Work Days of 11 Hours Boost Risk for Heart Disease, Study Says

Working overtime may be a killer, according to research that finds long hours on the job is a heart risk along with smoking, bad cholesterol and high blood pressure.

Adults who worked 11 hours a day or more had a 67 percent higher risk of developing coronary heart disease than those who worked an 8-hour shift, a study today in the Annals of Internal Medicine found. The researchers found that by adding working hours to a standard heart risk assessment model they could increase the accuracy of heart disease predictions by 5 percent.

Because working long hours is common and on the rise in developed countries, the study may have implications for doctors when it comes to advising patients on their health, said Mika Kivimaki, the lead researcher. Heart disease is the leading killer in the U.S. for women and men, according to the National Institutes of Health.

“Current evidence on coronary heart disease prevention emphasizes the importance of focusing on the total risk rather than single risk factors,” said Kivimaki, a professor at University College London, in an April 1 e-mail. “People who work long hours should be particularly careful in following healthy diets, exercising sufficiently and keeping their blood pressure, cholesterol levels and blood glucose within healthy limits.”

If today’s findings are confirmed in other trials, doctors will have another tool to help them determine who is at greater risk for heart disease, Kivimaki said.

Artery Plaque

Heart disease is usually caused by plaque building up on the walls of the arteries of the heart and can cause chest pain, shortness of breath and heart attack, according to the NIH. Those with high cholesterol, high blood pressure and chronic kidney disease, as well as people who smoke, are at higher risk for developing the condition.

Srihari Naidu, director of the Cardiac Catheterization Laboratory at Winthrop University Hospital in Mineola, New York, said these findings show that how a person lives --their stress levels, sleeping, eating and exercise habits -- can affect their risk for heart disease.

“It teaches us that we should actually be more careful if we’re going to work that long, that we should take breaks to do exercise and concentrate even more heavily on the types of food we’re eating,” said Naidu, who wasn’t an author of today’s paper, in an April 1 telephone interview. “The choices we make in our lifestyle may have consequences.”

The research followed 7,095 civil service workers in London who were ages 39 to 62 at the start of the trial. They were screened for heart disease every five years. The study found that 192 people developed heart disease over 12.3 years of follow up. Those who worked 10 hours a day had a 45 percent higher risk of heart disease than those who worked 7 to 8 hours.

To contact the reporter on this story: Nicole Ostrow in New York at nostrow1@bloomberg.net.

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net

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