People working in high demand, low control jobs appear to be at increased risk ofstroke, a meta-analysis of six prospective cohort studies has revealed.The association between exposure to high job strain and an increased risk of stroke was particularly pronounced in ischemic stroke and in women but not in hemorrhagic stroke or in men, according to Dingli Xu, MD, of Southern Medical University, Guangzhou, China, and colleagues.”Individuals exposed to high job strain had a 22 percent higher risk of all stroke and 58 percent higher risk of ischemic stroke,” the investigators reported online inNeurology (Oct. 14, 2015). On the other hand, the risk of stroke was not increased in those with any other category of job stress, as determined using the demand-control model (DCM).
The four job stress categories used by the investigators included:
- Low Strain (low demand, high control) such as jobs held by architects and natural scientists;
- Passive (low demand, low control) such as janitorial, mining, and other manual labor jobs;
- Active (high demand, high control) such as jobs held by physicians, teachers, and engineers; and
- High Strain (high demand, low control) such as jobs held by waiters, waitresses, and nurses’ aids.
“These findings demonstrate that the combination of low control and high demand job characteristics is important for identifying those at higher risk of stroke,” they said. “High-risk subpopulations with high strain occupations combined with other cardiovascular risk factors should also be considered in controlled trials of interventions to prevent stroke,” remarked the investigators.
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In the analysis, Xu and colleagues searched PubMed, Embase, and PsycINFO and included six studies from the U.S., Asia, Sweden, and Finland 0n job strain and risk of stroke with a total of 138,782 participants.
The analysis showed:
- High strain jobs were associated with increased risk of stroke compared with low strain jobs;
- Increased risk was more pronounced for ischemic stroke;
- Risk of stroke was significant in women and nonsignificant in men;
- The difference in RRs in sex subgroups was not significant; and
- Neither active nor passive job characteristics were associated with an increased risk of stroke compared with low strain jobs.
In an earlier meta-analysis of data on 102,128 participants, reported in 2013 byMika Kivimaki, PhD, et al, the risk of coronary heart disease (CHD) was shown to be highest among participants who reported high job strain and unhealthy lifestyle behaviors, noted Xu and colleagues. These behaviors, including smoking, reduced physical activity, lower help-seeking behavior, and poor eating habits are also risk factors for stroke, they pointed out.That study also showed that even when people working in a high strain job had a healthy lifestyle, their risk of CHD was still 25 percent higher when compared with people who had no job strain.
“These results indicate that unhealthy lifestyles do not fully explain the CVD risks in people exposed to high job strain,” said the investigators. “Second, work stress is often associated with certain cardiovascular risk factors, such as metabolic syndrome, high body mass index, impaired glucose metabolism, and dyslipidemia, which are also known to be risk factors for stroke.”
Long-term work stress could lead directly to enhanced activation of the hypothalamic pituitary adrenal axis and sympathetic nervous system, noted Xu and colleagues. This in turn could lead to an elevated inflammatory response, destabilization of atherosclerotic plaques, accelerated cellular aging, enhanced cortisol secretion, and hemodynamic perturbations, as well as other risk factors for stroke, they said.
In an accompanying editorial, Jennifer J. Majersik of the Stroke Center at the University of Utah in Salt Lake City, UT, pointed out that none of the six studies included in the meta-analysis adjusted for vascular risk factors or captured measures of inflammation and metabolism. As a result, there may be unmeasured factors mediating stroke risk, she said.
“Once there is further clarity on this issue, high job strain may be considered an independent stroke risk factor — and one that is potentially modifiable,” she wrote.
In the meantime, Majersik said she answers patients’ questions about whether stress caused their stroke with a definite “Maybe.”