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Job strain linked to heightened risk of early death in men with heart disease/diabetes

Findings suggest that controlling cholesterol and high blood pressure alone unlikely to cut excess risk

Caroline White

Wednesday, 06 June 2018

Having a demanding job with little control over it is associated with an increased risk of early death in men with coronary heart disease, stroke, or diabetes, finds an international study* of more than 100,000 adults, published in The Lancet Diabetes & Endocrinology journal.

But no such associations were found for women with or without cardiovascular or metabolic disease.

“Work is a common source of stress in adulthood, triggering natural stress responses that were programmed in our bodies generations ago. These can result in physical reactions to situations like work stress, and our findings give evidence for there being a link between job strain and risk of premature death in men with cardiometabolic diseases, such as coronary heart disease, stroke, and diabetes,” comments lead author Professor Mika Kivimäki, of University College London.

“These findings suggest that controlling blood pressure and cholesterol levels alone are unlikely to eliminate the excess risk associated with job strain in men with cardiometabolic disease. Other interventions might be needed at least for some patients – possibly including stress management as part of cardiovascular disease rehabilitation, job redesign, or reducing working hours. However, more research will be needed to identify which specific interventions might improve health outcomes in men with coronary heart disease, stroke, or diabetes," he adds.

The study, which began in 1985, is the largest of its kind (102,633 men and women) and includes seven cohort studies from Finland, France, Sweden, and the UK. It included 3,441 adults with cardiometabolic disease (1,975 men and 1,466 women) who were asked about their lifestyle and health at the start of the study.

Their health was then tracked for an average of 13.9 years, during which time 3,841 participants died.

The study included two types of work stress: job strain (having high work demands and low control over them) and effort-reward imbalance (putting in lots of effort, but getting little reward in return).

After taking account of socioeconomic and several known conventional and lifestyle risk factors, the researchers found that, among men with cardiometabolic disease, those experiencing job strain had a 68% greater risk of premature death than men who had no job strain.

This heightened risk was even present in men with cardiometabolic disease who had achieved their treatment targets, including those with a healthy lifestyle (not being obese, being physically active, not smoking, and not drinking heavily), and normal blood pressure and cholesterol levels.

There was no association between risk of premature death and effort-reward imbalance in men with cardiometabolic disease, but men without cardiometabolic disease had a slightly heightened risk associated with this type of work stress.

Neither type of work stress was associated with an increased risk of early death for women with or without cardiometabolic disease.

Job stress may potentially affect the body in several ways, including hijacking natural responses to stress through heightened levels of the stress hormone cortisol, which increases glucose production and limits the effect of insulin, potentially leading to worse prognosis in diabetes.

Increased inflammation and activation of the ‘fight-or-flight’ response can also boost blood pressure and affect blood clotting, potentially increasing the risk of cardiac events in those who already have hardened arteries.

The authors point out that they only measured cardiometabolic disease and work stress at the start of the study, so could not account for severity of disease or how it might have changed over time. Nor did they control for blood pressure or cholesterol levels in all cohorts due to missing data, and this might have overestimated the potential impact of job strain.

Writing in a linked comment**, Yulong Lian, Nantong University, China, points to other important factors associated with cardiometabolic disease which might have influenced these findings: “The prevalence of poor mental health, such as psychological distress, clinical depression, and anxiety, is higher among patients with cardiometabolic disease than in the general population. Furthermore, compared with people with no stress, those with work stress tend to have a higher prevalence of poor mental health [...]

“Further research into the mechanisms responsible for these differences in the effects of work stress would not only improve understanding of the prognosis of cardiometabolic disease, but also inform health policy makers and guideline committees about the need for sex-specific workplace interventions for the treatment and management of cardiometabolic disease.”

*Kivimäki M, Pentti J, Ferrie E. J, et al. Work stress and risk of death in men and women with and without cardiometabolic disease: a multicohort study. The Lancet Diabetes & Endocrinology, 5 June 2018, DOI:10.1016/S2213-8587(18)30140-2
**Lian, Y. Stress at work in patients with cardiometabolic disease. The Lancet Diabetes & Endocrinology, 5 June 2018, DOI: 10.1016/S2213-8587(18)30172-4

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