Three recent studies indicate that the Framingham risk score goes only so far as a predictor of cardiovascular (CV) problems. The score, which is derived from data yielded by the long-running Framingham Heart Study, estimates the odds that a person aged 20-75 years who is currently free of heart disease or diabetes will suffer a heart attack or die of a CV cause within the next 10 years.
Researchers have found that in a younger person (age <50 years), lifetime CV risk is often much higher than predicted by the 10-year Framingham score. The investigators looked at the 10-year and lifetime risks for CV disease in 4,064 people aged 50 years or younger participating in the Coronary Artery Risk Development in Young Adults (CARDIA) study and the Multi-Ethnic Study of Atherosclerosis (MESA). Nearly all of the participants (91% of the CARDIA patients and 75% of the MESA patients) were at low (<10%) 10-year risk of CV disease according to the Framingham risk score. But when lifetime risk was calculated, nearly half of the patients were at high (>39%) risk (Circulation. 2009;119:382-389).
Results from a second study also suggest that clinicians should proceed with caution when it comes to interpreting the Framingham risk score. The study was composed of 738 men and women who had no coronary heart disease (CHD) but were taking statins because they were thought to be at increased risk of developing CHD based on their Framingham and National Cholesterol Education Program risk categorizations. However, coronary CT angiography showed no detectable plaque in 26% of those individuals (AJR Am J Roentgenol. 2009;192:235-243).
A third report brings the news that levels of the biomarker homocysteine more accurately identified the risk of CV mortality than the Framingham risk score in 302 elderly people (age 85 years on entry to the study) with no history of CV disease. As investigators pointed out, Framingham risk scores have been validated only for people up to age 75 years but are often used in older populations since there are no appropriate alternatives (BMJ. 2009;338:a3083). Over the course of five years, homocysteine levels proved to be better than the classic risk factors of Framingham at pinpointing those at high risk of CV mortality. Only 12 of the 35 study participants who died of CV disease were classified as high-risk by Framingham score, but 20 were classified as high-risk by homocysteine measurement.