A person's lifetime risk of getting heart disease may be much higher than previously thought, according to a major US study published on Wednesday.
A single risk factor -- such as smoking, having diabetes, high blood pressure or elevated cholesterol -- can significantly boost one's likelihood of having a heart attack or stroke at some point in life.
However, most studies to date have focused on how such risks play out over the short term, such as five to 10 years, giving an unrealistic picture of the longer term, said the study in the New England Journal of Medicine.
"The risk factors we develop in younger and middle ages are going to determine our heart disease risk across our lifetime," said lead author Jarett Berry, assistant professor of internal medicine at University of Texas Southwestern Medical Center.
"The current approach to heart disease prevention focuses on only short-term risks, which can give a false sense of security, particularly to individuals in their 40s and 50s."
The study drew data from 254,000 participants in the Cardiovascular Lifetime Risk Pooling Project, which measured risk factors for black and white men and women at ages 45, 55, 65 and 75.
People with multiple risk factors had higher lifetime risks for heart disease -- as much as 10 times the rates of those without risk factors.
One key finding was that healthy men age 45 have a 1.4 percent risk of a heart attack or stroke in their life, while men the same age who have two or more risk factors have a 49.5 percent risk.
Among women, the baseline risk for healthy 45-year-olds was 4.1 percent, while those with two or more risk factors saw that risk rise to 30.7 percent.
"We are giving incomplete and misleading risk information if we only focus on the next 10 years of someone's life," said principal investigator Donald Lloyd-Jones, associate professor of preventive medicine at Northwestern University Feinberg School of Medicine.
"With even just one risk factor, the likelihood is very large that someone will develop a major cardiovascular event that will kill them or substantially diminish their quality of life or health."
Lloyd-Jones added that maintaining optimal risk factors through middle age had a dramatic effect on the remainder of a person's life. "It appears that the whole is greater than the sum of the parts," he said.
An optimal risk factor profile meant the person did not smoke and did not have diabetes, had total cholesterol of less than 180 milligrams per deciliter and untreated blood pressure of less than 120 over less than 80.
The study was funded by the National Heart, Lung and Blood Institute.