Low job control and myocardial infarction risk

Many studies have shown an association between low job control and increased risk of myocardial infarction. Some have emphasised the importance of the combination of high psychological demand and low control (job strain) but in other studies only low control and not job strain, has seemed the important factor. Researchers in Lithuania have again found low job control to be more important than job strain and to be operative throughout all occupational categories.

They performed a case-control study with 203 cases and 287 controls. Cases were men aged 25–64 years who had survived a first myocardial infarction between 1 October 2000 and 30 September 2002. Controls were men without evidence of coronary disease matched with cases for age and living in the same 12 districts of the city of Kaunas. Cases and controls were interviewed at their local hospitals by doctors who used a standardised questionnaire. Psychosocial job demands and job control were assessed using the scoring system of the Swedish version of the Karasek demand-control questionnaire. Median scores for job demands and job control were 11 and 14 respectively and scores above and below these levels were classified as high and low. Occupations were categorised according to the International Standard Classification of Occupations, (10 categories, 0–9).

The risk of myocardial infarction was greatest in occupational categories 1 (legislators, senior officials, and managers) and 8 (plant and machine operators and assemblers) who had a 93% and a 58% increase in risk compared with the lowest risk group (category 7, craft and related trades workers). Adjustment for conventional coronary risk factors did not change these findings. Scores for job demands and job strain (ratio of job demands to job control) were similar in cases and controls. Low scores for job control, however, were associated with a more than two fold increase in risk of myocardial infarction and the effect was similar (odds ratios (ORs) 2.23–2.78) throughout all occupational categories.

In prosperous western countries high risk of coronary disease is related to high job strain and low social position. In a transitional country of the former Soviet bloc low job control seems more important than job strain and operates throughout the social scale and through all occupational categories.