The U.S. Preventive Services Task Force (USPSTF) determined that there isn't enough evidence to back non-traditional risk factors, such as ankle-brachial index and C-reactive protein, to help assess cardiovascular or peripheral vascular risk in patients without obvious signs or symptoms.
The group issued two draft statements of insufficient evidence for a recommendation. Specifically, the reviews dealt with:
- Screening for peripheral artery disease (PAD) and cardiovascular disease (CVD) risk with the ankle-brachial index (ABI) in asymptomatic adults
- Adding the ankle-brachial index, high-sensitivity C-reactive protein (hsCRP), or coronary artery calcification (CAC) score to traditional risk assessment for cardiovascular disease in asymptomatic adults to prevent events
The ankle-brachial index had "adequate" evidence for accuracy in detecting symptomatic PAD but not for asymptomatic people. And for asymptomatic cases, the USPSTF's systematic review didn't turn up good evidence that screening and treating PAD could prevent progression of the disease or cardiovascular events.
There's plenty of data to support better calibration, discrimination, and reclassification of cardiovascular disease risk with the non-traditional risk factors compared with the traditional Framingham Risk Score and the Pooled Cohort Equations, the Task Force noted. And a "number of guidelines, including those from the American College of Cardiology and the American Heart Association, recommend considering hsCRP, ABI, or CAC score to clarify treatment decisions for patients whose risk assessment is borderline or unclear using a traditional risk assessment model," it acknowledged.
However, the evidence was scant (and direct evidence from adequately-powered trials nonexistent) to prove whether treatment decisions guided by addition of the non-traditional factors to traditional risk models would reduced incidence of CVD events or mortality -- leading to the "I" recommendation.
Both draft recommendations were reiterations of prior final recommendations from the USPSTF, on ankle-brachial index screening for peripheral disease in 2013 and nontraditional risk factors for cardiovascular risk assessment in 2009. Both will be through Feb. 12.