Psychological job demands increase the risk of ischaemic heart disease: a 14-year cohort study of employed Danish men

Aims To test the relationship between job strain and the incidence of ischaemic heart disease (IHD) prospectively in the Danish working population. Methods and results In 1986, a clinical examination was undertaken of 659 men, all employed and without known IHD, together with a questionnaire-based evaluation of living conditions and psychosocial factors at work, including items identified in the job strain model. This study was part of the World Health Organization-initiated MONICA II study. In the job strain model, job strain is defined as the combination of high psychological demands and a low degree of control in the work situation. An objective classification of the components in the job strain model was made by imputation by utilizing the participants’ job title and the principles guiding the payment of their salaries/wages. In addition, a questionnaire-based subjective classification was undertaken. All participants were followed until the end of 1999 with regard to hospitalization and death as a result of IHD. Stepwise analyses were made, adjusting for age, social class, social network and established behavioural and physiological coronary risk factors. Self-reported job strain was significantly associated with IHD independently of standard coronary risk factors. Of the two components in the job strain model only high demands contributed significantly to this result. The study did not support the job strain hypothesis when an imputed, objective classification of the components in the job strain model was applied. This is in accordance with the majority of other studies in this area. An unexpected finding was that the incidence of IHD was highest among employers and managers. Conclusion High psychological demands at work are a risk factor for IHD, a fact that should affect the primary and secondary prevention of IHD.