People who work more than 55 hours/week are at significantly higher risk of heart disease and stroke than people who work the typical 35-40 hours/week, according to a Joint Estimates by the World Health Organization (WHO) and International Labour Organization (ILO) which evaluated the evidence using the Navigation Guide systematic review method developed by the University of California, San Francisco Program on Reproductive Health and the Environment.
The WHO/ILO Joint Estimates of global, regional, and national exposure to long working hours examined data from 194 countries and found a 17% increase in risk of heart disease and a 35% increase in risk of stroke from working more than 55 hours/week. About 9% of the world’s population works more than 55 hours/week.
“This study shows that working long hours is one of the biggest burdens of disease in the world,” said Tracey J. Woodruff, Professor and Director of the University of California, San Francisco Program on Reproductive Health and the Environment and a technical advisor on the WHO/ILO Joint Estimates. “Long working hours is killing more people than cancer.”
The study was based on 2,300 labor surveys from around the world which showed that 488 million people or 8.9% of the global population were exposed to working long hours in 2016 and nearly 750,000 deaths from heart disease and stroke were attributable to working long hours.
“Studies like this cannot happen without good science and rigorous systematic review methods,” said Woodruff. “This type of evidence is critical to decision-making and protecting public health.”
Scientists evaluated the quality of evidence and drew conclusions using the Navigation Guide systematic review method. The method evaluates evidence based on low, moderate, and high quality. It found the level of evidence on health risks of working more than 55 hours to be moderate quality.
“The Navigation Guide method allows us to make decisions based on the evidence we have. Moderate quality in this case is good. It means there is sufficient evidence for the finding,” said Woodruff.