Study Shows Latest Method for Predicting Heart Disease Risk Is Accurate
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Reviewed By Louise Chang, MD
Feb. 16. 2010 -- New guidelines for predicting women's heart disease risk, updated in 2007 by the American Heart Association (AHA), work well, according to researchers who put the new strategy to the test.
The guidelines recommend a simplified approach to assessing a woman's heart disease risk, categorizing it as high risk, at-risk, or optimal risk.
The researchers evaluated how well the guidelines worked by testing them with participants in the Women's Health Initiative (WHI), which enrolled more than 160,000 women, ages 50 to 79. Next, they compared it to a commonly used approach for predicting cardiovascular disease risk from the long-running Framingham Heart Study.
"The advantage to the 2007 AHA guideline is that it's simple," says study researcher Judith Hsia, MD, director of clinical research at AstraZeneca, who conducted the study while a professor of medicine at George Washington University in Washington, D.C.
"One drawback is, it's only for women," she says, although "there is no reason it shouldn't work for men."
Hsia and colleagues categorized the women from the WHI study as high risk, at-risk, or optimal or low risk, depending on risk factors. (The WHI study evaluated the effect of hormone therapy, diet, calcium, and vitamin D on heart disease and cancers.) Here are the characteristics of each category:
- High-risk women have known cardiovascular disease, diabetes, or end-stage or chronic kidney disease.
- At-risk women have more than one major risk factor for heart disease (such as cigarette smoking, poor diet, inactivity, obesity, family history of early heart disease, high blood pressure or cholesterol, evidence of "subclinical" vascular disease, metabolic syndrome, or poor treadmill test results).
Optimal or low-risk women have a healthy lifestyle and no risk factors. A healthy lifestyle included exercising the equivalent of 30 minutes of brisk walking six days a week and eating less than 7% of total calories from saturated fat.
The Framingham Heart Risk Method
Hsia's team compared the new AHA approach to one commonly used approach from the Framingham Heart Study, a long-running study of heart disease launched in 1948, that uses seven characteristics to compute the predicted risk of heart problems over the next 10 years:
- Total cholesterol
- HDL "good" cholesterol
- Systolic blood pressure (upper number)
- Need for blood pressure medication
- Cigarette smoking
For instance, a woman who is 50 with healthy cholesterol levels (175 total and 60 HDL), doesn't smoke, is on blood pressure medication, and keeps systolic pressure at 120 would have a 10-year risk of 1% for heart attack or coronary death.
Those categorized as high-risk using this method have a 10-year risk of more than 20% and a history of heart disease or diabetes.
Testing the AHA Guidelines
Hsia and her colleagues found that 11% of the WHI participants were high risk, 72% were at risk, and 4% at optimal or low risk using the AHA guidelines.
Another 13% could not be categorized as they lacked risk factors but didn't have good lifestyle habits. That group may need to be addressed in future version of the guidelines, says Hsia.
At the follow-up about eight years later, women in the high-risk group were more likely to have a heart attack or die of coronary disease than were the lower-risk women. While 12.5% of the high-risk women had a heart attack or died from heart disease, 3.1% of the at-risk women did, and just 1.1% of the optimal-risk women did over 10 years.
When Hsia's team compared the new guidelines with the Framingham risk prediction, they found the new guidelines predicted heart problems with accuracy similar to the Framingham categories of less than 10%, 10% to 20%, and over 20%.
The AHA guidelines were less accurate, however, than another Framingham approach, which uses risks of less than 5%, 5% to 20%, and over 20%.
The new guideline, however, "is more accessible," Hsia says. "It's easier for practitioners to use, easier for patients to understand. I am not saying this [AHA] guideline is preferable to Framingham, but it's worth considering," Hsia tells WebMD.
Based on the risk category, a doctor can then work with the woman to control or eliminate the risk factors.
"This study is an important validation study to confirm the predictive accuracy of the risk stratification approach," says Cynthia Taub, MD, director of noninvasive cardiology at Montefiore Medical Center in New York.
One strength, she says, is the large number of participants and the relatively long follow-up.
Whether a woman's doctor uses the AHA guideline or the Framingham approach, Taub says it's important that women know their risks. "If you have known coronary artery disease, diabetes, or end-stage or chronic renal [kidney] disease, you are in the high-risk group," she tells patients.
Many risk factors are modifiable, she says, such as smoking, not exercising, and poor diet.
"Stop smoking, become active, improve your diet, and discuss with your doctor how to effectively manage your hypertension and high cholesterol," she advises.
SOURCES: Hsia J. Circulation: Cardiovascular Quality and Outcomes, March
Judith Hsia, MD, director of clinical research, AstraZeneca, Wilmington, Del.
Cynthia Taub, MD, director of noninvasive cardiology, Montefiore Medical Center, New York.
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