Article Text
Abstract
Background Though there is increasing evidence on the effect of long working hours (LWH) and stroke, few studies have distinguished stroke subtypes. We examined the associations between LWH and ischaemic or haemorrhagic stroke after adjusting for cardiovascular risk factors.
Methods From a national population-based cohort CONSTANCES, baseline questionnaires and initial health examinations were used to retrieve sociodemographic and cardiovascular risk factors from 2012 to 2018. LWH were defined as self-reported working time≥10 hours daily for at least 50 days per year. Incident cases of stroke were collected using International Classification of Disease codes recorded in the National Health Data System. Associations between LWH and stroke were investigated using multinomial models adjusted for cardiovascular risk factors.
Results Among the 160 751 participants who were free from stroke at baseline, exposure to LWH≥10 years was reported by 20 723 participants, and 190 incident cases of stroke were identified, including 134 ischaemic and 56 haemorrhagic. Exposure to LWH was associated with an elevated odds of ischaemic stroke (OR=1.61 (1.04–2.49)) and haemorrhagic stroke (OR=2.50 (1.38–4.53)) in unadjusted models. In adjusted multivariable models, only the LWH association with haemorrhagic stroke remained significant (aOR=1.92 (1.01–3.09)).
Conclusions LWH were associated with stroke, though it remained significant for haemorrhagic stroke only after adjustments. Differences in direct and indirect biological pathways and lack of power in the ischaemic subgroup may explain these results and further studies on the impact of mediating and effect measure modifying factors are needed. Nevertheless, policies that attenuate effects of both LWH and cardiovascular risks factor are warranted.
- Epidemiology
- Public health
- Longitudinal studies
- Occupational Stress
Data availability statement
Data may be obtained from a third party and are not publicly available. The data of the CONSTANCES cohort are protected by our national regulatory agency (‘Commission nationale de l’informatique et des libertés’, n°910486). However, the CONSTANCES cohort is ‘an open epidemiological laboratory’ and access to study protocols and data is available on reasonable request.
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Data availability statement
Data may be obtained from a third party and are not publicly available. The data of the CONSTANCES cohort are protected by our national regulatory agency (‘Commission nationale de l’informatique et des libertés’, n°910486). However, the CONSTANCES cohort is ‘an open epidemiological laboratory’ and access to study protocols and data is available on reasonable request.
Footnotes
Contributors MF is the guarantor of the study. MF and AD conceived and designed the study. MF and AD performed data analysis and drafted the manuscript. MF, GS, JL, AL, FP, AS, YR and AD analysed the results and critically reviewed the manuscript. All authors read and approved the final manuscript.
Funding No funding for the study (Authors are paid by their institutions). The CONSTANCES Cohort Study was supported and funded by the Caisse nationale d’assurance maladie (CNAM); it is an ‘Infrastructure Nationale en Biologie et Santé’ and benefits from ANR (ANR-11-INBS-0002) grant funding. CONSTANCES is also partly funded by Merck Sharp & Dohme (MSD), AstraZeneca, Lundbeck and L’Oréal through Inserm-Transfert. None of these funding sources had any role in the design of the study, collection and analysis of data or decision to publish.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.