People with stressful jobs and little power to make decisions face higher risks for heart disease than their peers with less job strain, a European review suggests.
Job strain, the combination of high job demands and low control at work, has been associated with coronary heart disease in previous studies, but the new review defines the risk more precisely.
"Our findings suggest that job strain is associated with a small, but consistent, increased risk of an incident event of cardiovascular heart disease," Mika Kivimaki from University College London and her co-authors concluded in Thursday's online issue of the Lancet.
"Prevention of workplace stress might decrease disease incidence; however this strategy would have a much smaller effect than would tackling of standard risk factors, such as smoking."
In the study, 15 per cent of the 197, 473 participants reported job strain. Their average age when the study began was 42.
The researchers recorded 2,358 incidents of coronary heart disease.
The researchers estimated the heart risk of job strain was 1.23 times higher for job strain than no job strain, after taking age and sex into account in the analysis.
Recognizing that subclinical coronary heart disease itself can affect levels of stress, the researchers excluded heart attacks and similar events that occurred at the start of the study period.
Stress on and off the job
Factors like socioeconomic status, tobacco smoking, alcohol intake, physical activity levels were also considered.
Since the researchers used non-randomized observational data, they couldn't draw any conclusions about cause-and-effect.
They estimated that 3.4 per cent of the coronary events could be attributed to job strain, which they called "a notable proportion of coronary heart disease events in working populations."
In comparison, standard risk factors such as smoking account for 36 per cent, abdominal obesity for 20 per cent and physical inactivity 12 per cent, previous research suggests.
Other sources of stress, such as organizational downsizing, death of a child, and caring for a sick spouse at home, might also be associated with a higher risk of coronary heart disease, the researchers said.
The findings support the idea that a harmful psychological load often results from a combination of high demands and low job control, rather than either of those factors alone, Bo Netterstrom from the department of occupational and environmental medicine, Bispebjerg Hospital in Copehagen said in a journal comment published with the study.
Job insecurity and factors related to social capital and motions are likely to be important in the future, particularly in the current economic crisis, Netterstrom said.