Should new risk factors such as coronary artery calcium (CAC) and ankle-brachial index (ABI) be added to traditional risk factors for assessing which patients might be at risk of peripheral arterial disease and cardiovascular disease? Not so fast, according to the U.S. Preventive Services Task Force (USPSTF).
In a January 16 statement, the USPSTF noted that currently, traditional risk factors such as the Framingham risk score and Pooled Cohort Equations (PCE) are used to determine whether a patient needs treatment by modifying risk factors to prevent a cardiovascular event such as a stroke or heart attack.
But researchers have proposed that these could be supplemented by other models that could also help predict cardiovascular events, such as CAC, ABI, and another nontraditional risk factor, high-sensitivity C-reactive protein (hsCRP) measurements. So the USPSTF in 2015 launched a review to evaluate whether CAC, ABI, and hsCRP should be added to the traditional scores, because "prior evidence reviews identified them as the most promising" of nontraditional risk factors.
However, the USPSTF said it has not found sufficient evidence to evaluate the benefits and harms of adding the three nontraditional risk factors to the current basket of traditional risk factors for assessing which asymptomatic patients might be at risk of cardiovascular events.
The task force noted that a number of studies have already demonstrated an association between the three nontraditional risk factors and cardiovascular outcomes, so additional association studies aren't likely to add more information. In addition, studies assessing the new risk factors on their own are of limited value, as current treatment decisions are based on Framingham and PCE.
Instead, what is needed are high-quality studies that evaluate the addition of the nontraditional risk factors to the traditional risk factors and the resulting effect on patient outcomes, the USPSTF said. More studies are also needed to evaluate diverse patient populations.
The USPSTF noted in its statement that there are also potential harms to increased use of the nontraditional risk factors, such as radiation dose from the CT scans required to acquire CAC scores, or false-positive results that might result in additional downstream costs such as angiography.
The new recommendation will replace the task force's 2009 recommendation. The only major change with the proposed new recommendation is that PCE was used in addition to Framingham as a traditional risk factor system, and the new evaluation focused only on the three nontraditional risk factors.
The USPSTF is taking comments on the proposal through February 12 on its website.
