Men who worked for 25 years or more at a demanding job over which they felt little control had a large increase in blood pressure both when they were on the job and at home, according to the study published in the American Journal of Epidemiology.

A previous study, by the same researchers, showed that men who were currently in high stress jobs had an increase of 6 to 8 points in systolic blood pressure -- the upper number in the blood pressure reading -- compared to workers in low stress jobs.

One question the previous study hadn't answered was whether job stress over many years would have a cumulative effect, Dr. Paul Landsbergis, an assistant professor in the department of community and preventive medicine at the Mount Sinai School of Medicine in New York, said in an interview with Reuters Health.

"We wondered: what about all those years before they came to this study?" Landsbergis said. "The men were 30 to 60 years old when the study started so some had already had many years on the job."

When Landsbergis and his colleagues took a closer look at previous job experience, they found that 25 or more years in a highly demanding, low-control job led to an extra 4.8 point rise in systolic blood pressure when the men were at work and 7.9 point rise when the men were at home.

For the new study, Landsbergis and his colleagues interviewed 213 men about their job histories. The impact of current working conditions had already been studied in these men in a trial called the Work Site Blood Pressure Study.

The men were asked about characteristics of their jobs. For example, to determine how much control the men had over their work environment, men were asked about how much freedom they had to make decisions and whether they
could choose how to perform their work. Researchers also tried to determine how demanding the job was and how pressured the men felt by their jobs.

Landsbergis says he hopes that studies like this will encourage employers to try to find ways to make jobs less stressful.

"There are lots of ways," he said. "Workers can be allowed to have a greater say in what goes on. They can be given more flexible schedules and a chance to develop more skills on the job. Overtime can be made voluntary rather than mandatory.

Changes in the work environment could lead to a much healthier work force, Landsbergis said.

"We've known for a while that the risk of high blood pressure goes up with age," he said. "The question has been why. We think work stress is one of the reasons. In more primitive societies blood pressure doesn't go up at all with age. People reach the age of 70 and they still have blood pressure readings of 100/60."

SOURCE: American Journal of Epidemiology 2003;157:998-1006.