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Canadian Journal of Cardiology

Investigating Cortisol Production and Pattern as Mediators in the Relationship Between Shift Work and Cardiometabolic Risk

Published:February 09, 2018DOI:https://doi.org/10.1016/j.cjca.2018.02.006

      Abstract

      Background

      Shift work is a risk factor for many diseases, including cardiovascular disease. Although the biological pathways are still unclear, it is hypothesized that cortisol disruption during night work is an intermediate. The objective of this study is to determine whether total cortisol production and cortisol pattern mediate the relationship between current shift work and cardiometabolic risk (CMR) among female hospital employees.

      Methods

      A cross-sectional study was conducted among 326 female employees (166 rotating shift workers, 160 day workers), recruited from a hospital in Southeastern Ontario, Canada, during 2011 to 2014. Participants completed a baseline interview, questionnaire, and clinical exam. Urine samples were collected over two 24-hour periods and used to analyze creatinine-adjusted cortisol, which was then used to calculate total cortisol production (AUCG), and pattern (AUCI). Mediation analysis was performed to test the mediating effect of cortisol in the relationship between shift work and a continuous CMR score.

      Results

      Current shift work is associated with a 0.52 higher CMR score (95% CI: 0.15, 0.89), a lower cortisol output (AUCG), and a flatter pattern (AUCI) over a 2-day period. AUCG is a partial mediator in the relationship between shift work and CMR, whereas AUCI is not. AUCG is also associated with CMR while controlling for shift work, suggesting that lower total cortisol production is also linked to CMR in non-shift workers.

      Conclusions

      Total cortisol production is a partial mediator in the relationship between rotating shift work and CMR among female hospital employees, whereas cortisol pattern is not a mediator.

      Résumé

      Contexte

      Le travail par roulement est un facteur de risque de nombreuses maladies, y compris les maladies cardiovasculaires. Bien que les mécanismes biologiques en cause ne soient pas encore élucidés, une hypothèse voudrait que la perturbation du métabolisme du cortisol pendant le travail de nuit soit un mécanisme intermédiaire. L’objectif de cette étude est de déterminer si la production de cortisol total et le profil du cortisol assurent la médiation du lien entre le travail par roulement en cours et le risque cardiométabolique (RCM) chez des femmes travaillant dans un hôpital.

      Méthodologie

      Une étude transversale a été menée auprès de 326 employées (166 employées ayant un travail en rotation et 160 employées de jour) recrutées dans un hôpital du sud-est de l’Ontario (Canada) entre 2011 et 2014. Les participantes ont passé une entrevue initiale, elles ont répondu à un questionnaire et passé un examen clinique. Des échantillons d’urine ont été recueillis pendant deux périodes de 24 heures aux fins d’analyse des taux de cortisol corrigés selon la créatinine; ces taux ont ensuite servi à calculer la production de cortisol total (ASCG) et le profil du cortisol (ASCI). Une analyse a été réalisée pour tester l’effet médiateur du cortisol dans le contexte du lien existant entre le travail par roulement et un score de RCM continu.

      Résultats

      Le travail par roulement en cours est associé à un score de RCM plus élevé de 0,52 (intervalle de confiance [IC] à 95 %: 0,15 à 0,89), à une élimination inférieure du cortisol (ASCG) et à un profil plus plat (ASCI) du cortisol sur une période de deux jours. L’ASCG est un médiateur partiel du lien entre le travail par roulement et le RCM, ce qui n’est pas le cas de l’ASCI. L’ASCG est également associée au RCM lorsqu’une correction est apportée en fonction du travail par roulement, ce qui indique que la production inférieure de cortisol total est également liée au RCM chez les personnes n’ayant pas un travail par roulement.

      Conclusion

      Contrairement au cycle du cortisol, la production de cortisol total est un médiateur partiel du lien existant entre le travail en rotation et le RCM chez les employées de l’hôpital de l’étude.
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