Long work hours linked to cardiovascular risk

Someday, asking patients about how many hours a day they work may be a way to help predict whether they will develop heart disease.

A study in the April 5 Annals of Internal Medicine found that over time, patients who worked an 11-hour day had a 67% greater chance of developing heart disease than those who worked seven to eight hours (link).

"We were really surprised to learn that a simple measure, such as information on working hours, can improve a 10-year prediction of heart disease," said Mika Kivimaki, PhD, a study author and professor of social epidemiology in the Dept. of Epidemiology and Public Health at University College London.

Researchers looked at self-reported working hours from 7,095 men and women ages 39 to 62 in Great Britain who did not have prevalent heart disease. They also created a Framingham Risk Score that incorporates conventional risk factors such as lipid levels, blood pressure and smoking habits. A baseline medical exam took place in 1991 and 1993, with follow-ups conducted until 2004.

The information was collected as part of the British Whitehall II study, a prospective cohort study of British civil servants established in 1985 to identify characteristics of the work environment and health-related behaviors that link socioeconomic status to pathophysiologic changes and clinical disease.

"Given that working long hours is common and has increased in many developed countries in recent years, our study potentially has important implications," study authors wrote.

But Kivimaki said asking patients about work hours isn't a question physicians should incorporate yet.

"No recommendations for changes in clinical practice should be made before findings have been replicated by other studies. We need to be sure that our results are generalizable," he said.

If the results are replicated, asking patients how many hours they work and incorporating the information when measuring risks of heart disease could become standard practice, because it is simple and virtually cost-free, Kivimaki said.

"This new information may be used to improve decisions regarding preventive interventions, for example, change in diet and physical activity, and medication, such as statins, for heart disease," he said.