associations for both average volume and HED differed somewhat in strength across the SEP‐groups, they were clearly in the same, positive, direction.

Discussion and Conclusions

Our findings add support for including a socioeconomic dimension to Skog's theory of collectivity of drinking cultures. Future studies should replicate our analyses on cases and periods with more tangible changes in the price and availability of alcohol.

The Design, Content and Delivery of Relationship and Sexuality Education Programmes for People with Intellectual Disabilities: A Systematic Review of the International Evidence

There is growing empirical evidence regarding the relationship and sexuality experiences and needs of children, young people and adults with intellectual disabilities. A total of twelve papers met the inclusion criteria regarding relationship and sexuality education (RSE) programmes specific to the needs of this population. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed and quality appraisal undertaken. The four themes identified were principles informing RSE programme development, design and content of RSE programmes, delivery of RSE programmes and evaluation of RSE programmes. The discussion presents areas that need to be addressed to ensure that people with intellectual disabilities, their families, carers and professionals are fully involved in the design and delivery of RSE programmes. Further research is required to identify the impact of the programmes and the sustained outcomes achieved. Recommendations are made regarding the activities required to enable the development of evidence-based and person-centred approaches to relationship and sexuality programmes.

Education differences in women's body weight trajectories: The role of motherhood

Studies have found that education differences in women's body weight increase until middle adulthood. The explanatory mechanisms behind this increase are not well-understood. This study examined the role of education differences in the prevalence of motherhood as a risk factor for weight gain and in vulnerability to its effects on weight gain. We used longitudinal data from the German Socio-economic Panel Study. Our sample included 2,668 women aged between 17 and 45 and observed at least twice between 2002 and 2016 (n = 13,899 panel observations). We used OLS regression models to estimate initial education differences in body weight and fixed-effects panel regression models to estimate education differences in body-weight trajectories. Motherhood was associated with increasing body weight, and the effects of motherhood on weight gain varied by education. Motherhood partially accounted for the increase of education differences during reproductive age. Until the age of 30, differences in the prevalence of motherhood accounted for about 20% of the bodyweight gap between lower and higher educated women. From age 35 until 45, differential vulnerability to the effects of motherhood on body weight explained about 15% of the education gap in body weight.

Education and incident type 2 diabetes: quantifying the impact of differential exposure and susceptibility to being overweight or obese

AIMS/HYPOTHESIS

Educational inequality in type 2 diabetes incidence is evident in many high-income countries. Previous studies have shown that differential exposure to being overweight/obese across educational groups may partly explain this inequality. Whether differential susceptibility to being overweight/obese across educational groups contributes to this inequality has been investigated less frequently, even though it is a plausible mechanism. The two mechanisms may even be highly intertwined. In this longitudinal cohort study, we investigated the simultaneous contribution of differential exposure and differential susceptibility to being overweight/obese to educational inequality in type 2 diabetes incidence.

METHODS

The study population comprised 53,159 Danish men and women aged 50-64 years at baseline who were followed for a mean of 14.7 years. We estimated rate differences of type 2 diabetes by education level per 100,000 person-years. Using counterfactual mediation analysis, these rate differences were decomposed into proportions attributable to differential exposure, differential susceptibility and all other pathways, respectively. We compared this approach with conventional approaches to mediation and interaction analysis.

RESULTS

Compared with a high level of education, a low education level was associated with 454 (95% CI 398, 510) additional cases of type 2 diabetes, and a medium education level with 316 (CI 268, 363) additional cases. Differential exposure to being overweight/obese accounted for 37% (CI 31%, 45%) of the additional cases among those with a low education level and 29% (CI 24%, 36%) of the additional cases among those with a medium education level. Differential susceptibility accounted for 9% (CI 4%, 14%) and 6% (CI 3%, 10%) of the additional cases among those with a low and medium education level, respectively. Compared with the counterfactual approach, the conventional approaches suggested stronger effects of both mechanisms.

CONCLUSIONS/INTERPRETATION

Differential exposure and susceptibility to being overweight/obese are both important mechanisms in the association between education and type 2 diabetes incidence.

Decomposing the educational gradient in allostatic load across European populations. What matters the most: differentials in exposure or in susceptibility?

Background

We investigate whether socially disadvantaged individuals are more susceptible to the detrimental effects of smoking and alcohol intake on allostatic load (AL), a marker of physiological ‘wear and tear’, resulting from adaptation to chronic stress.

Methods

In a cross-sectional analysis, 27 019 men and 26 738 women aged 35–74 years were identified from 21 European cohorts in the BiomarCaRE consortium. We defined three educational classes (EDs) according to years of schooling and an AL score as the sum of z-scores of eight selected biomarkers from the cardiovascular, metabolic and inflammatory systems. We used the Oaxaca-Blinder decomposition to disentangle the ED gradient in AL score into the differential exposure (DE, attributable to different distribution of smoking and alcohol intake across EDs) and the differential susceptibility (DS, attributable to a different effect of risk factors on AL across EDs) components.

Results

Less-educated men (mean AL difference: 0.68, 95% CI 0.57 to 0.79) and women (1.52, 95% CI 1.40 to 1.64) had higher AL scores. DE accounted for 7% and 6% of the gradient in men and women, respectively. In men, combining smoking and alcohol intake, DS accounted for 42% of the gradient (smoking DS coefficient=0.177, 26% of the gradient; alcohol DS coefficient=0.109; 16%, not statistically significant). DS contribution increased to 69% in metabolic markers. DS estimates were consistent across age groups, irrespective of comorbidities and robust to unmeasured confounding. No DS was observed in women.

Conclusions

In men, a DS mechanism substantially contributes to the educational class gradient in allostatic load.

Mental health and the risk of negative social life events: A prospective cohort study among the adult Danish population

Background: The consequences of poor mental health on morbidity and mortality are well established. However, studies prospectively examining the consequences on social life events are lacking. This study prospectively examines the risk of various social life events (educational attainment, employment status, marital status and parenthood) defined in administrative registers by mental health status at baseline defined by the MCS-12 in the Danish adult population. Methods: The analysis is based on data from the Danish National Health Survey 2010. A total of 177,639 individuals completed the questionnaire (59.5% of the sample). MCS-12 was used to categorise participants according to mental health status (poor, moderate and good). Survey data were linked to administrative registers at the individual level and followed for a minimum of 4 years. Cox proportional hazards models were used to prospectively examine the risk of various social life events according to mental health status at baseline. Results: Individuals with poor mental health and, to a certain degree, individuals with moderate mental health were less likely to experience positive life events such as progression in educational level, getting married, being employed and becoming a parent and were more likely to experience negative life events such as becoming unemployed and divorced/widowed. Conclusions: Mental health status is associated with educational attainment, employment status, marital status and parenthood. These results add to a growing body of evidence indicating that poor mental health is associated with substantial societal-level impairments that should be taken into consideration when making decisions regarding allocation of treatment and research resources.

How does socioeconomic development in Brazil shape social inequalities in diabetes?

Many countries, including Brazil, are facing growing social inequalities in diabetes prevalence. The different states in Brazil represent different levels of development and by comparing diabetes inequalities across states we aim to get a better understanding of how educational inequalities in diabetes are linked to social development. We use the latest cross-sectional national health survey of Brazil - PNS-2013 (N = 60,202) and analyse the disparities in diabetes as well as the differential exposure and susceptibility to the effect of obesity across states for men and women. Among women in high-HDI states the prevalence of diabetes is 11.7 percentage units (CI: 9.3; 14.0) higher among the lowest compared to the highest educated. In less-developed states the disparity is smaller. Among men, there is no social gradient found for diabetes, but obesity is positively associated with education. The association between obesity and diabetes is stronger among the low educated particularly for men in high-HDI states. Here the interaction effect between low education and obesity is 11.7 (CI 8.1; 15.4) percentage units. The fact that economic development is associated with increasingly unequal levels of diabetes and with unequal levels of exposure and susceptibility to obesity indicates that other interacting determinants are important for the development of the diabetes epidemic in Brazil.

Taxation of unprocessed sugar or sugar-added foods for reducing their consumption and preventing obesity or other adverse health outcomes

BACKGROUND

Global prevalence of overweight and obesity are alarming. For tackling this public health problem, preventive public health and policy actions are urgently needed. Some countries implemented food taxes in the past and some were subsequently abolished. Some countries, such as Norway, Hungary, Denmark, Bermuda, Dominica, St. Vincent and the Grenadines, and the Navajo Nation (USA), specifically implemented taxes on unprocessed sugar and sugar-added foods. These taxes on unprocessed sugar and sugar-added foods are fiscal policy interventions, implemented to decrease their consumption and in turn reduce adverse health-related, economic and social effects associated with these food products.

OBJECTIVES

To assess the effects of taxation of unprocessed sugar or sugar-added foods in the general population on the consumption of unprocessed sugar or sugar-added foods, the prevalence and incidence of overweight and obesity, and the prevalence and incidence of other diet-related health outcomes.

SEARCH METHODS

We searched CENTRAL, Cochrane Database of Systematic Reviews, MEDLINE, Embase and 15 other databases and trials registers on 12 September 2019. We handsearched the reference list of all records of included studies, searched websites of international organisations and institutions, and contacted review advisory group members to identify planned, ongoing or unpublished studies.

SELECTION CRITERIA

We included studies with the following populations: children (0 to 17 years) and adults (18 years or older) from any country and setting. Exclusion applied to studies with specific subgroups, such as people with any disease who were overweight or obese as a side-effect of the disease. The review included studies with taxes on or artificial increases of selling prices for unprocessed sugar or food products that contain added sugar (e.g. sweets, ice cream, confectionery, and bakery products), or both, as intervention, regardless of the taxation level or price increase. In line with Cochrane Effective Practice and Organisation of Care (EPOC) criteria, we included randomised controlled trials (RCTs), cluster-randomised controlled trials (cRCTs), non-randomised controlled trials (nRCTs), controlled before-after (CBA) studies, and interrupted time series (ITS) studies. We included controlled studies with more than one intervention or control site and ITS studies with a clearly defined intervention time and at least three data points before and three after the intervention. Our primary outcomes were consumption of unprocessed sugar or sugar-added foods, energy intake, overweight, and obesity. Our secondary outcomes were substitution and diet, expenditure, demand, and other health outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all eligible records for inclusion, assessed the risk of bias, and performed data extraction.Two review authors independently assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We retrieved a total of 24,454 records. After deduplicating records, 18,767 records remained for title and abstract screening. Of 11 potentially relevant studies, we included one ITS study with 40,210 household-level observations from the Hungarian Household Budget and Living Conditions Survey. The baseline ranged from January 2008 to August 2011, the intervention was implemented on September 2011, and follow-up was until December 2012 (16 months). The intervention was a tax - the so-called 'Hungarian public health product tax' - on sugar-added foods, including selected foods exceeding a specific sugar threshold value. The intervention includes co-interventions: the taxation of sugar-sweetened beverages (SSBs) and of foods high in salt or caffeine. The study provides evidence on the effect of taxing foods exceeding a specific sugar threshold value on the consumption of sugar-added foods. After implementation of the Hungarian public health product tax, the mean consumption of taxed sugar-added foods (measured in units of kg) decreased by 4.0% (standardised mean difference (SMD) -0.040, 95% confidence interval (CI) -0.07 to -0.01; very low-certainty evidence). The study was at low risk of bias in terms of performance bias, detection bias and reporting bias, with the shape of effect pre-specified and the intervention unlikely to have any effect on data collection. The study was at unclear risk of attrition bias and at high risk in terms of other bias and the independence of the intervention. We rated the certainty of the evidence as very low for the primary and secondary outcomes. The Hungarian public health product tax included a tax on sugar-added foods but did not include a tax on unprocessed sugar. We did not find eligible studies reporting on the taxation of unprocessed sugar. No studies reported on the primary outcomes of consumption of unprocessed sugar, energy intake, overweight, and obesity. No studies reported on the secondary outcomes of substitution and diet, demand, and other health outcomes. No studies reported on differential effects across population subgroups. We could not perform meta-analyses or pool study results.

AUTHORS' CONCLUSIONS

There was very limited evidence and the certainty of the evidence was very low. Despite the reported reduction in consumption of taxed sugar-added foods, we are uncertain whether taxing unprocessed sugar or sugar-added foods has an effect on reducing their consumption and preventing obesity or other adverse health outcomes. Further robustly conducted studies are required to draw concrete conclusions on the effectiveness of taxing unprocessed sugar or sugar-added foods for reducing their consumption and preventing obesity or other adverse health outcomes.

The wellbeing of working-age adults with and without disability in the UK: Associations with age, gender, ethnicity, partnership status, educational attainment and employment status

BACKGROUND

Few population-based studies have examined the association between disability and personal wellbeing (PWB) among working-age adults.

OBJECTIVE/HYPOTHESIS

To determine: (1) the magnitude of differences in wellbeing between working-age adults with and without disability in contemporary samples representative of the UK population; and (2) whether the size of any observed differences between people with and without disability is moderated by age, gender, ethnicity, partnership status, educational attainment or employment status.

METHODS

Secondary analysis of data from three national cross-sectional surveys.

RESULTS

In each survey, people with disability scored lower than people without disability on all four indicators of PWB. Adjusting for the main effects of potentially moderating variables reduced the effect size of disability on PWB by an average of 24%. Subsequently adjusting for the two-way interaction terms between disability and potentially moderating variables reduced the effect size of disability (main effect) on PWB by an additional average of 73%. PWB among people with disability was significantly lower for: (1) men; (2) younger people; (3) those who belong to the majority ethnic group (white British); (4) those without a partner; and (5) people with lower socio-economic position.

CONCLUSIONS

Our findings indicate that demographic characteristics and exposure to specific social determinants of poor health play a major role in the negative association between disability and personal wellbeing. A more sophisticated understanding of how social determinants interact to produce inequities associated with identities such as disability, gender, race, sexuality, and class (intersectionality) can inform effective policy interventions.

Socio-economic disparities in the association of diet quality and type 2 diabetes incidence in the Dutch Lifelines cohort

BACKGROUND

It is unknown whether a socio-economic difference exists in the association of diet quality with type 2 diabetes incidence, nor how diet influences the socioeconomic inequality in diabetes burden.

METHODS

In 91,025 participants of the population-based Lifelines Cohort (aged ≥30, no diabetes or cardiovascular diseases at baseline), type 2 diabetes incidence was based on self-report, fasting glucose ≥ 7·0 mmol/l and/or HbA1c ≥ 6·5%. The evidence-based Lifelines Diet Score was calculated with data of a 110-item food frequency questionnaire. Socio-economic status (SES) was defined by educational level. Cox proportional hazards models were adjusted for age, gender, smoking, energy intake, alcohol intake and physical activity.

FINDINGS

In 279,796 person-years of follow-up, 1045 diabetes cases were identified. Incidence rate was 5·7, 3·2 and 2·4 cases/1000 person-years in low, middle and high SES, respectively. Diet was associated with greater diabetes risk (HR(95%CI) in Q1 (poor diet quality) vs. Q5 (high diet quality) = 2·11 (1·70-2·62)). SES was a moderator of the association(p_INTERACTION = 0·038). HRs for Q1 vs. Q5 were 1·66 (1·22-2·.27) in low, 2·76 (1·86-4·08) in middle and 2·46 (1·53-3·97) in high SES. With population attributable fractions of 14·8%, 40·1% and 37·3%, the expected number of cases/1000 person-years preventable by diet quality improvement was 0·85 in low, 1·28 in middle and 0·90 in high SES.

INTERPRETATION

Diet quality improvement can potentially prevent one in three cases of type 2 diabetes, but because of a smaller impact in low SES, it will not narrow the socioeconomic health gap in diabetes burden.

FUNDING

None.

Does the neighborhood food environment contribute to ethnic inequalities in fast-food intake? findings from the ORiEL study

The neighborhood food environment may contribute to ethnic inequalities in diet. Using data from 1389 participants in the Olympic Regeneration in East London (UK) study we assessed whether ethnic inequalities in neighborhood availability of fast-food restaurants mediated and/or modified ethnic inequalities in fast-food intake in 13–15 year-old adolescents. We compared the proportion of high fast-food consumers across “White UK”, “Black”, and “South Asian” ethnic categories. We used Poisson regression with robust standard errors to assess direct and indirect effects (mediation analysis) and risk ratios of high fast-food intake by ethnic category and fast-food restaurant availability level (effect measure modification analysis). There were ethnic inequalities in high fast-food intake, with risk ratios in adolescents of Black and South Asian background of 1.53 (95% CI: 1.25, 1.87) and 1.71 (95% CI: 1.41, 2.07) respectively compared to White UK participants. We found no evidence of a mediating effect by fast-food restaurant availability, but found some evidence of effect measure modification: ethnic inequalities in fast-food intake were largest in neighborhoods lacking fast-food restaurants, and narrowed as availability increased. Future research should explore why ethnic minorities are more likely to be high fast-food consumers than the majority ethnic group, especially when fast-food restaurant availability is lowest.

An intersectional approach to understandings of mental health inequalities among men with disability

Disability is a key social identity or social category that is associated with significant social disadvantage. For men, having a disability can be discordant with their masculine identity. Self-reliance is one component of masculinity that is known to be important to men with disabilities, however it is also known to be associated with adverse mental health outcomes in the broader adult male population. Intersectionality approaches offer a means of examining the way that the effect of self-reliance on mental health might vary between those with and without a disability. Among a sample of 12,052 men aged 18-55 years from the Ten-to-Men study, we used effect measure modification (EMM) to examine the way that self-reliance modifies the relationship between disability and depressive symptoms. Disability was assessed using the Washington Group Short Set of questions, which capture functional limitations. Results showed that men with disabilities who reported higher conformity to self-reliance norms had much worse mental health than non-disabled men with low conformity to self-reliance, as measured in terms of depressive symptoms (PRR: 9.40, 95%CI 7.88, 11.22, p-value<0.001). We found evidence of positive EMM of depressive symptoms by conformity to self-reliance on the additive scale (RERI: 2.84, 95%CI 1.26, 4.42, p-value<0.001). These results provide evidence that high conformity to self-reliance norms exerts a particularly damaging effect on the mental health of men with disabilities. Given that men with disabilities are more likely to rely on help and support from others, these results provide important insights for the delivery of services to men with disability.

Generational differences in longitudinal blood pressure trajectories by geographic region during socioeconomic transitions in China

OBJECTIVES

To examine generational differences in longitudinal blood pressure trajectories by region following socioeconomic transitions, which is important for establishing the population risk of cardiovascular diseases (CVDs).

METHODS

With data from the China Health and Nutrition Survey (1991-2011), we used multilevel growth-curve models to estimate systolic/diastolic blood pressure (SBP/DBP) levels at the mean age and rates of change by cohort (born between 1931 and 1980), region, and sex.

RESULTS

Younger cohorts generally had higher SBP/DBP levels at 44.5 years but lower growth rates in SBP/DBP than older cohorts. They became prehypertensive (SBP ≥ 120 mm Hg or DBP ≥ 80 mm Hg) at an earlier age. The upward shift of SBP/DBP trajectories across cohorts was more pronounced in the Coastal and Southern Mountainous Regions than the Northeastern and Inland Regions, and for males versus females.

CONCLUSIONS

Younger cohorts have a longer lifetime duration of being susceptible to CVDs, posing warnings for an increased burden of CVDs. Generational differences in BP trajectories and geographic and sex variations in the cohort trends highlight the need for tailored interventions to tackle the generation, region, and sex-based risk of CVDs.

Statistical Approaches for Investigating Periods of Susceptibility in Children's Environmental Health Research

PURPOSE OF REVIEW

Children's environmental health researchers are increasingly interested in identifying time intervals during which individuals are most susceptible to adverse impacts of environmental exposures. We review recent advances in methods for assessing susceptible periods.

RECENT FINDINGS

We identified three general classes of modeling approaches aimed at identifying susceptible periods in children's environmental health research: multiple informant models, distributed lag models, and Bayesian approaches. Benefits over traditional regression modeling include the ability to formally test period effect differences, to incorporate highly time-resolved exposure data, or to address correlation among exposure periods or exposure mixtures. Several statistical approaches exist for investigating periods of susceptibility. Assessment of susceptible periods would be advanced by additional basic biological research, further development of statistical methods to assess susceptibility to complex exposure mixtures, validation studies evaluating model assumptions, replication studies in different populations, and consideration of susceptible periods from before conception to disease onset.

Socioeconomic status, life expectancy and mortality in a universal healthcare setting: An individual-level analysis of >6 million Catalan residents

We evaluated the association between individual-level socioeconomic status (SES), life expectancy, and mortality, in adult men and women from the general population living in Catalonia, a universal healthcare coverage setting. We used the Catalan Health Surveillance System database, which includes individual-level information on sociodemographic characteristics and mortality for all residents of Catalonia (Spain). We categorized individuals as high, medium, low or very low SES based on annual personal income and welfare receipt. We used 2016 mortality data to estimate life expectancy at age 18, and the probability of death by age, sex and SES categories. We followed a total of 6,027,424 Catalan residents in 2016. Men and women of very low SES had 12.0 and 9.4 years lower life expectancy compared to men and women of high SES, respectively. Low SES was also strongly associated with mortality in both men and women of any age. In the entire adult population of Catalonia, despite the availability of universal, high quality healthcare coverage, low SES is associated with lower life expectancy and higher mortality. Solutions to these large inequalities may combine tailored health promotion and management interventions, with solutions coming from outside of the health sector.

How does perinatal maternal mental health explain early social inequalities in child behavioural and emotional problems? Findings from the Wirral Child Health and Development Study

BACKGROUND

This study aimed to assess how maternal mental health mediates the association between childhood socio-economic conditions at birth and subsequent child behavioural and emotional problem scores.

METHODS

Analysis of the Wirral Child Health and Development Study (WCHADS), a prospective epidemiological longitudinal study of the early origins of child mental health (n = 664). Household income at 20-weeks gestation, a measure of socio-economic conditions (SECs) in pregnancy, was the main exposure. The outcome measure was externalising and internalising problems, as measured by the Child Behaviour Checklist at 5 years. We assessed the association of household income with child behavioural outcomes in sequential linear models adjusting for maternal mental health in the pre- and post- natal period.

RESULTS

Children of mothers in more disadvantaged households had higher scores for externalising behaviour with a difference of 3.6 points comparing the most affluent to the most disadvantaged families (the socio-economic (SEC) gap). In our regression model adjusting for baseline confounders, comparing children of mothers in the most disadvantaged households to the least disadvantaged, we found that most disadvantaged children scored 45 percentage points (95% CI 9, 93) higher for externalising problems, and 42% of this difference was explained in the fully adjusted model. Adjusting for prenatal maternal depressive symptomology attenuated the SEC gap in externalising problems by about a third, rendering the association non-significant, whilst adjusting for pre- and post-natal maternal mental health attenuated the SEC gap by 42%. There was no significant relationship between household income and internalising problems.

CONCLUSION

Social disadvantage is associated with higher child externalising behaviour problems score at age 5, and about 40% of this was explained by maternal perinatal mental health. Policies supporting maternal mental health in pregnancy are important to address the early emergence of inequalities in child mental health.

Theorising social class and its application to the study of health inequalities

The literature on health inequalities often uses measures of socio-economic position pragmatically to rank the population to describe inequalities in health rather than to understand social and economic relationships between groups. Theoretical considerations about the meaning of different measures, the social processes they describe, and how these might link to health are often limited. This paper builds upon Wright's synthesis of social class theories to propose a new integrated model for understanding social class as applied to health. This model incorporates several social class mechanisms: social background and early years' circumstances; Bourdieu's habitus and distinction; social closure and opportunity hoarding; Marxist conflict over production (domination and exploitation); and Weberian conflict over distribution. The importance of discrimination and prejudice in determining the opportunities for groups is also explicitly recognised, as is the relationship with health behaviours. In linking the different social class processes we have created an integrated theory of how and why social class causes inequalities in health. Further work is required to test this approach, to promote greater understanding of researchers of the social processes underlying different measures, and to understand how better and more comprehensive data on the range of social class processes these might be collected in the future.

Intersectional decomposition analysis with differential exposure, effects, and construct

In recent years a wide array of proposals for bringing intersectional perspectives into quantitative studies of health disparities have appeared, from studies of interaction, predictive discrimination, to mediation. Bauer and Scheim, in a companion set of articles, extend these proposals by developing new attribution-blind measures of perceived discrimination and using VanderWeele's 3-way decomposition to quantify its contribution to disparities through differential exposure and differential effects (sometimes called differential vulnerability or susceptibility). In this commentary, after providing an overview of causal inference interpretations with social characteristics, we provide a broad overview of old and new decomposition methods in the social sciences literature and contrast their strengths and weaknesses for studying intersectional inequalities. We then examine how different forms of differential effects can be expressed within these decompositions and discuss their utility for the purpose of informing interventions for reducing disparities. Last, we discuss the tension in social sciences research when prominent explanatory variables represent constructs that are only defined or exist for certain marginalized populations and may not neatly fit within the decomposition methods framework. Through these discussions, we aim to provide greater conceptual clarity for applied researchers who are interested in using decomposition methods and other approaches to advance intersectional equity.

The syndemics of diabetes and depression in Brazil - An epidemiological analysis

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An epidemiological model of causal pathways in the syndemic of diabetes and depression is presented.

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Depression and diabetes are clustering in the adult Brazilian population partly due to shared social and behavioural causes.

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There is an interaction between depression and diabetes in their association with disability.

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There is a differential susceptibility to the effect of obesity on diabetes across levels of education and depression.

Understanding social inequalities in Zika infection and its consequences: A model of pathways and policy entry-points

The health consequences of arbovirus infections such as dengue fever (DENV), Chikungunya (CHIKV) and Zika (ZIKV) has in recent years become a public health challenge, due to failure of prevention followed by increased incidence and pronounced social inequality in occurrence and consequences. This motivates a more systematic analysis of the potential mechanisms and pathways that generate these inequalities. We present in the paper a model that delineates five possible mechanisms driving the inequality of ZIKV and congenital Zika syndrome (CZS). They include differential exposure to bad housing and sanitary conditions, differential exposure to vector density and virus, differential vulnerability to the health effects of exposure to virus, differential intrauterine susceptibility to the teratogenic effects of ZIKV infection and differential social consequences of caring for a disabled child. For each mechanism, we present empirical evidence or need for more research as well as a discussion about policy implications.