The self-employed and the self-driven: two coronary-prone subpopulations from the Zeist study

In four Dutch communities, Zeist, De Bilt, Driebergen, and Doorn (total population, 111,000 inhabitants), all patients who suffered acute coronary events between July 1970 and March 1974 were recorded. By combining data from this study with data from the 1971 national census of the Netherlands, it was possible to demonstrate that the incidence of acute coronary events is twice as high for self-employed men as for employed men and as much as seven times as high for self-employed women as for housewives. The incidence of acute coronary events is practically the same for self-employed women aged 45-69 years as for men of the same age in the general population. Men aged 35-64 years whose nature is such that they feel driven to do all their work with great intensity and against the clock ("self-driven men") suffer myocardial infarction seven times as frequently as others and are 2.4 times as likely to die of fatal coronary attack. Only 10% of the self-employed male referents, but 50% of the self-employed male cases, consider themselves self-driven. On the other hand, experiences of excessive working hours and time pressures are not related to the incidence of acute coronary events. These results were not influenced by and were independent of other known risk indicators.