Research Findings linking Workplace Factors to Cardiovascular Disease Outcomes – CHAPTER 2

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Occupational Medicine: State of the Art Reviews; Chapter 2: Research Findings Linking Workplace Factors to CVD Outcomes Authors: Paul Landsbergis, Kyle Steenland, Lawrence Fine, Karen Belkic, Peter Schnall, Dean Baker, Tores Theorell, Johannes Siegrist, Richard Peter, Robert Karasek, Michael Marmot, Chantal Brisson, Finn Tuchsen

Abstract

A variety of workplace conditions have been implicated as risk factors for cardiovascular disease (CVD). These include shift work, long work hours, and chemical (e.g., carbon disulfide, nitrate esters, carbon monoxide, methylene chloride, solvents), physical (e.g., cold, heat, noise, passive smoking, sedentary work) and psychosocial conditions. The most consistent evidence is provided by sources of psychosocial stress at work. The evidence strongly suggests a causal association between job strain (a combination of high psychological demands and low job decision latitude, or low job control) and hypertension and CVD. Low decision latitude is also a risk factor for CVD. As yet limited but convincing evidence exists for a role of another psychosocial factor effort-reward imbalance (ERI) with similar observed effect sizes as job strain. In addition, threat-avoidant vigilant work (TAV) has been identified through studies of single occupations as a potentially helpful explanatory variable as to why groups such as professional drivers — whose work is characterized by high TAV, — have the most consistent evidence of elevated risk of CVD and hypertension.

Stressors At The Workplace: Theoretical Models – CHAPTER 3

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Abstract

Several theoretical models of workplace psychosocial stressors have been empirically validated, including the Demand-Control-Support (DCS) model and the Effort Reward Imbalance (ERI) model. The nature of these models –deeply rooted in social class relations–is explored in terms of their relationship to the organization of work. While gradations in degree of job strain (high demand, low control work) exist, the trend is for increasing demands with inadequate augmentation of control for more and more of the labor force. Demands are viewed in a broad context encompassing workload, time pressure, conflicts, requirements upon attentional resources, and the emotional dimensions of work-especially those involving threat avoidance–as well as long and unphysiologic work hours. In comparison to the DCS model with its emphasis on moment-to-moment control over the work process (i.e. decision latitude), the ERI model emphasizes macro-level rewards such as career opportunities, job security, esteem and income. The ERI model also integrates the exigencies and rewards of the job with the individual’s input and coping style. The insights provided by cognitive ergonomics and brain research complement the DCS and ERI models, and can be of practical use in efforts to humanize the labor process. The concept of total burden (risk) due to exposure to multiple occupational stressors is explored.

The Central Nervous System: Bridge between the External Milieu and the Cardiovascular System – CHAPTER 4

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Abstract

The concept of neurocardiology, introduced as an interdisciplinary area linking the neurosciences and cardiology, is expanded into a tripartite construct, which includes the environment as the potential stressor: “econeurocardiology”. Experimental animal studies provide empirical grounding for this construct; therein central stress mechanisms are implicated in cardiac electrical instability, as well as in hypertension, abnormalities of heart beat dynamics and atherogenesis. The defense response appears to play an important role in these processes, with the defeat reaction being activated in chronic stress, especially of a severe nature. In the worst case, both are operative: the defense-defeat response, activating the sympatho-adrenomedullary and hypophyseal-adrenocortical pathways, respectively. This appears to be a particularly deleterious combination for the cardiovascular system.

Evidence for Mediating Econeurocardiologic Mechanisms – CHAPTER 5

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Abstract

Workplace factors can impact upon many pathways leading to CVD, promoting underlying pathological processes, as well as triggering acute cardiac events. Neuroendocrine and autonomic mechanisms are the main mediators. Elevated catecholamines and cortisol have been demonstrated in relation to occupational stressors. Exposure to job strain has been directly linked to increased workplace ambulatory blood pressure (AmBP) and hypertension. The connection among chronic exposure to job strain, high workplace AmBP and increased left ventricular mass has also been empirically confirmed. Experimental data implicate stress mechanisms at several steps in the early and late stages of atherogenesis, with corroborative occupational epidemiologic evidence for some of these processes. Patterns consistent with the Cardiovascular Metabolic Syndrome have been reported in association with Effort-Reward Imbalance. In coronary patients laboratory mental stress can provoke myocardial ischemia, the biological determinants of which are frequently work-related. However, work-place field studies of myocardial ischemia are lacking. Stress mechanisms can also compromise cardiac electrical stability; several indicators of which can now be monitored during work. Circadian and septadian data suggest that workplace factors could precipitate myocardial infarction and sudden cardiac death at vulnerable time intervals in at-risk individuals.

Measurement of Psychosocial Workplace Exposure Variables – CHAPTER 6

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Abstract

An important empirical and methodologic issue is the determination whether it is primarily the objective characteristics of jobs or an individual’s subjective perception and evaluation of them (or some combination of these) that is most predictive of changes in blood pressure and the development of cvd. This chapter describes three main approaches for measurement of job characteristics: self-report questionnaires (e.g., Job Content Questionnaire, Effort-Reward Imbalance questionnaire, Occupational Stress Index); imputation of job characteristics scores based on aggregate data (e.g. national job title averages); and external assessment (e.g. supervisor or coworker ratings, job analysis by expert observers). Use of multiple methods of assessment of job characteristics allows for triangulation. We review important research results, highlight advantages and limitations of each method and discuss some issues to be resolved through future research. We recommend multi-method strategies, for convergent validation, using as many of these approaches as possible.

Assessment of the Cardiovascular System at the Workplace – CHAPTER 7

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Abstract

The obstacles and challenges of obtaining a cardiovascular disease history at the workplace are explored including the use and limitations of symptom data, the issue of false negatives and false positives, as well as the need for caution to avoid bias if symptoms are reported together with the self-report about exposure. A discussion of the various techniques of blood pressure (bp) measurement at the workplace is presented, including casual, self-measured, and ambulatory monitoring, their advantages and limitations, and their particular utility for the workplace. A new protocol for obtaining point estimates of bp at the worksite is outlined and its feasibility as an alternative to traditional measures of casual bp or ambulatory bp monitoring is assessed. In addition, other clinically-relevant endpoints which are sensitive, stress-mediated and measurable by ambulatory electrocardiographic monitoring are described.

Cardiovascular Evaluation of the Worker and Workplace: A Practical Guide for Clinicians – CHAPTER 8

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Unlike several other branches of medicine, (e.g., pulmonology), primary cardiology has yet to fully develop a discipline of occupational cardiology. The authors outline an approach for including a focused occupational history in the CV work-up and present a graded, risk-stratified algorithm for occupational cardiologic assessment. This work-up can help clinicians make specific recommendations concerning working conditions, as these impact upon the patient’s CV status.

Clinical Issues: Return to Work and Public Safety – CHAPTER 9

by Regis de Gaudemaris

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Return to work after cardiac events is an especially delicate question for the clinician. The cardiologic caregiver must evaluate the full clinical picture, including symptoms and morphological and functional status, as well as address complex personal, psychological, social, economic, legal, and ethical issues. The importance of job characteristics is illustrated by the existing, albeit limited, longitudinal data showing that return to high-strain work is a significant independent predictor of mortality in young men post-myocardial infarction.

Screening and Management of the Workplace for CVD Risk – CHAPTER 10

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Abstract

Practical information is provided for clinicians who may be called upon to evaluate and manage the workplace as a potential source of increased risk for cardiovascular disease (CVD). The possibilities and limitations of stress management programs focusing on the individual, as well as the need for complementary organizational job redesign approaches, are presented. We raise the question: could lowering of job strain be a specific therapeutic modality for workplace-related hypertension, and we view this in light of the efficacy of pharmacologic, as well as other individual-based approaches to managing elevated blood pressure. Guidelines for the clinician to help determine the effectiveness of work-based intervention trials focused upon CVD prevention and to define critical endpoints for various clinical groups, are discussed, together with some clinical-methodological caveats for interpretation of findings. Finally, an argument is presented that a public health perspective is needed to effectively tackle work-related CVD, with incorporation of the concept of “occupational sentinal health event” into the realm of cardiology. As the role and potential contribution of the clinician in this process become better defined, possibilities emerge for him or her to become a truly effective agent for change, in improving the work environment.

Costs of Occupational Circulatory Disease – CHAPTER 11

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This chapter analyzes the overt and hidden economic costs of work-related cardiovascular diseases. Affected individuals and society at large, rather than employers, pay much of the costs. Economic interventions to motivate public health approaches to preventing CVD are explored.