MYOCARDIAL-INFARCTION AMONG MALE BUS, TAXI, AND LORRY DRIVERS IN MIDDLE SWEDEN

Objectives-The aim of the present case referent study was to investiga te the incidence of myocardial infarction among male professional driv ers, taking the type of vehicles and area of residence into account. M ethods-The study base comprised all men aged 30-74 in five counties in middle during 1976-81 or 1976-84. cases of the first episode of myoca rdial infarction were identified from registers of hospital admissions and causes of deaths. Referents were selected randomly from the study base. Information about occupation was obtained from the national cen suses in 1970 and 1975. The possible impact from tobacco smoking and o verweight were evaluated by simulations in combination with indirect d ata on these factors. Results-The incidence of myocardial infarction w as increased among bus drivers in Stockholm (relative risk (RR) = 1.53 , 95% confidence interval (95% CI) 1.15-2.05), and among taxi drivers both in Stockholm (RR 1.65, 95% CI 1.30-2.11) and in the surrounding r ural counties (RR 1.82, 95% CI 1.17-2.82). A smaller increase was foun d among long distance lorry drivers, whereas the relative risk among s hort distance lorry drivers was close to unity. Indirect comparisons m ake it unlikely that the excess among bus drivers in Stockholm could b e explained by uncontrolled confounding from tobacco smoking or overwe ight. A very high proportion (more than 80%) of urban bus drivers in S weden report a combination of high psychological demands and low contr ol at work. Conclusions-Different types of drivers are at different ri sk of myocardial infarction. Bus drivers in urban areas seem to be at an increased risk, which is unlikely to be explained by uncontrolled c onfounding from tobacco smoking or overweight. Psychosocial work condi tions may play a part in the increased incidence of myocardial infarct ion among urban bus drivers and should be investigated further.