People who report high levels of job-related stress are at an increased risk of being hospitalized for peripheral artery disease according to a study published this week in the Journal of the American Heart Association.
“Our findings suggest that work-related stress may be a risk factor for peripheral artery disease in a similar way as it is for heart disease and stroke,” says Katriina Heikkila, the study’s lead author and a senior researcher at Sweden’s Karolinska Institute, in a released statement.
Peripheral artery disease (PAD) occurs when the blood vessels that carry blood from the heart — usually in the legs — become too narrow or blocked due to a buildup of fatty deposits (atherosclerosis). The classic symptom of PAD is pain or cramping in the hips, thighs or calf muscles that worsens with physical activity (such as walking) and then gets better after rest. Four in 10 people with the condition experience no leg pain, however. Other symptoms include leg numbness or weakness, a change in the color of the legs, coldness in the lower leg or foot, and sores on the leg or foot that don’t heal.
More than 200 million people worldwide have PAD, including 8.5 million people in the United States. Increasing age (being 50 or older) is a major risk factor for the condition, as is type 2 diabetes, high blood pressure and/or high cholesterol.
If untreated, PAD can lead to heart attack, sudden cardiac arrest or stroke. It can also result in amputation of the foot or leg.
Although plenty of previous research has found a link between stress and several cardiovascular “outcomes” (such as the development of heart disease or stroke), few studies have looked specifically at the relationship between stress and PAD. The current study is meant to help fill that research gap.
For the study, Heikkila and her colleagues analyzed data from 11 separate studies conducted in Sweden, Finland, Denmark and the United Kingdom across two decades (1985-2008). The studies involved 139,000 participants, two-thirds of whom were women. Their average age ranged from 38 to 49 (depending on the study), and none had a history of PAD when the studies began.
In addition to gathering health and demographic information from the participants, the studies also had them fill out questionnaires designed to measure their level of work-related stress, or job strain. They were asked to rank statements that describe psychosocial aspects of their job. Some questions (such as “my job requires working very fast”) measured the demands of the job, while others (“my job allows me to learn new things”) measured how much self-control they felt the job gave them.
A combination of high-demand and low-control scores was defined as job strain. Just under a quarter of the participants — about 32,000 — reported job strain when they entered the studies.
Normal artery and artery with plaque buildup
The participants were followed for an average of almost 13 years. During that time, 667 of them were hospitalized for PAD.
The pooled data from the 11 studies revealed that people with work-related stress were 1.4 times more likely than those without it to have been hospitalized for PAD. That finding of increased risk was consistent among men and women, smokers and non-smokers and people of all socioeconomic status, although men, smokers and those with higher socioeconomic positions tended to be at greater risk.
No difference in the magnitude of the association between work-related stress and PAD was found among people with and without type 2 diabetes.
Limitations and implications
The study comes with plenty of caveats. Most notably, it is an observational study, so it can show only a correlation, not a causal relationship, between job strain and an increased risk of PAD.
In addition, as Heikkila and her co-authors note, there’s a possibility that some of the participants may have had early-stage, undiagnosed PAD when they entered the studies that were analyzed — a factor that could have influenced their results.
Still, “our findings support those of previous studies, pointing to a role of life stress in atherosclerotic disease,” the researchers point out.
Those findings have a biologically plausible explanation. “While there is limited evidence directly linking stress to atherosclerosis per se,” write the researchers, “[the] stress response is associated with increased systemic inflammation and elevated blood glucose, which may contribute to exacerbations and complications of PAD,” they explain.
Adding to this effect, they say, is the possibility that people who are under a lot of job strain may put off going to a doctor with early symptoms of PAD, thus delaying getting help for the condition until they need hospitalization.
FMI: You can read the study in full on the website for the Journal of the American Heart Association.