Job Strain as a Risk Factor for Coronary Heart Disease: A Collaborative Meta-Analysis of Individual Participant Data

Study Questions:

What is the relation between job strain and coronary heart disease (CHD) based on a meta-analysis of published and unpublished studies?

Methods:

The investigators used individual records from 13 European cohort studies (1985–2006) of men and women without CHD who were employed at the time of baseline assessment. They measured job strain with questions from validated job-content and demand-control questionnaires. The authors extracted data in two stages such that acquisition and harmonization of job strain measure and covariables occurred before linkage to records for CHD. Incident CHD was defined as the first nonfatal myocardial infarction or coronary death.

Results:

A total of 30,214 (15%) of 197,473 participants reported job strain. In 1.49 million person-years at risk (mean follow-up 7.5 years [standard deviation 1.7]), the investigators recorded 2,358 events of incident CHD. After adjustment for sex and age, the hazard ratio for job strain versus no job strain was 1.23 (95% confidence interval [CI], 1.10-1.37). This effect estimate was higher in published (1.43, 1.15-1.77) than unpublished (1.16, 1.02-1.32) studies. Hazard ratios were likewise raised in analyses addressing reverse causality by exclusion of events of CHD that occurred in the first 3 years (1.31, 1.15-1.48) and 5 years (1.30, 1.13-1.50) of follow-up. The authors noted an association between job strain and CHD for sex, age groups, socioeconomic strata, and region, and after adjustments for socioeconomic status, and lifestyle and conventional risk factors. The population-attributable risk (PAR) for job strain was 3.4%.

Conclusions:

The authors concluded that these findings suggest that prevention of workplace stress might decrease CHD incidence.

Perspective:

This study suggests that job strain is associated with a small, but consistent increased risk of an incident event of CHD. Furthermore, adjustment for lifestyle and conventional risk factors, and for age, sex, and socioeconomic status, did not substantially change the magnitude of this association. The PAR for job strain was 3.4%, and while notable, the PAR is substantially less than that for standard risk factors, such as smoking (36%), abdominal obesity (20%), and physical inactivity (12%). While society strives to reduce job strain and improve working conditions, we also need to continue to focus on eliminating smoking and encouraging lifestyle modifications (i.e., healthy diet and regular physical activity), which are far more impactful methods of reducing the incidence of cardiovascular diseases.

Keywords: Myocardial Infarction, Life Style, Employment, Coronary Disease, Risk Factors, Questionnaires


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