Objectives Psychological stress may influence both susceptibility and severity of infections. Although work-related stress is a widespread concern among many employees, few studies have been conducted with the focus on work stressors and infections. We therefore aimed to investigate this association in a prospective cohort study.
Methods Our study included 25 029 employed individuals who filled-out a questionnaire in September 1997 and were followed through record linkages until retirement or December 2016. Work stress was assessed at baseline using a Swedish version of the Demand-Control Questionnaire, whereas hospital contacts related to infections were identified from the National Patient Register. We fitted extensions of the standard Cox model to account for recurrent infections.
Results In total, we observed 8257 infections. Individuals in the third tertile of job demand had a 13% higher hazard of infections (HR=1.13; 95% CI=1.03 to 1.24) compared with individuals in the first tertile, specifically an increased incidence of upper respiratory tract infections (HR=1.15; 95% CI=1.00 to 1.33) and urinary tract infections (HR=1.31; 95% CI=1.09 to 1.57) was found. Employees with the highest job control (third tertile) had no lower risk of infections than individuals in the lowest tertile (HR=1.02; 95% CI=0.92 to 1.13). When combining the demand and control dimensions into job strain scale, no association between high job strain and infections was observed (HR=1.08; 95% CI=0.97 to 1.21).
Conclusion High job demand, but not low job control, is associated with an increased occurrence of infections. No difference was observed in workers with high strain jobs compared with those with low strain jobs.
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Contributors FG analysed the data, wrote the first draft of the paper and edited the paper according to co-authors’ suggestions. RB contributed to the statistical analyses and critically revised the paper. H-OA made substantial contributions to data and funding acquisition and provided critical feedbacks to the paper. TA helped with the interpretation of the results and contributed to the writing of the paper. YTL supervised the project and contributed to the final version of the paper.
Funding This work was supported by ICA AB; Telefonaktiebolaget LM Ericsson; the Swedish Cancer Society (Grant CAN 2012/591) and a Karolinska Institutet Distinguished Professor Award (2368/10-221).
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The study was approved by the Regional Ethical Review Board at Karolinska Institutet and all participants provided informed consent.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data may be obtained from a third party and are not publicly available. Researchers can obtain access to data by contacting the Swedish National March Cohort steering committee (https://ki.se/en/meb/the-swedish-national-march-cohort-nmc). To gain access, data requestors will need to sign a data access agreement.
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