Differences in the incidence of myocardial infarction among occupational groups.

An inverse relationship between social class and coronary heart disease has been observed in several countries, but few studies have investigated the incidence of this disease over different occupational groups. A case-referent study was carried out to estimate the relative risk of a first myocardial infarction in various occupational groups. Cases of myocardial infarction (N = 36,602) were identified from both hospital discharge and death records. Two referents for each case were randomly selected from the study base. Information about occupation was obtained from two consecutive censuses. An increased incidence, compared with that of others employed, was found for persons in some occupations in production work, transport work (men), and service work (women). Low relative risk were found mainly for persons in occupations demanding a high education. The relative risks ranged from 0.3 to 2.8. Several factors, occupational as well as nonoccupational, may be of importance in explaining the findings.