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Carotid artery stenosis screening still can't be recommended in the absence of symptoms, the U.S. Preventive Services Task Force (USPSTF) concluded.

No "substantial" evidence has turned up in the years since its last D-grade recommendation against screening for asymptomatic adults , argued the group led by Alex H. Krist, MD, MPH, of Virginia Commonwealth University in Richmond.

"Using a reaffirmation process, the USPSTF concludes with moderate certainty that the harms of screening for asymptomatic carotid artery stenosis outweigh the benefits," they .

They pointed to false-positives with duplex ultrasonography in a general population with low prevalence, inadequate evidence that screening prevents stroke or death, and risk of small to moderate harms from screening for and treatment of asymptomatic cases.

"Interval studies of treatment of greater than 70% carotid stenosis continue to suggest small benefit (from carotid endarterectomy) or no benefit compared with best medical therapy (i.e., carotid stenting), and both procedures are associated with meaningful short-term harms of postoperative stroke or death, estimated as occurring in 0.5% to 5.1% of patients from the methodologically diverse studies that were reviewed," summarized Rebecca Smith-Bindman, MD, and Kirsten Bibbins-Domingo, PhD, MD, MAS, both of the University of California San Francisco, in an .

The recommendation applies to people without a history of stroke or signs or symptoms of a transient ischemic attack.

The group acknowledged that the screening higher-risk individuals. American Heart Association/American College of Cardiology concede screening as reasonable for asymptomatic patients with a carotid bruit. Both say screening can be considered with multiple risk factors for stroke or known peripheral artery disease or other cardiovascular disease.

However, Krist and colleagues disagreed: "No reliable tools are available to determine which individuals are at increased risk for carotid artery stenosis or are at increased risk of stroke when carotid artery stenosis is present."

Asymptomatic people "actually are being screened in high numbers," Smith-Bindman and Bibbins-Domingo noted, pointing to estimated numbers of 1.3 to 1.6 million annually, approaching 7% of insured seniors.

"The most common indications listed for carotid imaging in individuals who are asymptomatic was carotid bruit, an examination finding recognized in previous USPSTF reviews as having limited value for identifying stenosis," their editorial pointed out. "The second most common indication was previously documented carotid stenosis, a reminder that an often hidden harm of the initial screening is the multiple cascade of images that are then produced."

They concluded: "This new review by the USPSTF does not add new information. But perhaps it does give us a renewed opportunity to allow the science to guide us on the potential benefits and harms of screening."

During the public comment period before these final recommendations were published, respondents suggested that "new, safer procedures are now available (i.e., transcarotid artery revascularization [TCAR]) that were not reviewed and that may shift the balance of net benefit."

More research is needed on TCAR, as an ongoing registry suggested similar stroke risk as stenting but there is no randomized trial data available, Larry Goldstein, MD, of the University of Kentucky in Lexington, noted in .

The best shot at data that will shift the field is anticipated from the CREST 2 trial comparing intensive medical therapy alone or with carotid endarterectomy or stenting, noted in JAMA Neurology by Seemant Chaturvedi, MD, of the University of Maryland School of Medicine in Baltimore.

"Unlike previous trials, CREST 2 includes a rigorous approach to intensive medical treatment, including lifestyle modification," Chaturvedi wrote, noting recruitment has surpassed 1,700 patients and could be completed in 2022.

Meanwhile, "we should focus not so much on screening but instead on the completion of studies that provide meaningful data for shared decision-making between patients and clinicians," the editorial concluded.