Low job control linked to hypertension in men

February 27, 2013 (Toronto, Ontario)—Low job control is associated with an increased risk of hypertension among men, but not women. This is according to a study by researchers at the Institute for Work & Health (IWH) and the Institute for Clinical Evaluative Sciences (ICES), published today in the Canadian Journal of Public Health.

Job control refers to the ability to make decisions about the way work is done or skills are used to meet the demands of the job. The study found that, among men reporting low job control, 27 per cent were diagnosed with hypertension during a nine-year period. This compared to 18 per cent among men reporting high job control.

Furthermore, the study found the proportion of cases of hypertension among men that could be attributed to low job control was 12 per cent, which is higher than the proportion of cases that could be attributed to poor health behaviours such as smoking, drinking, not getting enough exercise, and not eating enough fruits and vegetables. Indeed, low job control was second only to obesity, to which 26 per cent of cases of hypertension among men could be attributed.

Primary prevention programs to reduce hypertension are largely aimed at changing unhealthy behaviours, says IWH Scientist Dr. Peter Smith, who led the research. But this study suggests that prevention strategies might also assess the potential for modifying work environments as a hypertension control intervention.

What those workplace prevention strategies should be remains unclear. As IWH President and Senior Scientist Cam Mustard points out, we don’t have solid evidence on how best to increase job control. Furthermore, adds Mustard, a member of the study team, we don’t yet have research to show interventions to increase job control would, indeed, lower the incidence of hypertension among men.

Hypertension, or high blood pressure, is a risk factor for strokes and heart attacks, among other health ailments. Its prevention and management is a public health concern in Canada and other developed countries. In Ontario, the incidence of hypertension increased by 60 per cent over the 10-year period 1995 to 2005: from 153 to 244 cases per 1,000 Ontarians.

The study, which was funded by the Canadian Institutes of Health Research, followed 6,611 actively employed (but not self-employed) 35- to 60-year olds in Ontario who had not been previously diagnosed with hypertension. These people were drawn from the 2000-2001 Canadian Community Health Survey (CCHS), which provided information on their health behaviours, their psychosocial work environment (including job control), and other work and personal factors.

This information was then linked to the Ontario Health Insurance Plan (OHIP) database for physician services and the Canadian Institute for Health Information Discharge Abstract Database (CIHI-DAD) for hospital admissions up to March 2010. This allowed researchers to detect new diagnoses of hypertension among the group for a nine-year period.

The researchers found that, in all, 19 per cent of the study group developed hypertension during this time, with a higher incidence among men (21 per cent) than women (18 per cent). After taking a range of personal and work factors into account that could affect the incidence of hypertension, men with the lowest levels of job control still had a significantly increased risk of developing hypertension than men with the highest levels of job control (i.e. 27 per cent versus 18 per cent, which represents an 85 per cent increase in risk among men with low job control). This difference was not found in women. As well, no relationship between high job strain (i.e. high psychological demands and low job control) and hypertension was found among either men or women.

The full study is available in the January/February 2013 issue of the Canadian Journal of Public Health (vol. 104, no. 1). Its full citation is: Smith PM, Mustard CA, Lu H, Glazier RH. Comparing the risk associated with psychosocial work conditions and health behaviours on incident hypertension over a nine-year period in Ontario, Canada, Can J Public Health 2013;104(1):e82-e86.

A previous study from the same group of IWH and ICES researchers, using the same nine-year study data, found low job control is associated with an increased risk of diabetes among women, but not men. That study was published in the September issue of Occupational Medicine (vol. 62, no. 6, pp. 413-419): http://occmed.oxfordjournals.org/content/62/6/413.full (for the related media release, see: www.iwh.on.ca/media/2012-aug-21).

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of health-care issues. Its unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health-care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners and practitioners to make decisions about care delivery and to develop policy: www.ices.on.ca