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The ankle-brachial index (ABI), high-sensitivity C-reactive protein (CRP), and coronary artery calcium don't have enough evidence to be recommended for routine addition to traditional cardiovascular risk assessment in asymptomatic adults, according to the U.S. Preventive Services Task Force (USPSTF).

The of an "I" grade of insufficient evidence for those non-traditional risk assessment tools in people without symptoms or a history of cardiovascular disease mirrored the draft recommendations issued in January and both prior times the group considered it.

A came to the same conclusion for use of ABI in screening asymptomatic people for peripheral artery disease and cardiovascular risk.

The writing group for both, led by Susan Curry, PhD, University of Iowa in Iowa City, emphasized in Journal of the American Medical Association papers that the main problem for the non-traditional risk factors was lack of data on clinical impact.

An evidence review published in the same journal turned up "adequate evidence" of "small improvements in discrimination and risk reclassification" but it wasn't clear if the additional information above and beyond traditional risk factors, "in existing CVD risk assessment models, leads to reduced incidence of CVD events or mortality."

The Task Force recommended use of the for risk assessment, while acknowledging its limitations in over- and under-estimation of risk for some groups.

While the American Heart Association, American College of Cardiology, and some other bodies recommend that the non-traditional risk factors can be considered to help guide decisions for borderline or unclear risk assessment patients, the USPSTF argued that it "did not find convincing evidence" of a reclassification benefit in intermediate-risk groups.

The AHA and ACC also back ABI screening for higher-risk patients, including those 65 or older, 50 or older with atherosclerosis risk factors or a family history of PAD, and under 50 with diabetes and another risk factor for atherosclerosis. But, the evidence on PAD screening in high-risk, asymptomatic populations was limited, "with no compelling evidence to support differential screening or treatment in subpopulations at greater risk."

"In addition, patients in higher-risk groups (such as persons with diabetes and older adults) would likely already be candidates for interventions based on their global CVD risk, raising concern about the clinical significance of screening for additional risk factors (ie, asymptomatic PAD)," the USPSTF wrote.

An cautioned that these conclusions "should not be misconstrued as a determination that PAD is not common, clinically important, or associated with significant adverse outcomes."

Rather, undiagnosed PAD usually is accompanied by exertional leg symptoms, so a careful history for older people is likely the key to significantly improve PAD detection and treatment, concluded editorialists Mary McDermott, MD, of Northwestern University in Chicago, and Michael Criqui, MD, MPH, of the University of California San Diego.

Many comments received by the Task Force after the draft was released supported a separate positive recommendation for adding the coronary artery calcium score to traditional risk factor assessment, but again the USPSTF said it found "inadequate evidence that this change would translate into improved health outcomes among asymptomatic patients."

For the overall population, that makes sense, agreed an by John Wilkins, MD, and Donald Lloyd-Jones, MD, both of Northwestern, but these editorialists questioned its application in clinical practice.

"These conclusions are understandable from the policy perspective but do not fully address the issues faced by individual patients and clinicians in decisions about the relative merits of primary preventive therapies," they wrote.

They argued that there is good evidence for a selective, serial testing approach in appropriate patient subgroups to effective reclassify many patients to high or low risk.

"These USPSTF recommendations should spur ascertainment of the data needed to turn I statements into more definitive recommendations, specifically regarding the use of CAC measurement," they concluded.