Thursday May 6 2010
The study looked at women's stress levels, not job seniority
“High flying career women with stressful jobs face a higher risk of heart disease,” the Daily Mail has claimed.
This news story is based on Danish research in 12,000 female nurses over 45 years of age, which compared their perceived work-related stress to their risk of heart disease over the next 15 years.
Despite the newspaper claims, this research looked at nurses' perceived levels of stress and not their status or seniority. Nurses who felt they were under a high level of work pressure were found to have a higher risk of heart disease than those who felt they were under an acceptable amount.
Where did the story come from?
Dr Haren Allesøe and colleagues from Glostrup University Hospital, Denmark carried out this research. The funding sources of this study were not stated.
The study was published in the peer-reviewed medical journal Occupational and Environmental Medicine.
This research was generally covered well by the newspapers. However, the research did not stratify women by their occupation, so newspaper suggestions that “high flying career women” are at increased risk are not supported by this study. The research actually looked at general measures of perceived stress and speed in the workplace, which may be independent of how senior a position a woman holds.
The Daily Express stated that “women who juggle a high-flying career and a family could pay a steep price for success”. Again, the research did not look at how having children affected the risk of heart disease.
What kind of research was this?
This was a cohort study that looked at whether pressure at work and associated stresses affected the likelihood of heart disease in women.
Cardiovascular disease affects as many women as men in industrialised countries. The researchers suggest that studies in men have shown that a combination of excessive psychological demands and a feeling of a low degree of control within the workplace have been associated with an increased risk of ischaemic heart disease (IHD) in men. However, there has been less research on how such work stress affects women. Therefore the researchers investigated work-related stress in a cohort of Danish nurses and their subsequent risk of developing ischaemic heart disease, e.g. angina and heart attacks.
What did the research involve?
The Danish Nurse Cohort Study was established in 1993. A total of 23,170 nurses who were over 45 years old and members of the Danish Nurses’ Association were given a questionnaire on health and lifestyle, which included questions on occupational status and working conditions at this time.
Women who had retired, were not working, or had been previously hospitalised for ischaemic heart disease (IHD) were excluded from the study. In total, 12,116 women who fulfilled the criteria returned the questionnaire. The average age of the women was 51 years old.
The researchers asked the women two questions on work pressure and aspects of work control or job influence:
- What is the work pressure/work speed at your work?: Much too low, a little too low, suitable, a little too high or much too high?
- Normally, how great is your influence on the organisation of your daily work?: A major influence, a certain influence or a minor/no influence?
The questionnaire also asked about age, marital status, number of children, the nature of the individual’s work, working hours, shift working, physical activity at work, family history of heart disease, diabetes, menopausal status, body mass index, smoking history, alcohol intake and amount of physical activity the individual did.
Using the National Patient registry of Hospital Discharges, the researchers were able to assess whether any of the women had experienced a heart attack, had angina or had any other signs of heart disease up until February 2008.
What were the basic results?
They found that 60% of the women reported that their work pressure ranged from ‘a little bit too high’ to ‘much too high’. In analyses that took into account the women’s age, the nurses who reported that their work pressure was a little too high had a 25% increased risk of IHD compared to those who felt that they had acceptable work pressure (Hazard Ratio [HR] 1.25, 95% confidence interval (CI) 1.04 to 1.50).
Nurses who reported work pressure to be much too high had a 47% increased risk of developing IHD compared to those reporting an acceptable work pressure (HR 1.47, 95 CI, 1.14 to 1.88). This elevated risk was still significant after they had taken into account other factors that could contribute to the risk of developing heart disease, such as a family history of heart disease, diabetes, menopausal status, body mass index, smoking, alcohol consumption and the amount of exercise they did (HR 1.35, 95%CI 1.03 to 1.76).
The researchers also took into account whether the nurses did shift work, and the degree of physical activity that their job entailed. After these adjustments, the risk of IHD was still higher in the group of nurses who felt under too much pressure than in those nurses who did not feel that their job had a significant degree of work pressure (HR 1.38, 95% CI 1.04 to 1.81).
In a separate analysis, the researchers looked at the risk of heart disease in a fixed five-year period. Compared to women who felt that their work pressure was of an acceptable level, the risk was 60% higher for nurses who felt that their work pressure was a little too high, and 97% higher for women who felt that their work pressure was much too high.
How did the researchers interpret the results?
The researchers concluded that in female nurses “self-reported work pressure that was too high was a predictor of heart disease”. They added that “this study adds to the previous body of evidence suggesting harmful effects of excessive psychological demands at work on cardiac health, but is one among very few that demonstrates the effect among women”.
They also suggest that their results should be taken into account in primary prevention, and additional work should be carried out to identify factors that contribute to people feeling under excessive work-related pressure.
This study followed a large cohort of Danish nurses and found an association between a perceived high work pressure and an increased risk of heart disease. The study was conducted well and made adjustments to account for other factors that could contribute to a risk for heart disease. There are some limitations, many of which the authors highlighted.
- A general problem in this type of research is the use of different measures of psychosocial work exposures. This study only measured one aspect of job demands and work pressure. Other aspects that may contribute to a stressful experience at work were not measured.
- Self-reported levels of work pressure are a subjective measurement, and different women doing the same job may report different degrees of work pressure. They are arguably a measure of how an individual responds to stress rather than a measure of how inherently stressful a job is.
- The study focused on women of one occupation – nursing. It is possible that people with different jobs may have different job demands and may experience those job demands differently.
- Additionally, the women were all above 45 years of age. Younger women may have different work histories and experiences, therefore this study may not be directly applicable to the UK female workforce.
- The population studied was a group of nurses. It is possible that their attitudes to health, and therefore risk of diseases, differ from those of the wider population.
- Another possible limitation is that the study included women who already had heart disease at baseline, as only those who had been admitted to hospital with IHD were excluded.
This research suggests that excessive psychological demands at work can affect cardiac health in women. Further research is needed to assess which specific factors in a workplace contribute towards a perceived high work pressure so that preventative measures to improve mental wellbeing in the workplace can be developed.