Impact of occupational stress on stroke across occupational classes and genders

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Abstract

The aims of the present study were to analyze the association between incident stroke, occupational class and stress and to examine whether the association is found in both men and women in a prospective study of Japanese male and female workers. A total of 3190 male and 3363 female Japanese community-dwelling workers aged 65 or under with no history of cardiovascular disease were followed. Occupational stress was evaluated using a demand-control questionnaire. The impact on stroke was examined in stratified analyses of occupational classes. We identified 147 incident strokes (91 in men and 56 in women) during the 11-year follow-up period. Men with high strain jobs (combination of high job demand and low job control) were nearly three times more likely to suffer from a stroke than men with low strain jobs (combination of low job demand and high job control). Among male workers in low occupational classes (blue-collar and non-managerial work), job strain was associated with a higher risk of stroke. In contrast, there was no association between job strain and incident stroke among male workers in high occupational classes (white-collar and managerial work). No statistically significant differences were found for stroke incidence among the job characteristic categories in all the female participants. However, significant, over five-fold excess risks were found among white-collar and managerial female workers exposed to high job strain, compared with their counterparts with low strain jobs. Our study of Japanese workers provided supportive evidence for vulnerability to occupational stress among lower occupational class workers in males but not in females.

Introduction

Previous studies have indicated that workers in lower occupational classes are more vulnerable to occupational stress than workers in higher occupational classes (Hallqvist et al., 1998, Kivimäki et al., 2002, Lynch et al., 1997, Theorell et al., 1998, Wege et al., 2008). Only a few studies have prospectively investigated the association between occupational class and occupational stress using stroke as the outcome (Kivimäki et al., 2009, Kuper et al., 2007, Toivanen, 2008, Toivanen and Hemström, 2008, Virtanen and Notkola, 2002). Of those, one study showed that female lower occupational class non-manual workers with low job control had a significantly higher risk of stroke mortality (Toivanen & Hemström, 2008). Other prospective studies did not test whether lower occupational class workers were more susceptible when exposed to occupational stress (Kivimäki et al., 2009, Kuper et al., 2007). Thus, there is no prospective study that has addressed different vulnerabilities to stress across occupational classes using incident stroke as an outcome. In addition, there may be gender differences in the health impact of socioeconomic factors as well as occupational stress (Kopp, Skrabski, Szekely, Stauder, & Williams, 2007). Nevertheless, few studies have addressed the potential interaction between gender and occupational or employment status and gender differences in work hazard exposures and the health impact. Furthermore, the prospective associations between occupational class/occupational stress and health outcomes have not been examined extensively outside Western societies. Data from the Jichi Medical School Cohort Study of a Japanese working population, a large-scale prospective cohort study, allowed an approach to this important issue. The aims of the present study were to analyze the association between incident stroke, occupational class and stress and examine whether the association is found in both men and women in a prospective study of Japanese male and female workers.

Section snippets

Study populations

Data were acquired from routine mass screening examinations for cardiovascular diseases in the aged, which were carried out in Japan in accordance with relevant legal regulations. The regulations required municipal governments to manage the program efficiently and to make it available to all residents who wished to participate. The local government office invited all potential participants in each community to attend screenings by sending letters or using public information channels. The

Results

Table 1 shows the relationships between occupational classes and the examined variables at baseline. Male white-collar workers were younger, had higher educational attainment and were less physically active than male blue-collar workers. The two occupational categories were significantly associated. Specifically, three-quarters of white-collar workers and a third of blue-collar workers filled supervisory or managerial positions. Regarding psychosocial job characteristics, active and, to a

Discussion

In a cohort of Japanese workers, we found a significantly higher risk of incident stroke in men with high job strain among blue-collar workers and those in non-managerial jobs, but not among white-collar workers or those in managerial positions. The opposite trends were observed in women, i.e., significant elevated risks among white-collar and managerial workers, but not among blue-collar workers or those in non-managerial positions. To the best of our knowledge, this is the first study to

Conclusion

The findings of this study suggest that the health impact of occupational stress characterized by high job demands and low control is greater among male workers in lower occupational classes. Amid significant changes in the working environment, it is imperative to accumulate observational data over a period of time to confirm the relationships between occupational class, occupational stress and stroke in Japanese women.

Conflict of interest

None.

Acknowledgment

This study was partly supported by a grant-in-aid from the Foundation for the Development of the Community, Tochigi, Japan, and by Grant-in-Aid for Scientific Research.

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