Excess Working Hours Increases Risk of Stroke

Professor Mika Kivimäki Chair of Social Epidemiology Epidemiology & Public Health Institute of Epidemiology & Health Faculty of Population Health Sciences University College London London MedicalResearch.com Interview with:
Professor Mika Kivimäki

Chair of Social Epidemiology
Epidemiology & Public Health
Institute of Epidemiology & Health
Faculty of Population Health Sciences
University College London

Medical Research: What is the background for this study? What are the main findings?

Prof Kivimäki:  Long working hours have been implicated in the cause of cardiovascular disease, but the evidence is limited. We conducted a systematic review of published studies on this topic and located additional individual-level data by searching open-access data archives and by including unpublished data from IPD-Work, a consortium of prospective cohort studies. This resulted in a pooled sample of over 600,000 men and women who were followed for cardiovascular disease 7-8 years after the assessment of working hours. During the follow-up, more than 4700 participants had a coronary event and 1700 had a stroke.

Our findings show that individuals who worked 55 hours or more per week had a 1.3-times higher risk of stroke compared to those working standard 35-40 hours. This finding remained unchanged in analyses adjusted for other stroke risk factors, such as age, sex, socioeconomic position and health behaviours.

Medical Research: What should clinicians and patients take away from your report?

Prof Kivimäki:  Clinician and patients should be aware that long working hours is associated with an increased risk of stroke. As our study was observational, we do not provide strong evidence for cause and effect.  This would be most robustly tested using randomised controlled trials or perhaps natural experiments.  Until such data are available, we suggest that prevention proceeds along established lines of multifactorial cardiovascular disease risk reduction:  keeping blood pressure, lipid levels and blood glucose within the normal range, adequate physical activity, eating and drinking healthfully, avoiding overweight, and avoiding excessive stress. Management of vascular risk factors is particularly important for individuals who work long hours.

Medical Research: What recommendations do you have for future research as a result of this study?

Prof Kivimäki:  Given that the standard risk factors measured in our study do not appear to explain the working hours-stroke link, mechanistically-orientated work is now needed to understand what underlies this relationship.


Long working hours and risk of coronary heart disease and stroke: a systematic review and meta-analysis of published and unpublished data for 603838 individuals

Kivimäki, Mika et al.
The Lancet Published Online: 19 August 2015

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Professor Mika Kivimäki (2015). Excess Working Hours Increases Risk of Stroke MedicalResearch.com

Last Updated on August 20, 2015 by Marie Benz MD FAAD