"Adding working hours to the Framingham risk score improved identification of persons who later developed heart disease," explained study co-author Mika Kivimaki. The Framingham risk score, aimed at gauging heart disease risk, is developed from data that includes age, sex, blood pressure level, cholesterol levels, and whether or not a patient smokes, said Kivimaki, a professor of social epidemiology at University College London.
Still, Kivimaki stressed that her team could not confirm a direct cause-and-effect relationship between putting in lots of overtime and getting heart disease.
Looking at "lifestyle factors," such as time spent working, is an increasing part of heart disease research, noted Dr. Suzanne Steinbaum, a preventive cardiologist at Lenox Hill Hospital in New York City.
"Incorporating long working hours into the [Framingham] model resulted in reclassifying low-risk patients about 4.7 percent of the time," said Steinbaum, who is also director of Women and Heart Disease at the hospital's Heart and Vascular Institute.
An example, said Steinbaum, would be a 55 year-old woman. She might be at low risk for a heart attack using the Framingham score alone, but then might be "bumped up into a higher risk category" if she worked especially long hours, Steinbaum said.
"This is important because patients in a higher-risk category would be treated more aggressively for prevention of coronary heart disease," she said.
Longer working hours are becoming more common in developed countries, the study authors noted, and that could possibly increase workers' odds for coronary heart disease. They added that prior research in Europe and Japan has shown similar links between long work hours and heart attacks, and Kivimaki said "the new information may improve decisions regarding lifestyle interventions and medication for heart disease."
While no changes should be made to patient care at this time, Kivimaki said that i
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