Promoting the health of vulnerable populations: Three steps towards a systems-based re-orientation of public health intervention research.

This paper proposes a novel framework for the development of interventions in vulnerable populations. The framework combines a complex systems lens with syndemic theory. Whereas funding bodies, research organizations and reporting guidelines tend to encourage intervention research that (i) focuses on singular and predefined health outcomes, (ii) searches for generalizable cause-effect relationships, and (iii) aims to identify universally effective interventions, the paper suggests that a different direction is needed for addressing health inequities: We need to (i) start with exploratory analysis of population-level data, and (ii) invest in contextualized in-depth knowledge of the complex dynamics that produce health inequities in specific populations and settings, while we (iii) work with stakeholders at multiple levels to create change within systems.

Hospitalisation patterns among children exposed to childhood adversity: a population-based cohort study of half a million children.

BACKGROUND: Children who are exposed to adversities might be more susceptible to disease development during childhood and in later life due to impaired physiological and mental development. To explore this hypothesis, we assessed hospitalisation patterns through childhood and into adult life among those exposed to different trajectories of adversities during childhood. METHODS: For this population-based cohort study, we used annually updated data from Danish nationwide registers covering more than half a million children (aged 0-15 years) born between 1994 and 2001. Children who were alive and resident in Denmark on their 16th birthday were included in the analysis. Cluster analysis was used to divide children into five distinct trajectories according to their experience of childhood adversities, including poverty and material deprivation, loss or threat of loss within the family, and aspects of family dynamics. To describe comprehensively the disease patterns experienced by these groups of children, we assessed the associations of each adversity trajectory with hospital admission patterns according to the entire spectrum of disease diagnoses in the International Classification of Diseases 10th edition, from birth to 24 years of age, using survival models. FINDINGS: 508 168 children born between Jan 1, 1994, and Dec 31, 2001, were followed up until Dec 31, 2018, capturing more than 3·8 million hospital admissions from birth to early adulthood. Hospitalisation rates were consistently higher in all four adversity groups compared with the low adversity group. The high adversity group (14 577 children, 3%), who were exposed to adversities of deprivation, family loss, and negative family dynamics, had a markedly higher rate of hospitalisations across all ages. For example, we observed 243 additional hospital admissions per 1000 person-years (95% CI 238-248) in the high versus low adversity group for those aged 16-24 years. These associations were particularly strong for diagnoses related to injuries, unspecified symptoms, and factors influencing health service contacts (eg, health screening and observation). They also covered a considerable burden of respiratory and infectious diseases, congenital malformations, diseases of the nervous system (especially in early life), mental and behavioural diagnoses, and diagnoses related to pregnancy and childbirth in early adult life. INTERPRETATION: The close linkage between childhood adversities and poor lifelong health outcomes highlights a need for public health and policy attention on improving the socioeconomic circumstances children are born into to prevent the early emergence of health inequalities. FUNDING: None.

The SmartSleep Experiment: Evaluation of changes in night-time smartphone behavior following a mass media citizen science campaign.

The increasing 24-hour smartphone use is of public health concern. This study aims to evaluate whether a massive public focus on sleep and smartphone use generated through a large-scale citizen science project, the SmartSleep Experiment, influence participants' night-time smartphone behavior. A total of 8,894 Danish adults aged 16 and above participated in the SmartSleep Experiment, a web-based survey on smartphones and sleep behavior. The survey was carried out for one week in 2018, combined with an extensive national mass media campaign focusing on smartphone behaviors and sleep. A follow-up survey aimed at evaluating whether survey-participants had changed their night-time smartphone behavior was carried out two weeks after the campaign. A total of 15% of the participants who used their smartphone during sleep hours at baseline had changed their night-time smartphone behavior, and 83% of those indicated that they used their smartphone less at follow-up. The participants who had changed their smartphone behavior had primarily taken active precautions to avoid night-time smartphone use, e.g., activating silent mode (36%) or reduced their smartphone use before (50%) and during sleep hours (52%). The reduction in sleep problems (54%), recognition of poor smartphone behavior (48%), and the increased focus on night-time smartphone use (42%) were motivational factors for these behavior changes. Using citizen science and mass media appeared to be associated with changes in night-time smartphone behavior. Public health projects may benefit from combining citizen science with other interventional approaches.

Workplace Violence and Long-term Sickness Absence: Assessment of the Potential Buffering Effect of Social Support in Two Occupational Cohort Studies.

OBJECTIVES: We aimed to determine the effect of workplace violence on long-term sickness absence, and whether social support from supervisors and colleagues buffer this effect. METHODS: Information on workplace violence and social support were derived from the Danish Work Environment Cohort Study in 2000, 2005, and 2010 and the Swedish Longitudinal Occupational Survey of Health in 2006 and 2008. Individual- and joint-effects on register-based long-term sickness absence were determined using logistic regression models for repeated measurements. Cohort-specific estimates were combined in random effect meta-analyses. RESULTS: Workplace violence and low social support were independently associated with a higher risk of long-term sickness absence, and we did not find evidence of an interaction. CONCLUSION: Exposure to workplace violence is a risk factor for long-term sickness absence while social support is associated with a lower risk of long-term sickness absence.

Economic hardship over twenty-two consecutive years of adult life and markers of early ageing: physical capability, cognitive function and inflammation.

This study assesses the associations between annual measures of economic hardship (EH) across 22 years of adulthood and objective measures of early ageing in a Danish late-middle-aged population (N = 5575). EH (years < 60% of the National median equivalized household disposable income) was experienced by 18% during 1987-2008. Four or more years in EH (reference = null years in EH) was related to poorer physical capability (chair rise: - 1.49 counts/30 s [95% confidence interval (CI) - 2.36, - 0.61], hand grip strength: - 1.22 kg [95% CI - 2.38, - 0.07], jump height: - 1.67 cm [95% CI - 2.44, - 0.91] and balance: 18% [95% CI 9, 28]), poorer cognitive function (Intelligenz-Struktur-Test: - 1.50 points [95% CI - 2.89, - 0.12]) and higher inflammatory levels (C-reactive protein: 22% [95% CI 4, 44], and Interleukin-6: 23% [95% CI 10, 39]). Comparing four EH trajectories, people with a high versus low probability of EH over time had poorer physical capability (chair rise: - 1.70 counts/30 s [95% CI - 3.38, - 0.01], grip: - 4.33 kg [95% CI - 6.50, - 2.16], jump: - 1.68 cm [95% CI - 3.12, - 0.25] and balance: 31% [95% CI 12, 52]). No associations were observed with tumour necrosis factor-α. Results were adjusted for sex, age, long-term parental unemployment/financial problems, education, baseline income and cohort. This study suggested EH for four or more years to be associated with poorer physical capability, cognitive function and increased inflammatory levels in midlife. High probability of EH across adulthood was similarly related to poorer physical capability and CRP, but not cognitive function and the remaining inflammatory markers. In conclusion, preventive initiatives focusing on reducing the burden of sustained economic hardship may lead to increased healthy ageing.

Psychosocial working conditions and depressive disorder: disentangling effects of job control from socioeconomic status using a life-course approach.

PURPOSE: Job control, the combination of skill discretion and decision authority, is considered a central component of the psychosocial working environment. This longitudinal study examines the relation between job control and risk of incident depressive disorder using a life-course approach. METHODS: We analyze data from The Danish Work Life Course Cohort study, including all Danish individuals aged 15-30 who entered the Danish labor market during 1995-2009 and were free from depressive disorder at entry (955,573 individuals). We measured job control using a job exposure matrix. Depressive disorders were measured using information from nationwide registers of psychiatric in- and outpatient admissions. Using Cox regression models we estimated the prospective association between job control and risk of incident depressive disorders. Analyses accounted for a range of potential confounders prior to workforce entry including socioeconomic status in adolescence and parental psychiatric and somatic diagnoses prior to labor market entry, together with potential confounders in adulthood including income, education, and demographics. RESULTS: Lower levels of past year job control were associated with a higher risk of depressive disorder after adjustment for all covariates (HR = 1.27, 95% CI 1.16-1.38). Results stratified by gender showed associations for both men (HR = 1.38, 95% CI 1.19-1.61) and women (HR = 1.19, 95% CI 1.08-1.32). CONCLUSIONS: Our findings suggest that the level of job control at work affects the risk of clinically diagnosed depressive disorder, and that this association is not due to confounding by socioeconomic status.

Childhood socioeconomic position and physical capability in late-middle age in two birth cohorts from the Copenhagen aging and midlife biobank.

This study examines the association between childhood socioeconomic position and objective physical capability including new functional measures of potential relevance to a population in late-middle age. The study population covers two Danish birth cohorts followed-up in the Copenhagen Aging and Midlife Biobank (age 48-58 years, 2009-2011, N = 4,204). Results from linear regression models revealed that being born in higher socioeconomic position was associated with higher jump height: Paternal occupational class four = 0.19 cm (95% confidence interval (CI): -0.44, 0.82), three = 0.59 cm (95% CI: -0.02, 1.19), two = 1.29 cm (95% CI: 0.64, 1.94), and one = 1.29 cm (95% CI: 0.45, 2.13) (reference = five); medium parental social class = 0.88 cm (95% CI: 0.03, 1.72) and high = 1.79 cm (95% CI: 0.94, 2.63) (reference = low). Higher childhood socioeconomic position was also associated with better chair rise performance and hand grip strength, while among women it was related to reduced flexibility: Medium parental social class = -1.31 cm (95% CI: -3.05, 0.42) and high = -2.20 cm (95% CI: -3.94, -0.47) (reference = low); unwed mother = 1.75 cm (95% CI: 0.36, 3.14) (reference = married). Overall, the findings suggest that higher childhood socioeconomic position is primarily related to moderately better scores in the most strenuous physical capability measures and hand grip strength among healthy adults in late-middle age.

Work-unit social capital and long-term sickness absence: a prospective cohort study of 32 053 hospital employees.

OBJECTIVE: There is a lack of studies investigating social capital at the workplace level in small and relatively homogeneous work-units. The aim of the study was to investigate whether work-unit social capital predicts a lower risk of individual long-term sickness absence among Danish hospital employees followed prospectively for 1 year. METHODS: This study is based on the Well-being in HospitAL Employees cohort. The study sample consisted of 32 053 individuals nested within 2182 work-units in the Capital Region of Denmark. Work-unit social capital was measured with an eight-item scale covering elements of trust, justice and collaboration between employees and leaders. Social capital at the work-unit level was computed as the aggregated mean of individual-level social capital within each work-unit. Data on long-term sickness absence were retrieved from the employers' payroll system and were operationalised as ≥29 consecutive days of sickness absence. We used a 12-point difference in social capital as the metric in our analyses and conducted two-level hierarchical logistic regression analysis. Adjustments were made for sex, age, seniority, occupational group and part-time work at the individual level, and work-unit size, the proportion of female employees and the proportion of part-time work at the work-unit level. RESULTS: The OR for long-term sickness absence associated with a 12-point higher work-unit social capital was 0.73 (95% CI 0.68 to 0.78). Further, we found an association between higher work-unit social capital and lower long-term sickness absence across quartiles of social capital: compared with the lowest quartile, the OR for long-term sickness absence in the highest quartile was 0.51 (95% CI 0.44 to 0.60). CONCLUSION: Our study provides support for work-unit social capital being a protective factor for individual long-term sickness absence among hospital employees in the Capital Region of Denmark.

Dual impact of organisational change on subsequent exit from work unit and sickness absence: a longitudinal study among public healthcare employees.

OBJECTIVES: We investigated work-unit exit, total and long-term sickness absence following organisational change among public healthcare employees. METHODS: The study population comprised employees from the Capital Region of Denmark (n=14 388). Data on reorganisation at the work-unit level (merger, demerger, relocation, change of management, employee layoff or budget cut) between July and December 2013 were obtained via surveys distributed to the managers of each work unit. Individual-level data on work-unit exit, total and long-term sickness absence (≥29 days) in 2014 were obtained from company registries. For exposure to any, each type or number of reorganisations (1, 2 or ≥3), the HRs and 95% CIs for subsequent work-unit exit were estimated by Cox regression, and the risk for total and long-term sickness absence were estimated by zero-inflated Poisson regression. RESULTS: Reorganisation was associated with subsequent work-unit exit (HR 1.10, 95% CI 1.01 to 1.19) in the year after reorganisation. This association was specifically important for exposure to ≥3 types of changes (HR 1.52, 95% CI 1.30 to 1.79), merger (HR 1.29, 95% CI 1.12 to 1.49), demerger (HR 1.41, 95% CI 1.16 to 1.71) or change of management (HR 1.24, 95% CI 1.11 to 1.38). Among the employees remaining in the work unit, reorganisation was also associated with more events of long-term sickness absence (OR 1.15, 95% CI 1.00 to 1.33), which was particularly important for merger (OR 1.31, 95% CI 1.00 to 1.72) and employee layoff (OR 1.31, 95% CI 1.08 to 1.59). CONCLUSIONS: Specific types of reorganisation seem to have a dual impact on subsequent work-unit exit and sickness absence in the year after change.

Understanding the relation between socioeconomic position and inflammation in post-menopausal women: education, income and occupational prestige.

Background: The role of occupational prestige, a direct measure of the perceived status of job and job holder, in inflammation is unknown. To contribute to understanding the pathways by which socioeconomic position (SEP) is associated with inflammation, we aimed to estimate the direct effects of education, income and occupational prestige on C-reactive protein (CRP) and to describe the relationship between these markers and CRP. Methods: The study was based on 2026 post-menopausal women enrolled in the Women's Health Initiative-Observational Study. Occupational prestige was determined by linking a text description of longest held occupation with a social status item from the Occupational Information Network. Path analysis was employed to estimate direct and mediated effects. Results: The study suggests that higher levels of education, income, and occupational prestige are associated with 8% (95% CI as percentage change -12, -4), 5% [95% CI (-8, -2) and 4% (95% CI - 7, -1)] lower levels of CRP, respectively. The inverse association between education and CRP was explained by the effect of education on income and occupational prestige. The effect of occupational prestige on CRP was independent of mediators in the model. Conclusions: The findings indicate that education may work to influence CRP primarily through increasing income and occupational prestige and provides evidence that occupational prestige captures a unique aspect of SEP.

Neighborhood perceptions and allostatic load: Evidence from Denmark.

An influential argument explaining why living in certain neighborhoods can become harmful to one's health maintains that individuals can perceive certain characteristics of the neighborhood as threatening and the prolonged exposure to a threatening environment could induce chronic stress. Following this line of argumentation, in the present study we test whether subjective perceptions of neighborhood characteristics relate to an objective measure of stress-related physiological functioning, namely allostatic load (AL). We use a large dataset of 5280 respondents living in different regions of Denmark and we account for two alternative mechanisms, i.e., the objective characteristics of the living environment and the socio-economic status of individuals. Our results support the chronic stress mechanisms linking neighborhood quality to health. Heightened perceptions of disorder and pollution were found related to AL and this relationship was particularly robust for women.

Early life adversity potentiates the effects of later life stress on cumulative physiological dysregulation.

BACKGROUND AND OBJECTIVES: Previous research indicates that early life adversity may heighten stress reactivity and impair mechanisms for adaptive coping, suggesting that experience of stress in early life may also potentiate adults' physiological vulnerability to stress in later life. The study tested this hypothesis by investigating whether the experience of stressful events and circumstances (SEC) in childhood or adolescence amplified the effect of adulthood SEC on physiological dysregulation (allostatic load, AL) in later midlife. DESIGN: Observational data were used in the present study. Physiological functioning was measured in later midlife (participants' age ranged from 49 to 63 years). Both childhood/adolescence and adulthood SEC were reported retrospectively on the same occasion. METHODS: Participants were 5309 Danish men and women from Copenhagen Aging and Midlife Biobank (CAMB). SEC included socioeconomic and family factors. The AL index was based on nine cardiovascular, metabolic, and immune biomarkers. RESULTS: Experience of SEC in both early life and adulthood independently predicted higher AL. In men, experience of SEC in early life also potentiated the effect of SEC in adulthood on AL. CONCLUSIONS: The results provide further insight into the mechanisms behind the "biological embedding" of childhood stress.

Social gradient in allostatic load among Danish men and women in late midlife.

OBJECTIVE: The objective of the present study is to describe the prevalence of allostatic load (AL) among Danish men and women in late midlife, and if there is a social gradient in AL. METHOD: A total of 5,420 participants from the Copenhagen Aging and Midlife Biobank (CAMB) aged 48 to 63 years (68.5% men, 31.5% women) underwent a health examination including standardized measures of height, weight, body fat, and blood pressure in 2009-2011. AL (range 0-14) was established by summing the scores of the poorest quartile for each of 14 biological variables related to the metabolic and immune systems. RESULTS: We found a social gradient in AL in late midlife among men and women living in Denmark. DISCUSSION: AL may be a potential biomarker for early aging in countries with a strong social welfare system. It is important for intervention studies to be aware of this type of biological vulnerability already present in late midlife.

Education and cause-specific mortality: the mediating role of differential exposure and vulnerability to behavioral risk factors.

BACKGROUND: Differential exposures to behavioral risk factors have been shown to play an important mediating role on the education-mortality relation. However, little is known about the extent to which educational attainment interacts with health behavior, possibly through differential vulnerability. METHODS: In a cohort study of 76,294 participants 30 to 70 years of age, we estimated educational differences in cause-specific mortality from 1980 through 2009 and the mediating role of behavioral risk factors (smoking, alcohol intake, physical activity, and body mass index). With the use of marginal structural models and three-way effect decomposition, we simultaneously regarded the behavioral risk factors as intermediates and clarified the role of their interaction with educational exposure. RESULTS: Rate differences in mortality comparing participants with low to high education were 1,277 (95% confidence interval = 1,062 to 1,492) per 100,000 person-years for men and 746 (598 to 894) per 100,000 person-years for women. Smoking was the strongest mediator for cardiovascular disease, cancer, and respiratory disease mortality when conditioning on sex, age, and cohort. The proportion mediated through smoking was most pronounced in cancer mortality as a combination of the pure indirect effect, owing to differential exposure (men, 42% [25% to 75%]; women, 36% [17% to 74%]) and the mediated interactive effect, owing to differential vulnerability (men, 18% [2% to 35%], women, 26% [8% to 50%]). The mediating effects through body mass index, alcohol intake, or physical activity were partial and varied for the causes of deaths. CONCLUSION: Differential exposure and vulnerability should be addressed simultaneously, as these mechanisms are not mutually exclusive and may operate at the same time.

Cohort profile: the Social Inequality in Cancer (SIC) cohort study.

The Social Inequality in Cancer (SIC) cohort study was established to determine pathways through which socioeconomic position affects morbidity and mortality, in particular common subtypes of cancer. Data from seven well-established cohort studies from Denmark were pooled. Combining these cohorts provided a unique opportunity to generate a large study population with long follow-up and sufficient statistical power to develop and apply new methods for quantification of the two basic mechanisms underlying social inequalities in cancer-mediation and interaction. The SIC cohort included 83 006 participants aged 20-98 years at baseline. A wide range of behavioural and biological risk factors such as smoking, physical inactivity, alcohol intake, hormone replacement therapy, body mass index, blood pressure and serum cholesterol were assessed by self-administered questionnaires, physical examinations and blood samples. All participants were followed up in nationwide demographic and healthcare registries. For those interested in collaboration, further details can be obtained by contacting the Steering Committee at the Department of Public Health, University of Copenhagen, at inan@sund.ku.dk.

Education and risk of coronary heart disease: assessment of mediation by behavioral risk factors using the additive hazards model.

Educational-related gradients in coronary heart disease (CHD) and mediation by behavioral risk factors are plausible given previous research; however this has not been comprehensively addressed in absolute measures. Questionnaire data on health behavior of 69,513 participants, 52 % women, from seven Danish cohort studies were linked to registry data on education and incidence of CHD. Mediation by smoking, low physical activity, and body mass index (BMI) on the association between education and CHD were estimated by applying newly proposed methods for mediation based on the additive hazards model, and compared with results from the Cox proportional hazards model. Short (vs. long) education was associated with 277 (95 % CI: 219, 336) additional cases of CHD per 100,000 person-years at risk among women, and 461 (95 % CI: 368, 555) additional cases among men. Of these additional cases 17 (95 % CI: 12, 22) for women and 37 (95 % CI: 28, 46) for men could be ascribed to the pathway through smoking. Further, 39 (95 % CI: 30, 49) cases for women and 94 (95 % CI: 79, 110) cases for men could be ascribed to the pathway through BMI. The effects of low physical activity were negligible. Using contemporary methods, the additive hazards model, for mediation we indicated the absolute numbers of CHD cases prevented when modifying smoking and BMI. This study confirms previous claims based on the Cox proportional hazards model that behavioral risk factors partially mediates the effect of education on CHD, and the results seems not to be particularly model dependent.