Largely on the basis of studies in middle aged men (table ), four groups of psychosocial factors were identified by using the predefined quality filter: psychological traits (type A behaviour, hostility), psychological states (depression, anxiety), psychological interaction with the organisation of work (job control-demands-support), and social networks and social support. In simple terms this corresponds to a spectrum with mainly psychological components at one end and a stronger social component at the other. The box summarises the key results.
Studies showing role of psychosocial factors
In healthy populations, prospective cohort studies suggest a possible aetiological role for:
- Type A/hostility (6/14 studies)
- Depression and anxiety (11/11 studies)
- Psychosocial work characteristics (6/10 studies)
- Social support (5/8 studies)
In coronary heart disease patient populations, prospective studies suggest a prognostic role for:
- Type A/hostility (0/5 studies)
- Depression and anxiety (6/6 studies)
- Psychosocial work characteristics (1/2 studies)
- Social support (9/10 studies)
Although this review cannot discount the possibility of publication bias, prospective cohort studies provide strong evidence that psychosocial factors, particularly depression and social support, are independent aetiological and prognostic factors for coronary heart disease.
Studies of type A behaviour, hostility, and coronary heart disease. References in this table are given on the BMJ website
Hostility and type A behaviour
Type A behaviour pattern—the only personality trait which met the criteria of our review—is characterised by hard driving and competitive behaviour, a potential for hostility, pronounced impatience, and vigorous speech stylistics. The instruments for measurement of type A behaviour and hostility—the Jenkins activity scale, the structured interview, the Minnesota multiphasic personality inventory (MMPI), the Bortner hostility scale—have been subjected to psychometric testing and incorporated into many cardiovascular cohort studies, including some that have not reported results. Unlike other psychosocial factors, type A is distinguished by being the subject of numerous intervention trials.17
On the basis of early positive findings in the Framingham study18
and the Western Collaborative Group’s eight year follow up,19
among other evidence, the National Institutes of Health declared type A an independent risk factor for coronary heart disease. However, with the publication of negative findings20–22
it was proposed that a more specific component of type A, namely hostility, might be aetiological, although there are conflicting studies. None of the five studies that examined type A or hostility in relation to prognosis among patients with coronary heart disease showed an increased risk; indeed, one suggested a protective effect.
Depression and anxiety
The relation between depression and anxiety and coronary heart disease differs from those of other psychosocial factors for several reasons. Firstly, unlike other psychosocial factors, depression and anxiety represent well defined psychiatric disorders, with standardised instruments for measurement. Secondly, depression and anxiety are commonly the consequence of coronary heart disease, and the extent to which they are also the cause poses important methodological issues. Thirdly, the ability to diagnose and treat such disorders makes them attractive points for intervention. Finally, depression and coronary heart disease could share common antecedents—for example, environmental stressors and social supports.
Table shows the results from the 11 prospective studies that investigated depression or anxiety in the aetiology of coronary heart disease, all of which were positive. All three of the prospective studies examining the effect of anxiety in the aetiology of coronary heart disease had positive results. Intriguingly, there is some evidence that this effect is strongest specifically for phobic anxiety and sudden cardiac death. Wassertheil-Smoller23
reported the effect of depression in relation to cardiovascular events among 4367 healthy older people. An increase in depression symptoms (but not the baseline scores) predicted events, even when multiple covariates were controlled for. Such findings are compatible with the hypothesis that premonitory signs of coronary heart disease such as angina or breathlessness may have led to the increase in depression. Studies with longer periods of follow up are less likely to be confounded by the possibility of early disease causing depression, but raise further questions about the time course of exposure. For example, it is possible that there is a common trigger (such as viral illness) that precipitates both symptoms of depression and atherothrombotic processes. By examination of subclinical manifestations of coronary heart disease (using non-invasive measures of arterial structure and function, for example) before the onset of symptoms, the temporal sequence of the relation might be better understood.
Studies of depression and anxiety and coronary heart disease. References in the table are given on the BMJ website
Depression in patients after myocardial infarction seems to be of prognostic importance beyond the severity of coronary artery disease. Although discrete major depressive episodes are not uncommon after a myocardial infarction, depressive symptoms are more prevalent. Given the graded relation between depression scores and risk, the long lasting nature of the effect, and the stability of the depression measured across time, it has been proposed that depression is a continuously distributed chronic psychological characteristic.
Psychosocial work characteristics
The longstanding observation that rates of coronary heart disease vary markedly among occupations—more than can be accounted for by conventional risk factors for coronary heart disease—has generated a quest for specific components of work that might be of aetiological importance. The dominant “job strain” model of psychosocial work characteristics, as proposed by Karasek and Theorell, grew out of secondary analyses of existing survey data on the labour force. This model proposes that people in jobs characterised by low control over work and high conflicting demands might be high strain. A subsequent addition to the model was that social support might buffer this effect. The advantage of the model is that it generates specific hypotheses for testing.
Table shows prospective cohort studies that have examined the relation between job strain and coronary heart disease. Both self reports and ecological measurements (assigning a score on the basis of job title) of job strain have been made. Self reports may be biased by early manifestations of disease, and ecological measurements may lack precision. The finding that these methods tend to give reasonably consistent results suggests that they are complementary. Six of the 10 studies were had positive results. There is growing emphasis on the importance of low job control rather than on conflicting demands,24
and it seems likely that these empirical results will lead to a reformulation of the model. Alternative models of psychosocial work characteristics involve an imbalance between the effort at work and rewards received.25,26
Studies of psychosocial work characteristics and coronary heart disease. References in table are given on BMJ website
Social network structure and quality of social support
Social supports and networks relate to both the number of a person’s social contacts and their quality (including emotional support and confiding support). Marital status—information routinely sought in clinical practice—is a simple measure of social support, and the ability of low social support to predict all cause mortality has long been recognised. It has been proposed that social supports may act to buffer the effect of various environmental stressors and hence increase susceptibility to disease,27
but most of the evidence supports a direct role.
Five of the eight prospective cohort studies that investigated aspects of social support in relation to the incidence of coronary heart disease were positive (table ). Nine of the 10 prognostic studies were positive, and the relative risks for three of these studies exceeded 3. Despite the strength and consistency of these findings, the relative effect of structural and functional aspects of social supports has yet to be delineated.
Studies of social networks and social supports and coronary heart disease. References in table are given on BMJ website