Task Force Nixes Mass Screening for Carotid Artery Stenosis

Marlene Busko

July 07, 2014

WASHINGTON, DC — The US Preventive Services Task Force (USPSTF) today published a final recommendation advising against screening the general adult population to detect asymptomatic carotid artery stenosis (CAS)[1]. The statement is published online in the Annals of Internal Medicine and on the USPSTF website.

Ultrasound tests to detect CAS may be falsely positive. Patients may then have angiography to evaluate for stensosis, or they may have surgery—endarterectomy or angioplasty and stenting, "which all carry a high risk of stroke, heart attack, or death," task-force member Dr Jessica Herzstein (Air Products, Allentown, PA) told heartwire .

"The best way to prevent stroke and other cardiovascular disease is to focus on what we know works, which is control blood pressure and cholesterol, not smoke, stay physically active, and maintain a healthy weight and healthy diet," she noted. "There are so many people . . . whose blood pressure and cholesterol and weight are not optimally managed, and we have such good lifestyle interventions and medications; if we could optimize those, we would be doing a great deal to prevent stroke.

"We just have to remember that any test done on a healthy person can have beneficial and harmful outcomes," she added. Plaque can be dislodged during screening or subsequent interventions and surgery. "I've seen it. It's so sad. A person is relatively healthy and then has a major stroke," Herzstein said

"We should focus on screening tests that we know are effective, and this is not one of them."

This D recommendation (meaning it discourages the use of this service) applies to adults with no history of transient ischemic attack, stroke, or other neurologic signs or symptoms, and it reaffirms a statement issued in 2007.

As previously reported by heartwire , a draft recommendation from the USPSTF was made available for a month of public comment last February.

The members of the task force conducted a systematic review of evidence of screening-test accuracy and the benefits of treatment of asymptomatic CAS with surgery or medical therapy and the harms of screening and treatment.

There are no studies on the direct benefits or harms of screening for asymptomatic CAS.

Based on existing studies, they found that for the general primary-care population, the magnitude of benefit from such screening is small to none. Carotid enterectomy is associated with a 30-day stroke or mortality rate of approximately 2.4% to 6% and an MI rate of 0.8% to 2.2%. The 30-day stroke or mortality rate after angioplasty with stenting is approximately 3.1% to 3.8%.

Screening Test Unlikely to Prevent Stroke

"The available data clearly support the US Preventive Services Task Force recommendation against population screening for asymptomatic CAS," Dr Larry B Goldstein (Duke University, Durham, North Carolina) writes in an accompanying editorial[2].

The prevalence of asymptomatic CAS >70 % in the general population is very low—estimated at 0% to 3.1%, he notes. Moreover, the risk of stroke from CAS is 0.7%, which is "dwarfed" by other risk factors such as hypertension, atrial fibrillation, cigarette smoking, and hyperlipidemia.

Despite the fact that potential harm greatly outweighs potential benefit from screening for asymptomatic CAS, "such screenings are offered throughout the country in health fairs and other settings," he notes. The American Academy of Neurology advises: "Don't recommend endarterectomy for asymptomatic carotid stenosis unless the complication rate is low (<3%)." Although this may need to be revised in the future, an appropriate additional recommendation could be, "Don't perform population screening for asymptomatic carotid artery stenosis," Goldstein writes.

Until there is more definitive trial evidence about the value of screening, "potential consumers of these services should be aware that the test is unlikely to prevent them from having a stroke or to lead to improvements in their health," he cautions.

Not Like Blood Pressure or Diabetes Screening

The trials for asymptomatic carotid artery stenosis were done over a decade ago, and since then, there's been a substantial reduction in the risk of stroke largely due to preventive efforts, Dr David E Thaler (Tufts University School of Medicine Boston, MA) told heartwire .

There's a great role for surgery in patients who have a high risk of stroke from carotid stenosis, but the problem is identifying the patients with stenosis who are at high risk.

"I think, on balance, the American healthcare system intervenes on more asymptomatic patients than we need to," Thaler said. Like Herzstein, he noted, "I've certainly seen my fair share of strokes that occurred on the operating table or afterward in patients who had asymptomatic stenosis." Patients were being operated on "because it is there and so opening it up has got to be the right thing."

On the other hand, screening patients with asymptomatic CAS may have benefits in some cases. "My problem with this issue of not screening is [the task force] seems to base the recommendation on the risk from screening (unnecessary surgery); they don't address the benefit of identifying a patient" but not doing surgery on them.

"If you can tell a hypertensive, diabetic, obese, alcoholic smoker that they may have an 80% narrowing on one of their carotid arteries, there might be a benefit of the patient knowing and being more diligent [about their lifestyle habits] and taking their medications."

Nevertheless, like Goldstein, he agrees, "I don't think it's a great idea to set up ultrasound tables in shopping malls. . . . It's not like blood pressure and diabetes screening, where we know the risk is so high and the treatments are so good and they're so much better and cheap that it's worth doing."


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