INCREASING DIFFERENCES IN MYOCARDIAL-INFARCTION INCIDENCE BETWEEN SOCIOECONOMIC GROUPS IN STOCKHOLM

During the 1980s the incidence of myocardial infarction declined in St ockholm. From the point of view of public health and prevention, it is important to study this decline in different population subgroups. Th e aim of the present study was to investigate differences in the incid ence of myocardial infarction among socio-economic groups in Stockholm county from 1976-84 and to evaluate whether these differences changed during the study period. The study was carried out by means of case-c ontrol methods. In all, 28029 cases were identified in the study base and 77% of these were classified as first events. For each case two co ntrols were randomly selected front the study population, stratified b y sex, age, and calendar year. Information from the 1970 census was us ed to classify cases and controls with regard to socio-economic group. Compared with higher non-manual employees, unskilled manual workers h ad a 60% greater incidence of myocardial infarction for men. For women the corresponding difference was 120%. During the study period the di fference in incidence between manual workers and non-manual employees increased rapidly for men. This indicates that the decline in myocardi al infarction incidence seen in Stockholm county during the 1980s, inv olved manual workers to a smaller extent than non-manual employees. Th e causes of these diverging trends are not known. A variety of factors may have contributed, including life-style factors such as smoking, d ietary factors, and physical activity as well as work environment fact ors. An improved understanding of the differences among socio-economic groups with regard to myocardial infarction incidence trends could mo st likely contribute to a more effective prevention.