In order to bring you the best possible user experience, this site uses Javascript. If you are seeing this message, it is likely that the Javascript option in your browser is disabled. For optimal viewing of this site, please ensure that Javascript is enabled for your browser.
Did you know that your browser is out of date? To get the best experience using our website we recommend that you upgrade to a newer version. Learn more.

We use cookies to optimise the design of this website and make continuous improvement. By continuing your visit, you consent to the use of cookies. Learn more

Working overtime linked to increased CHD risk

Eur Heart J 2010; Advance online publication

Overtime work is associated with increased risk for incident coronary heart disease (CHD) independently of traditional risk factors, analysis of the Whitehall II prospective cohort shows.

People working 3–4 hours overtime per day had a 1.6-fold increased risk for incident CHD during the average 11-year follow-up compared with employees who worked no overtime.

"Our findings suggest a link between working long hours and increased CHD risk, but more research is needed before we can be confident that overtime work would cause CHD. In addition, we need more research on other health outcomes, such as depression and Type 2 diabetes," commented lead author Marianna Virtanen (Finnish Institute of Occupational Health, Helsinki).

The study was based on phase 3 of the Whitehall II study of UK civil servants and included 6014 participants (4262 men and 1752 women) who were aged 39–61 years, free from CHD, and working full time at baseline in 1991–1994.

When surveyed at this time, 3526 (54%) reported that they did not usually work overtime, while 1247 (21%) worked approximately 1 hour, 894 (15%) approximately 2 hours, and 617 (10%) around 3–4 hours extra on top of their normal working hours each day.

During follow-up lasting until 2002–2004, there were 369 incident CHD events (coronary death, nonfatal myocardial infarction, or definite angina), giving a rate of 5.46 events per 1000 person-years.

In multivariable analysis adjusting for sociodemographic factors, working 3–4 hours overtime (but not 1 or 2 hours) was associated with incident CHD, at a hazard ratio of 1.6 (p=0.005).

Further adjustment for all potential CHD risk factors changed the association little; in the fully adjusted model, including Type A behavior pattern, the hazard ratio was 1.56 (p=0.011).

Virtanen noted: "We did not measure whether subsequent changes in these factors during the follow-up period altered the association. One plausible explanation… could be that adverse lifestyle or risk factor changes are more common among those who work excessive hours compared with those working normal hours.
"Another possibility is that the chronic experience of stress (often associated with long working hours) adversely affects metabolic processes."

In a related editorial, Gordon McInnes (University of Glasgow, UK) commented that, despite the authors’ reservations above, the data "reinforce the notion that work stress attributable to overtime is associated, apparently independently, with an increased risk of CHD."

McInnes continued: "A trend for risk to be related to hours of overtime worked supports this conclusion. If the effect is truly causal, the importance is much greater than commonly recognized. Overtime-induced work stress might contribute to a substantial proportion of cardiovascular disease"

Read the abstract

MedWire ( is an independent clinical news service provided by Current Medicine Group, a part of Springer Science+Business Media. © Current Medicine Group Ltd; 2010