Jan. 25, 2012 -- The method doctors use to determine a person's risk for heart disease could underestimate the future odds of heart attack and stroke.
That's because a person's risk of heart disease is currently estimated in the short-term, meaning the likelihood of having heart disease in the next 10 years.
But a new study calculates lifetime risk by measuring it across the adult age spectrum, beginning in middle age. This research estimates risks for men and women, and for African-Americans and whites. Previous estimates of heart disease have looked mainly at white men.
By using lifetime estimates of heart disease risk, this research provides a long-term view of the extent of the health problem in the U.S. now and in the future, researchers at Northwestern University say.
They argue that a short-term glimpse of risk may give some adults a false sense of security about their lifetime prospects of heart disease. The study found that a 45-year-old man or woman who is at low risk for heart disease in the next decade may be at very high risk later in life if he or she has just one or two risk factors, such as higher-than-ideal blood pressure or cholesterol levels.
"We are giving incomplete and misleading risk information if we only focus on the next 10 years of someone's life," study researcher Donald Lloyd-Jones, MD, says in a news release. He is an associate professor of preventive medicine at Northwestern University Feinberg School of Medicine in Chicago.
"With even just one risk factor, the likelihood is very large that someone will develop a major [heart or stroke] event that will kill them or substantially diminish their quality of life," says Lloyd-Jones.
The study is published in the New England Journal of Medicine.
Lifetime Risk for Heart Disease
To determine lifetime risk, the researchers analyzed data from more than 250,000 adults at ages 45, 55, 65, and 75 over a 50-year period. They considered four key risks: blood pressure, cholesterol level, smoking, and diabetes.
An ideal risk-factor profile was a person who:
- Had total cholesterol less than 180 milligrams per deciliter
- Had blood pressure less than 120 / less than 80, without taking blood pressure medication
- Was a non-smoker
- Did not have diabetes
Researchers found that a 55-year-old man's risk of dying through age 80 from heart disease or stroke was 4.7% if all risk factors were ideal, 18.4% if he had one major risk factor for heart disease, and 29.6% if he had two or more major risk factors.
By age 75, his risk of dying from heart disease or stroke was 20.7% when all risk factors were ideal, but nearly 40% with two or more risk factors.
For a 55-year-old woman, her risk of dying from heart disease or stroke was 6.4% if all risk factors were ideal, 11.4% if she had one risk factor, and 20.5% if she had two or more risk factors.
The study also found that African-Americans had more risk factors for heart disease or stroke, compared to whites. But because African-Americans also tend to die at a younger age, they had a similar lifetime risk of having a heart attack or stroke.
Although treating existing risk factors reduces a person's chances of heart disease, what's key is preventing them in adults for as long as possible through a heart-healthy lifestyle -- by eating healthy, exercising regularly, and not smoking.
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