Summary
Besides the ‘classic’ cardiovascular risk factors (high blood pressure, dyslipidaemia, metabolic syndrome and diabetes), the work environment is playing an increasingly significant role in cardiovascular morbidity and mortality. Several elements contribute to the effect of the work environment: physical factors, chemical factors, shift work and psychosocial factors. The effects of psychosocial factors on the aetiology and progression of cardiovascular disease have been confirmed by several studies. Identification of these work-related psychosocial factors must be taken into account when evaluating cardiovascular risk factors, in order to ensure better prevention.
Résumé
À côté des facteurs de risque cardiovasculaires « classiques » (hypertension artérielle, dyslipidémie, syndrome métabolique, diabète), l’environnement professionnel joue un rôle de plus en plus important dans la morbidité et la mortalité cardiovasculaire. Plusieurs éléments contribuent à l’action de l’environnement professionnel : les facteurs physiques, les facteurs chimiques, le travail posté et les facteurs psychosociaux. Les effets des facteurs psychosociaux sur l’étiologie et la progression des maladies cardiovasculaires sont étayés par de nombreux travaux. L’identification de ces facteurs psychosociaux au travail doit être pris en compte lors de l’évaluation des facteurs de risque cardiovasculaires afin d’assurer une meilleure prévention.
Introduction
There has been a significant increase in the incidence of CVDs in industrialized countries over the last 40 years. CVD was the leading cause of mortality until the turn of the 21st century, when deaths caused by tumours surpassed deaths caused by CVD in France. The ranking of causes differs markedly according to sex, as CVD is the second cause of mortality in men after tumours, whereas this order is reversed for women . Recent developments in the monitoring of ischaemic heart disease have revealed two trends: a drop in cardiovascular mortality , particularly a decrease in deaths caused by acute coronary syndrome, which reflects progress made in medical case management; and a slowing down or even stabilizing of the decline in the incidence of coronary disease, which indicates that efforts are required in terms of primary prevention .
Three major groups of determinants are usually identified for cardiovascular morbidity and mortality: personal determinants (age, sex); biological determinants; and behavioural determinants. In France, primary prevention mainly focuses on the ‘classic’ risk factors, i.e. bioclinical and behavioural determinants . These factors are, primarily, high BP, dyslipidaemia, smoking, diabetes and metabolic syndrome. This approach to prevention needs to be supplemented for several reasons.
First of all, according to various studies , these ‘classic’ factors can explain 50 to 80% of cases of CVDs. The INTERHEART study, which measured the association of nine modifiable risk factors with myocardial infarction in 52 countries, revealed that PSFs (stress at home or at work, financial stress, life events) accounted for 32.5% of the population attributable risk for myocardial infarction, putting them in third place behind risks associated with lipids and cigarette smoking . This means that proper management of the PSFs in primary prevention could, in theory, reduce the number of infarctions by 32%.
Secondly, prevention that focuses on the ‘classic’ factors facilitates the individual approach, centred on the use of risk prediction charts. These charts are used to calculate the cardiovascular risk of an individual, by identifying the level or presence of a number of ‘classic’ risk factors. This method is an appealing concept; the approach focuses on bioclinical or behavioural factors, without taking into account other risk factors and psychosocial determinants, in particular. Modelling becomes approximate as soon as the person does not belong to the reference group used to develop the risk prediction equation. These charts have trouble predicting the overall cardiovascular risk .
Lastly, analysis of premature mortality (prior to age 65 years) caused by CVD reveals disparities in the level of reduction between the different social groups. There is still a higher rate of cardiovascular mortality among groups with a lower socioeconomic status or among individuals with a lower level of education . This disparity clearly raises the question of the role of socioprofessional determinants in health inequalities.
For all of these reasons, the long-debated role of PSFs in the onset of CVD is now clearly established. Several studies in literature have considered both the emotional impact and the quality of life impact on cardiovascular health. The stress factors associated with cardiovascular risk include the following: type A behaviour (stress hyperactive individuals with a strong sense of competitiveness) ; type D behaviour (negative affectivity and inhibited relationships) ; anxiety disorders (panic disorders, anxiety) ; and mood disorders . On the other hand, some other factors, such as social support, are regarded as more protective. More specifically, our article will deal with the role of PSFs at work. Numerous factors linked with occupational exposure have been identified. A great number of published studies have evaluated the role and mode of action of work-related PSFs on cardiovascular morbidity and mortality. There is such a large number and variety of such studies , in fact, that it is impossible to present a complete bibliography of them. The principal aim of this article is to review the main achievements in this area. First, we will discuss the theoretical approaches and the development of the main tools used to evaluate PSFs in the workplace, and then we will endeavour to reveal the major trends in the cardiovascular field, illustrating these with a selection of results.
Methods
We searched through several Medline databases, using keywords such as ‘psychosocial factors’, ‘ischaemic heart disease’, ‘stress at work’, ‘job strain’ and ‘arterial hypertension (AHT)’. We examined the articles published between 1979 (the year Karasek’s first article was published) and 2008. The articles selected refer explicitly to Karasek’s model and Siegrist’s model, and discuss cardiovascular morbidity and mortality linked to AHT and ischaemic heart disease. We restricted ourselves to epidemiological studies published in peer-reviewed journals. We selected the standard reference works or those that have been cited very often.
Psychosocial factors at work
Over the last few years, jobs have been characterized by an overall reduction in strenuous physical activity–although this reduction is only slight among the exposed groups–and increasing job demands . These PSFs at work are linked to the individual, collective and organizational aspects of the occupational activity. They are likely to have an effect on health and, in particular, they include psychological job demands (excessive workloads, time pressure, ambiguous roles and workplace insecurity) and poor labour-management relations. The quantification of exposure to job strain has been evaluated by several theoretical models. The two most commonly used general models are the Karasek model and the Siegrist model . Other more recent concepts have been developed, relating to organizational justice or violence in the workplace. We will restrict ourselves to the Karasek and Siegrist models, which are the subject of the highest number of studies.
The PSF evaluation model, put forward by Karasek, is based on a self-report questionnaire that evaluates an individual’s perception of work through several dimensions: the first dimension is psychological demand and focuses on the psychological stress associated with task complexity and execution, time pressure, work interruptions, unplanned tasks and contradictory demands. The second dimension is decision latitude, which measures the amount of control an individual has over their own work (freedom to choose how to carry out the work) and skill use (the possibility of using one’s qualifications and developing new ones). Individuals are positioned based on these two dimensions, using an algorithm to categorize them into one of four groups ( Fig. 1 ): the high demand, low decision latitude combination is labelled a high-strain job; the high demand, high decision latitude combination is labelled an active job; the low demand, low decision latitude combination is labelled a passive job; and the low demand, high decision latitude (ideal situation) is labelled a low-strain job. To these two dimensions, a third has been added to evaluate relationships between coworkers and superiors (social support in the workplace) . The underlying hypothesis is that the high psychological demand and low decision latitude combination, categorized as job strain, increases the risk of CVD, especially where there is little social support.
The effort-reward imbalance model was introduced later by Siegrist. This model distinguishes two sources of effort and three types of reward ( Table 1 ). It defines and analyses the socioemotional risks in the work environment in terms of the mismatch between the efforts invested and the rewards–whether symbolic (esteem, recognition) or pecuniary–because the efforts are part of a process in which the rewards are expected. It is based on the hypothesis that significant and continued efforts and low rewards can have a damaging effect on health. In the Karasek model, the decision latitude dimension is pivotal, whereas in the Siegrist model, it is the concept of social reciprocity (the right to legitimately expected rewards) that is the central tenet. These two models have been extensively validated by studies on the incidence of CVD .
| Extrinsic efforts |
| Time pressure |
| Interruptions |
| Responsibilities |
| Pressure to work overtime |
| Physical loads |
| Increasing demands |
| Intrinsic efforts |
| Need for approval |
| Competitiveness and latent hostility |
| Impatience and disproportionate irritability |
| Inability to withdraw from work |
| Rewards |
| Monetary gratification |
| Salary |
| Esteem |
| Respect and esteem |
| Adequate support |
| Unfair treatment |
| Status control |
| Promotion prospects |
| Undesirable change in the work situation |
| Job insecurity |
| Inadequate job status |
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