Stress, and its role in illness - II

Reference 3 involves British civil servants, approximately two-thirds of them male. The study involved 10,308 workers with a followup time of 5 years. Workers' degree of control over their work was evaluated both by self assessment questionnaires, and by supervisor reporting. The results of the study show that subjects with low job control throughout the study had a relative risk of 1.93 (1.34 to 2.77 Margin of Error) to coronary heart disease compared to subjects who had high job control throughout. (In this study, CHD includes angina). When we look at the results for diagnosed ischemic heart disease, the risk ratio is reduced to 1.26 (0.67 to 2.39 Margin of Error), that is not particularly significant. Never the less, the authors conclude that "low control in the work environment is associated with an increased risk of coronary heart disease ... in government offices".

The study described in reference 4 examins the progression of atherosclerosis in the carotid artery (the carotid artery is the main artery that supplies blood to the head). Two causes are analyzed: the effect of workplace demands, and changes in blood pressure induced by stress. The study takes place in eastern Finland, involving 591 men aged 42 to 60, and involved measurements of their artery thickness. They find that men who showed stress-induced blood pressure increase, and who reported the highest job demands, also experienced the largest increase in artery wall size and plaque. This type of buildup is a known precursor to coronary heart disease.

The study in reference 5 considers Japanese workers. 195 men aged 30 to 69 admitted to hospital with acute myocardial infaction were compared to a control group of 331 men with matched age and occupation judged to be free of CHD. They found that men working more than 11 hours a day have an increased risk of 2.4 (1.3 to 4.7 Margin of Error) compared to men who work 7 to 9 hours a day. Men who work less than 7 hours a day also have an increased risk of 3.1 (1.8 to 5.3 Margin of Error). Is it possible that the stress associated with insufficient work is also a cause of heart disease...?