The new study, recently published in The Lancet, is the largest ever conducted to assess the connection between cardiovascular health and working hours.
The Centers for Disease Control and Prevention (CDC) estimates that coronary heart disease and stroke are ranked first and fifth, respectively, in the top 10 American causes of death.
Longer working hours have been evaluated before: Medical News Today reported last year that those working between 61 and 70 hours per week had a 42 percent increased risk of furthering coronary heart disease in comparison to those that work 40 hours and less (read here).
A survey conducted last year found that the average weekly working hours in the United States were higher than the traditional 40 hours quoted by the government. In the survey, full-time employees reported 47 average weekly work hours, which is almost an extra day of work.
Scientists from the University College London (UCL) carried out a systematic review and meta-analysis of several studies from the United States, Europe and Australia on the subject.
Data from 25 studies was evaluated which surveyed over 600,000 men and women from 3 geographic areas over the course of 8.5 years on average. Individuals working 55 hours and more had 13 percent higher risk of having coronary heart disease. Furthermore, the chances of having a stroke among overworked individuals was 33 percent higher and the risk rose accordingly to the amount of working hours: individuals working 41 to 48 hours per week had 10 percent increased chances of stroke and those working 49 to 54 hours per week had 27 percent.
Even when researchers took into account other factors such as age, economic status, sex, physical activity, smoking and alcohol consumption, high blood pressure and high cholesterol, the increased risk remained.
“The pooling of all available studies on this topic allowed us to investigate the association between working hours and cardiovascular disease risk with greater precision than has previously been possible. Health professionals should be aware that working long hours is associated with a significantly increased risk of stroke, and perhaps also coronary heart disease,” noted Mika Kivimäki, from UCL.
Urban Janlert, from Umeå University in Sweden, added: “So far, Kivimäki and colleagues’ results provide the strongest indication of a causal association between long working hours and an aspect of cardiovascular disease, namely, stroke.”
Kivimäki expects these findings might be useful to better advise patients about their heart health: “Health care professionals should advise patients who work long hours that such working pattern is associated with an increased health risk and that management of vascular risk factors is particularly important for them, that is: 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.”