Shift work in young adults and carotid artery intima–media thickness: The Cardiovascular Risk in Young Finns study

Puttonen, Sampsa; Kivimäki, Mika; Elovainio, Marko; Pulkki-Råback, Laura; Hintsanen, Mirka; Vahtera, Jussi; Telama, Risto; Juonala, Markus; Viikari, Jorma S.A.; Raitakari, Olli T.; Keltikangas-Järvinen, Liisa

doi:10.1016/j.atherosclerosis.2009.01.016

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Volume 205, Issue 2 , Pages 608-613, August 2009

Shift work in young adults and carotid artery intima–media thickness: The Cardiovascular Risk in Young Finns study

Sampsa Puttonen
- Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A, FIN-00250 Helsinki, Finland
- Corresponding author at: Finnish Institute of Occupational Health, Center of Expertice for Human Factors at Work, Topeliuksenkatu 41 a A, FIN-00250 Helsinki, Finland. Tel.: +358 30 474 2526.
Mika Kivimäki
- Department of Epidemiology and Public Health, University College London 1-19, Torrington Place London WC1E 6BT, UK
Marko Elovainio
- National Research and Development Centre for Welfare and Health, PO Box 220, FIN-00531 Helsinki, Finland
Laura Pulkki-Råback
- Department of Psychology, University of Helsinki, FIN-00014 Helsinki, Finland
Mirka Hintsanen
- Department of Psychology, University of Helsinki, FIN-00014 Helsinki, Finland
Jussi Vahtera
- Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A, FIN-00250 Helsinki, Finland
Risto Telama
- LIKES Research Center, Keltavuokko 4 C, 40520 Jyväskylä, Finland
Markus Juonala
- Department of Medicine, Kiinamyllynkatu 4-8, FIN-20520 University of Turku, Finland
Jorma S.A. Viikari
- Department of Medicine, Kiinamyllynkatu 4-8, FIN-20520 University of Turku, Finland
Olli T. Raitakari
- Department of Clinical Physiology, Kiinamyllynkatu 4-8, FIN-20521 University of Turku, Finland
Liisa Keltikangas-Järvinen
- Department of Medicine, Kiinamyllynkatu 4-8, FIN-20520 University of Turku, Finland

Received 1 August 2008; received in revised form 22 December 2008; accepted 10 January 2009. published online 13 February 2009.

Abstract

Objective

Shift work is associated with an elevated risk of cardiovascular disease, but the timing or mechanisms of this association is unclear.

Methods and results

We examined the relationship between shift work and subclinical atherosclerosis in 1543 (712 men and 831 women, 24–39 years old) young adults as part of the ongoing population-based Cardiovascular Risk in Young Finns study. Carotid atherosclerosis was assessed by measuring the thickness of the common carotid artery intima–media (IMT) complex with ultrasound and carotid plaque. Working schedules were categorized as day work or shift work (2- or 3-shift work, regular evening or night work). In men, shift work was associated with higher mean IMT (B=0.029, p=0.021), maximum IMT (B=0.029, p=0.028), and a 2.2-fold odds of carotid plaque (95% CI, 1.2–4.0). These relationships persisted after adjustment for age and risk factors, such as low socio-economic position, job strain, smoking, diet, family history of CHD, physical inactivity, alcohol consumption, obesity, homocysteine, C-reactive protein, blood pressure, and lipids. In women, no association was found between shift work and carotid atherosclerosis indicators.

Conclusions

Our results suggest that shift work accelerates the atherosclerotic process and that the effects of shift work on subclinical atherosclerosis are observable in men already before age 40.

Keywords: Atherosclerosis, Carotid arteries, Epidemiology, Risk factors, Shift work