Associations of work hours, job strain, and occupation with endothelial function: the Multi-Ethnic Study of Atherosclerosis (MESA)

Structural and social determinants of health: The multi-ethnic study of atherosclerosis

BACKGROUND

Researchers have increasingly recognized the importance of structural and social determinants of health (SSDOH) as key drivers of a multitude of diseases and health outcomes. The Multi-Ethnic Study of Atherosclerosis (MESA) is an ongoing, longitudinal cohort study of subclinical cardiovascular disease (CVD) that has followed geographically and racially/ethnically diverse participants starting in 2000. Since its inception, MESA has incorporated numerous SSDOH assessments and instruments to study in relation to CVD and aging outcomes. In this paper, we describe the SSDOH data available in MESA, systematically review published papers using MESA that were focused on SSDOH and provide a roadmap for future SSDOH-related studies.

METHODS AND FINDINGS

The study team reviewed all published papers using MESA data (n = 2,125) through January 23, 2023. Two individuals systematically reviewed titles, abstracts, and full text to determine the final number of papers (n = 431) that focused on at least one SSDOH variable as an exposure, outcome, or stratifying/effect modifier variable of main interest (discrepancies resolved by a third individual). Fifty-seven percent of the papers focused on racialized/ethnic groups or other macrosocial/structural factors (e.g., segregation), 16% focused on individual-level inequalities (e.g. income), 14% focused on the built environment (e.g., walking destinations), 10% focused on social context (e.g., neighborhood socioeconomic status), 34% focused on stressors (e.g., discrimination, air pollution), and 4% focused on social support/integration (e.g., social participation). Forty-seven (11%) of the papers combined MESA with other cohorts for cross-cohort comparisons and replication/validation (e.g., validating algorithms).

CONCLUSIONS

Overall, MESA has made significant contributions to the field and the published literature, with 20% of its published papers focused on SSDOH. Future SSDOH studies using MESA would benefit by using recently added instruments/data (e.g., early life educational quality), linking SSDOH to biomarkers to determine underlying causal mechanisms linking SSDOH to CVD and aging outcomes, and by focusing on intersectionality, understudied SSDOH (i.e., social support, social context), and understudied outcomes in relation to SSDOH (i.e., sleep, respiratory health, cognition/dementia).

The impact of long working hours on daily sodium intake

Background

Long working hours are associated with an increased risk of cardiovascular disease, yet the underlying mechanism(s) remain unclear. The study examines how occupational factors like working hours, shift work, and employment status correlate with dietary choices and sodium intake, impacting hypertension risk.

Methods

This study used data from the Korea National Health and Nutrition Examination Survey conducted between 2013 and 2020. The dataset included 8,471 respondents, all of whom were wage workers aged 20 or older and reported working at least 36 hours per week. Individuals who have been previously diagnosed with or are currently diagnosed with hypertension, diabetes, or dyslipidemia were excluded. The average daily sodium intake was assessed via a 24-hour dietary recall method. Average weekly working hours were categorized into 3 groups: 36-40 hours, 41-52 hours, and over 52 hours. Multiple logistic regression models were used.

Results

Study findings revealed that 83.7% of participants exceeded the recommended daily sodium intake of 2 g set by the World Health Organization. After adjusting for confounding factors, a positive correlation was observed between average working hours and daily sodium intake. Among males, statistical significance was found in the group with average weekly working hours of 41-52 hours (prevalence ratio [PR]: 1.17; 95% confidence interval [CI]: 1.05-1.30) and the group exceeding 52 hours (PR: 1.22; 95% CI: 1.09-1.38) when comparing the fourth quartile of daily sodium intake to the combined quartiles of Q1, Q2, and Q3. Among females, no significance was noted.

Conclusions

Long working hours were associated with increased sodium intake, primarily among male workers. This connection is likely attributed to having less time for home-cooked meals, resulting in higher fast food consumption and dining out. A workplace intervention promoting healthy eating and reducing stress is essential to lower sodium consumption and mitigate hypertension risk.

Impact of Acute and Chronic Stress on Thrombosis in Healthy Individuals and Cardiovascular Disease Patients

Psychological stress induces different alterations in the organism in order to maintain homeostasis, including changes in hematopoiesis and hemostasis. In particular, stress-induced hyper activation of the autonomic nervous system and hypothalamic–pituitary–adrenal axis can trigger cellular and molecular alterations in platelets, coagulation factors, endothelial function, redox balance, and sterile inflammatory response. For this reason, mental stress is reported to enhance the risk of cardiovascular disease (CVD). However, contrasting results are often found in the literature considering differences in the response to acute or chronic stress and the health condition of the population analyzed. Since thrombosis is the most common underlying pathology of CVDs, the comprehension of the mechanisms at the basis of the association between stress and this pathology is highly valuable. The aim of this work is to give a comprehensive review of the studies focused on the role of acute and chronic stress in both healthy individuals and CVD patients, focusing on the cellular and molecular mechanisms underlying the relationship between stress and thrombosis.

Chronic stress and endothelial dysfunction: mechanisms, experimental challenges, and the way ahead

Although chronic stress is an important risk factor for cardiovascular diseases (CVD) onset, the underlying mechanisms driving such pathophysiological complications remain relatively unknown. Here, dysregulation of innate stress response systems and the effects of downstream mediators are strongly implicated, with the vascular endothelium emerging as a primary target of excessive glucocorticoid and catecholamine action. Therefore, this review article explores the development of stress-related endothelial dysfunction by focusing on the following: 1) assessing the phenomenon of stress and complexities surrounding this notion, 2) discussing mechanistic links between chronic stress and endothelial dysfunction, and 3) evaluating the utility of various preclinical models currently employed to study mechanisms underlying the onset of stress-mediated complications such as endothelial dysfunction. The data reveal that preclinical models play an important role in our efforts to gain an increased understanding of mechanisms underlying stress-mediated endothelial dysfunction. It is our understanding that this provides a good foundation going forward, and we propose that further efforts should be made to 1) more clearly define the concept of stress and 2) standardize protocols of animal models with specific guidelines to better indicate the mental complications that are simulated.

Current work hours and coronary artery calcification (CAC): The Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Long work hours may be associated with adverse outcomes, including cardiovascular disease. We investigated cross-sectional associations of current work hours with coronary artery calcification (CAC).

METHODS

Participants (n = 3046; 54.6% men) were from the Multi-Ethnic Study of Atherosclerosis. The number of hours worked in all jobs was obtained by questionnaire and CAC from computed tomography. The probability of a positive CAC score was modeled using log-binomial regression. Positive scores were modeled using analysis of covariance and linear regression.

RESULTS

Sixteen percent of the sample worked over 50 hours per week. The overall geometric mean CAC score was 5.2 ± 10.0; 40% had positive scores. In fully-adjusted models, prevalence ratios were less than 40 hours: 1.00 (confidence interval [CI]: 0.88-1.12), 40:(ref), 41 to 49:1.13 (CI: 0.99-1.30), and ≥50:1.07 (CI: 0.94-1.23) and longer current work hours were not associated with higher mean CAC scores (<40:56.0 [CI: 47.3-66.3], 40:57.8 [CI: 45.6-73.3], 41 to 49:59.2 [CI: 45.2-77.6], ≥50:51.2 [CI: 40.5-64.8]; P = .686).

CONCLUSIONS

Current work hours were not independently associated with CAC scores.

Associations between lung and endothelial function in early middle age

BACKGROUND AND OBJECTIVE

Chronic lung disease is associated with impaired endothelial function and this may be a risk factor for poor cardiovascular health. It is unknown if there is an association between lung and endothelial function in the general population. We investigated associations between lung and endothelial function in a population-based cohort of 38-year-old men and women.

METHODS

Systemic endothelial function was measured using peripheral arterial tonometry to calculate the Framingham reactive hyperaemia index. Lung function was assessed using spirometry, plethysmographic lung volumes, airway conductance and gas transfer. Associations between lung and endothelial function were assessed with and without adjustment for potential confounding factors using regression analyses.

RESULTS

Sex modified the association between lung and endothelial function. Among women, lower values of pre- and post-bronchodilator spirometry, total lung capacity and functional residual capacity (FRC) were associated with worse endothelial function (P < 0.05). These associations persisted after adjustment for smoking, asthma diagnoses, fitness and body mass index. Associations were weaker among men: only FRC, airway conductance and post-bronchodilator forced expiratory volume in 1 s (FEV₁ )/forced vital capacity (FVC) ratios were associated with endothelial function. Endothelial function was not associated with gas transfer in either sex.

CONCLUSION

Lower lung volumes and airflow obstruction are associated with endothelial dysfunction among women. There is weaker evidence for an association between airway and endothelial function in men. These findings may partly explain the increased risk of cardiovascular disease among people with poor lung function, but suggest that there are sex differences in this association.

Long Working Hours and Risk of Cardiovascular Disease

Purpose of Review

To summarize the evidence on the relationship between long working hours and cardiovascular disease, such as coronary heart disease and stroke.

Recent Findings

Large-scale meta-analyses with published and individual participant observational data on more than 740,000 men and women free of cardiovascular disease report a link between long working hours (≥ 55 h a week) and the onset of cardiovascular events. Our meta-analytic update of summary evidence suggests a 1.12-fold (95% CI 1.03–1.21) increased risk associated with coronary heart disease and a 1.21-fold (95% CI 1.01–1.45) increased risk of stroke, although the evidence is somewhat inconsistent and the possibility of residual confounding and bias cannot be ruled out. Few studies have examined the mechanisms which may be stress-related, behavioral, or biological. The recent pooled analyses suggest that increased cardiac electric instability and hypercoagulability might play a role.

Summary

The evidence that long working hours are a risk factor for cardiovascular disease is accumulating and suggests a small risk. Studies on the effects of long working hours in high-risk populations and those with pre-existing cardiovascular disease, mechanistic research, and intervention studies are needed to advance this research field.

Women's heart health at mid-life: what is the role of psychosocial stress?

BACKGROUND

Women in mid-life experience unique stressors, including transitions within their family roles, informal caregiving, job stress, and perceived discrimination. The impact of these stressors on cardiovascular health in women during mid-life is of growing interest in both the popular and scientific literature. The objective of this review is to summarize the recent literature on stress and cardiovascular health in mid-life women. We focus on stressors that are relevant to mid-life women, including social stress and discrimination, and long-term risk of CVD events and subclinical CVD measures.

METHODS

We systematically reviewed the literature published between January 2012 and April 2018 for studies examining stress in mid-life and either CVD endpoints or subclinical CVD outcomes. Eligible studies included at least one psychosocial stress exposure, a CVD or subclinical CVD outcome, and either included only female participants, reported sex-stratified analyses or tested for a sex*stress interaction.

RESULTS

We identified 37 studies published since 2012 that met our criteria and included women between the ages of 40 and 65, including 3 case-control studies, 15 cross-sectional studies, and 19 prospective cohort studies. Because clinical CVD events typically occur after age 65 in women, only 22 studies were available that evaluated stress and hard CVD events in samples with mid-life women. Results from these studies suggested an increased and significant risk of CVD due to stress. Of the 15 studies that included subclinical CVD outcomes, the majority showed that mid-life women experiencing greater levels of stress had more subclinical CVD, as indicated by carotid intima-media thickness, flow-mediated dilation and arterial stiffness; however, several studies reported null associations.

CONCLUSIONS

General life stress, including perceived stress and life events, in mid-life was significantly related to later-life CVD risk and mid-life subclinical CVD in the majority of studies published in the past six years. Job stress was inconsistently related to CVD risk in women, and fewer studies examined characteristics of other social roles, such as marriage, motherhood or caregiving. Perceived discrimination also was associated with CVD events and subclinical CVD in some samples of mid-life women. Further investigation into specific stressors relevant to women in mid-life, including caregiving and marital stress, are needed to understand the full extent to which life stress impacts CVD risk in mid-life women.

Chronic Stress and Endothelial Dysfunction: The Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Endothelial dysfunction may represent an important link between chronic stress and cardiovascular disease (CVD) risk. However, few studies have examined the impact of chronic stress on endothelial dysfunction. The purpose of this study was to examine whether chronic stress was associated with flow-mediated dilation (FMD) and 2 biomarkers of endothelial dysfunction (intercellular adhesion molecule-1 (ICAM-1) and E-selectin) in a multiethnic sample of adults (ages 45-84 years).

METHODS

Data come from the baseline examination of Multi-Ethnic Study of Atherosclerosis participants. Chronic stress was assessed based on self-report of the presence and severity of ongoing problems in 5 domains. FMD was obtained using high-resolution ultrasound; biomarkers were assayed in different subsets of participants.

RESULTS

Higher chronic stress was associated with lower absolute FMD (mm FMD) in models adjusted for demographic and socioeconomic characteristics (0.169mm in high-stress participants vs. 0.178 and 0.179mm in medium and low-stress participants; P for trend = 0.04). This association remained unchanged with further adjustment for behavioral and biological CVD risk factors. Higher stress was related to higher ICAM-1 in models adjusted for sociodemographic characteristics and biological risk factors (P for trend = 0.005), but this association attenuated with adjustment for cigarette smoking (P for trend = 0.07). Chronic stress was not associated with E-selectin.

CONCLUSIONS

Our findings suggest chronic stress is related to endothelial dysfunction, possibly in part through other stress-associated CVD risk factors such as cigarette smoking.