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Heart risks higher in overtime workers

People who work overtime more likely to suffer and die from heart disease

OnMedica Staff

Friday, 14 May 2010

People who work overtime are much more likely to suffer and die from heart disease, research has shown, but the reasons remain unclear.

Analysis of the long-term Whitehall II epidemiological study, published online in the European Heart Journal this week, shows that working at least 3 hours longer than a ‘normal’ 7-hour day is linked with a 60% increase in a person’s risk of non-fatal heart attack, angina and death from heart disease.

Risk factors such as smoking, being overweight or having high levels of cholesterol, measured at the start of the study in the 10,308 London civil servants who are participating, do not explain the association.

The authors say their results showed that working overtime was related to type A behaviour pattern, psychological distress manifested by depression and anxiety, and possibly with not enough sleep, or not enough time to unwind before going to sleep.

Other possible explanations for the association include high blood pressure that is associated with work-related stress but not apparent during medical examination; and the fact that those employees who work overtime being may also be more likely to work while ill, ignore symptoms of ill health and not seek medical help.

However, the findings were independent of all of the above factors, and so they could not necessarily provide the full explanation for why overtime was associated with the higher risk of heart disease. The authors said: “We did not measure whether subsequent changes in these factors during the follow-up period altered the association.

“One plausible explanation for the increased risk 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 working long hours) adversely affects metabolic processes.”

Commenting on the research, Gordon McInnes, from the University of Glasgow’s Western Infirmary, echoes the authors’ warnings about the limitations of the study, but writes: “Despite the above reservations, these data from a large occupational cohort reinforce the notion that work stress attributable to overtime is associated, apparently independently, with an increased risk of coronary heart disease.

“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.”

Until answers to the outstanding questions are found, Prof McInnes writes: “Physicians should be aware of the risks of overtime and take seriously symptoms such as chest pain, monitor and treat recognized cardiovascular risk factors, particularly blood pressure, and advise an appropriate lifestyle modification.”

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