USPSTF Again Recommends Against Carotid Stenosis Screening

February 03, 2021

The US Preventive Services Task Force (USPSTF) has reaffirmed its 2014 recommendation against screening for asymptomatic carotid artery stenosis in the general adult population (D recommendation).

The Task Force says the decision is based on evidence that the harms of screening for carotid artery stenosis in asymptomatic adults outweigh the benefits, with no new evidence that would change the previous recommendation.

Considerations behind the decision include the effects of false positive results when screening the general population with duplex ultrasonography; inadequate evidence that screening for asymptomatic carotid artery stenosis leads to a reduction in stroke or death; and the likelihood of small to moderate harms of screening for and treatment of asymptomatic carotid artery stenosis.

The restated recommendation is also consistent with that of the 2014 guidelines from the American Heart Association not to screen low-risk populations for asymptomatic carotid artery stenosis.

The new USPSTF recommendation statement was published online in JAMA on February 2.

A JAMA Patient Page explains that the goal of screening for carotid artery stenosis is to prevent stroke and death. However, no studies have directly investigated whether screening the general population for carotid artery stenosis decreases the rates of stroke and death; and studies that compared surgical/interventional procedures for carotid artery stenosis vs medical therapy alone have shown that additional surgery/procedures result in small or no benefit in reducing stroke or death.

Because medical therapy is standard care for people who have risk factors for carotid artery stenosis, if surgery/procedures offer no additional benefit, screening is not worthwhile.

In terms of potential harms, ultrasound screening in the general population can result in high rates of false positive findings, leading to unnecessary additional testing or treatment. This can lead to potentially serious adverse effects from carotid procedures or surgery, including stroke and death, the document notes.

On the basis of current evidence, the USPSTF concludes with moderate certainty that screening for asymptomatic carotid artery stenosis in the general population has no benefit and may be harmful, the Patient Page article concludes.

A systematic review for the USPSTF, also published in JAMA with the statement, found two studies (SPACE-2 and AMTEC) published since 2014 on the comparative effectiveness of carotid revascularization plus best medical therapy compared with best medical therapy alone. Both studies were prematurely terminated and "added little to the evidence base on effectiveness of revascularization compared with best medical therapy," the authors state.

New evidence related to procedural harms from contemporary national databases and surgical registries shows a wide variation in complication rates, which may be attributable to patient and surgeon/operator selection, they add.

However, they note that several ongoing trials comparing interventional approaches to medical therapy will add to the evidence base for asymptomatic carotid artery stenosis. These include CREST-2 and ECST-2 (estimated to be completed in 2022), and ACTRIS (estimated to be completed in 2025).

The USPSTF statement is accompanied by three editorials.

In one editorial, Larry Goldstein, MD, University of Kentucky, Lexington, notes that the estimated population-attributable risk for stroke related to asymptomatic carotid artery stenosis is approximately 0.7%, a risk considerably lower than for other stroke risk factors, such as hypertension, atrial fibrillation, cigarette smoking, and hyperlipidemia.

There remains no validated risk stratification tool for identifying a subpopulation of adults in which the prevalence of asymptomatic carotid artery stenosis with a higher population-attributable risk would lead to a benefit of intervention beyond risk factor management, he reports.

Goldstein notes that population-based screening is intended to identify persons with conditions for whom there would be important health benefits from treatments that these patients would not otherwise have received had the condition not been detected. Having reviewed the evidence available, he concludes, "The currently available data clearly support the reaffirmed USPSTF recommendation against population screening for asymptomatic carotid artery stenosis."

In another editorial, Salomeh Keyhani, MD, University of California, San Francisco, and Eric Cheng, MD, University of California, Los Angeles, point out that carotid artery screening among asymptomatic patients makes carotid artery revascularization more likely, even though the benefits in stroke risk reduction are not established and the up-front risks, including stroke and death, are clear.

"The USPSTF has once again reaffirmed its message that the evidence does not support screening in the general adult population. In addition, if a patient with carotid artery stenosis is identified through imaging for other reasons, a focus on cardiovascular risk factor control is the best treatment strategy," they conclude.

In a third editorial, Rebecca Smith-Bindman, MD, and Kirsten Bibbins-Domingo, MD, University of California, San Francisco, make the point that the only way to know whether screening is beneficial would be to conduct a randomized clinical trial in which individuals who are asymptomatic or patients with cardiovascular risk factors, such as hypertension or smoking, are randomly assigned either to undergo screening or not and to then follow the patients for several years.

"Imaging for screening should be put through the same rigorous evaluation as medical treatments and surgical interventions, particularly when the imaging directly results in the use of such treatments and medications," the editorialists say.

JAMA. Published online February 2, 2021. USPSTF statement, Full text; Systematic review, Abstract; Goldstein Editorial; Keyhani and Cheng Editorial; Smith-Bindman and Bibbins-Domingo Editorial

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