As populations across the developed world grow older, Governments are keen to find ways to enable workers to stay active and fit for longer. We know work-related stress can lead to long-term health problems: but which types of employment histories are particularly harmful, and how do the effects play out over time? A new study by Morten Wahrendorf, Tarani Chandola and colleagues points to a need for early intervention with disadvantaged groups of workers.

Most studies on occupational stress focus on a particular point in time. But what if the effects of troubled working lives build up over many years, in terms of adverse employment trajectories over an extended time period? Some workers suffer repeated periods of unemployment throughout their working lives, for instance. We wanted to know how different types of work histories might be linked to health problems in later life.

We were able to examine these questions using data from the French CONSTANCES cohort study, which allowed us to combine information on participants’ employment histories from age 25-45 with health-related information.

Can stressful working lives lead to health issues over a long period? To address this question, we looked at a sub-sample of just over 90,000 people of the CONSTANCES study who had been in work between the ages of 25 and 45, and who had not had to leave work or take a break due to ill health during that period.

The information we had included the numbers of temporary jobs participants held and the number of job changes they had; how many times they were unemployed and how long they spent out of work. We could also see what sort of job they had and whether or not they gained promotion – this enabled us to identify if they suffered from job instability or other types of cumulative disadvantage.

Wear and tear

Participants in the study were also asked to fill in health questionnaires as well as undertaking medical examinations and giving blood samples. This enabled us to calculate their ‘allostatic load’ (AL) – a biological measure of the wear and tear on the body (i.e. the damage to the body) which accumulates as an individual is exposed to chronic stress throughout working life. And that is associated with long-term conditions such as heart disease, type-2 diabetes and depression.

In this study we were able to include measures on a total of 10 items to measure allostatic load, including blood pressure, lung function, waist-to-hip ratio, cholesterol levels, kidney function, fasting blood sugar and the immune and inflammatory system.

Men and women were considered separately and we were able to look at whether participants were in a stable relationship as well as their level of education.

Our key findings were as follows:

– Both men and women who suffered disadvantage at work had a higher allostatic load: it was possible to measure physical health effects linked to work stress. Women who had skilled or semi-skilled jobs had a higher load than managers or professionals. Both men and women suffered if they had been out of the labour market for six years or more.

–  Men who were rejected for promotion had slightly higher scores, as did women who had a high number of temporary jobs.

• Frequent job moves were not associated with ill-effects on health: these might be made for positive reasons such as promotion.
• The effects remained even after we controlled for other career characteristics. They were the same for all the different health indicators we looked at, bar one: kidney function.
• The impact on health was particularly high for those who had continuously been in low-skilled, high-stress types of work, with repeated or lengthy periods of unemployment.

Adversity

Our study suggests that people who suffer adversity in their working lives over an extended period are more likely to suffer long-term health conditions in later life. It underlines the importance of those links between chronic work stress and disease. 

The potential benefits of promoting healthy work conditions, particularly among more disadvantaged groups and at early stages of their working lives, are clear from this study. The potential benefits will support both employees, in helping them to stay healthy for longer, and employers, who could cut rates of sickness and retirement through ill-health.

Adverse employment histories and allostatic load: associations over the working life is by Morten Wahrendorf , Tarani Chandola , Marcel Goldberg, Marie Zins, Hanno Hoven and Johannes Siegrist, and is published in the Journal of Epidemiology and Community Health.