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The U.S. Preventive Services Task Force (USPSTF) has reaffirmed its recommendation against screening asymptomatic adults in the general population for carotid artery stenosis, draft guidance showed.

After an updated review of the evidence, the USPSTF concluded "with moderate certainty that the harms of screening for asymptomatic carotid artery stenosis outweigh the benefits."

The recommendation against screening is consistent with the task force's previous 2007 guidance on the topic, as well as guidelines from other major organizations, including the American Heart Association/American Stroke Association and the American College of Cardiology.

Several factors contribute to the consensus that routine screening isn't a good idea.

Studies indicate that the prevalence of carotid artery stenosis is low in the general population, at 1% or lower. When stenosis is present, few cases actually trigger a stroke, and there are no reliable ways to identify the problematic cases.

The tool of choice to screen for carotid stenosis is duplex ultrasonography, and even though it has relatively high accuracy, there are still some false-positives, which can result in unnecessary follow-up testing. It will miss some cases, too.

More targeted screening is made difficult by the inability to reliably pick out the patients who are at the greatest risk for having carotid stenosis.

Even when carotid stenosis is confirmed, however, the potential interventions -- endarterectomy or stenting -- have minimal benefit, accompanied by some risks.

Previous trials in selected patients with asymptomatic carotid stenosis have shown that endarterectomy cuts the risk of stroke or perioperative death by about 3.5% in absolute terms compared with medical therapy.

But those trials were done when medical therapy was not as good as it is now, according to , director of the Duke Stroke Center in Durham, N.C., who noted that the risk of stroke with current optimal medical therapy in patients with carotid stenosis is about 1% or even lower per year.

So endarterectomy -- as well as stenting -- "may carry a lot less benefit than what we thought based on the clinical trials that were done a couple of decades ago," he told 乌鸦传媒 at the International Stroke Conference in San Diego.

The USPSTF noted that the CREST-2 trial might help address the benefits of both surgery and stenting compared with current medical therapy. That trial will compare both interventions plus intensive medical therapy to intensive medical therapy alone.

If the course of action chosen after detecting carotid stenosis is an intensification of medical therapy, there is no evidence that that is beneficial either, according to the task force.

Thus, any potential benefits to screening for and treating carotid stenosis are likely to be small, and, according to the task force, outweighed by the potential harms, which include unnecessary interventions and the risks associated with them, like stroke, death, and myocardial infarction.

"So when you put the whole thing together -- the low incidence in the general population, not being able to identify a high-risk population, the false-positives and the false-negatives of the test, the need to do additional testing, the lack of definite benefit from the interventions, plus the risks of the interventions, which are not zero -- that's what the recommendation is based on," Goldstein said.

The draft guidance and accompanying evidence review .

From the American Heart Association:

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