Impact of high job strain on health over time
A doctoral thesis on ‘Psychosocial job stress in relation to health’ at Ghent University reveals significant health effects of stressful jobs, including a greater probability of high blood pressure, lower back pain and depression. A further noteworthy finding was the observed gender difference in work-related health outcomes: women with stressful jobs were more exposed to psychological health problems while men were more likely to report physical health problems.
The doctoral thesis on Psychosocial job stress in relation to health (2007) by Els Clays from the University of Ghent, Belgium, aimed to examine the perception of psychosocial job stress in relation to health outcomes within the longitudinal Belstress (in Dutch) study. In terms of methodology, the research is based on the ‘Job demand-control-support (JDCS)’ model, introduced by Robert Karasek in the 1970s. According to this model, the most adverse job-related strain reactions are to be expected in jobs which are characterised by high psychological demands and low decision latitude (autonomy and freedom to use one’s skills) or job control, alongside low social support at the workplace.
Belstress study methodology
Belstress is a large epidemiological cohort study about stress at work and related health problems, such as cardiovascular and other diseases, and sickness absence. The first research phase covered the period 1994–1998 and included a total of 21,419 respondents aged between 35 and 59 years. The sample was selected in 25 companies or public administration organisations across Belgium. Data were gathered through self-administered questionnaires and bio-clinical examinations.
The second study phase took place from 2002 to 2004 and involved nine of the original 25 companies or public administration organisations. All of the workers who had participated in the first research phase and who were still working in the same companies were invited to participate again. A total of 2,821 workers, including 1,950 men and 871 women, partook in the second phase of the Belstress survey. Data were again collected through self-administered questionnaires and bio-clinical examinations.
In terms of psychosocial stress at work and related health outcomes, the doctoral thesis reveals the following findings.
- Workers’ perceptions over time: The first particular objective of the thesis was to examine long-term changes in the perception of job characteristics. As far as the nature and extent of intra-individual changes over time were concerned, the perception of psychological and physical job demands, job control and social support remained relatively stable, while a substantial increase in feelings of job insecurity was noted.
- Relation between job strain and high blood pressure: The second objective was to explore some possible explanatory mechanisms in the alleged relation between stress at work and coronary heart disease. Within a subsample of the second Belstress study, job strain was related to 24-hour ambulatory blood pressure (BP) measurements. A group of 89 middle-aged male and female workers perceiving high job strain and an equally large number of workers perceiving no high job strain wore an ambulatory BP monitor over 24 hours on a regular working day. Workers with high job strain experienced significantly higher blood pressure than those who did not perceive high job strain, and this not only at work, but also at home and during sleep.
- Impact of psychosocial job stress on other health outcomes: The third objective was to examine, in a longitudinal perspective, the role of psychosocial job stress in some health outcomes other than cardiovascular disease, namely musculoskeletal complaints and mental health. The impact of psychosocial – both work-related and non work-related – factors on the prevalence of lower back pain was assessed, on average over a six year interval, within a sample of 2,556 workers having a stable job. The study findings revealed that psychosocial factors constituted non-negligible risks for lower back pain. Moreover, within a population of 2,139 middle-aged workers free of high depression scores at baseline, job stress increased the risk for developing high levels of depression symptoms six years later. Frequent high job strain was associated with an increased risk of developing high levels of depression symptoms.
- Gender effect: The observed gender difference was significant in terms of health effects resulting from stressful jobs and careers. Women had a higher probability of being confronted with mental health problems, such as depression, while men were more likely to report physical health problems, such as back pain.
- Proven value of JDCS model: Overall, the JDCS model proved to be of value in the context of the stress and health studies presented in this thesis. Decision latitude had a much higher predictive value than did job demands, which is in line with other research findings.
As the study on psychosocial job stress in relation to health highlights, the existing body of knowledge on stress at work and related health outcomes is becoming increasingly impressive, but to effectively transform this knowledge into prevention strategies remains a major challenge. In this regard, the study recommends that intervention measures should focus on enhancing the decision latitude of workers in order to improve work-related health and well-being.
Guy Van Gyes, Higher Institute for Labour Studies (HIVA), Catholic University of Leuven