Carotid Ultrasound Often Unnecessary

April 29, 2016

Most carotid ultrasounds for asymptomatic patients are not based on appropriate criteria.

The majority of carotid imaging tests for asymptomatic patients who undergo revascularization were performed for inappropriate indications, according to a study published in JAMA Internal Medicine.

Researchers from California, Indiana, Texas, Nebraska, and Washington performed a retrospective cohort study to gain a better understanding of why asymptomatic patients who undergo revascularization receive initial carotid imaging.

The study included 4,127 patients (98.8% male) from the Veterans Health Administration. All were 65 years or older (mean age 73.6) and had undergone carotid revascularization for asymptomatic carotid stenosis between 2005 and 2009. The researchers reported the frequency of indications and appropriateness of initial carotid ultrasound imaging for patients within each rating category after the intervention was reported. Each ultrasound could have more than one indication.

The researchers compared indications to national guidelines. They then compared the indications found in the medical records to quality assessments made by their expert panel. The sample was then restricted to 4,063 patients, who had at least one indication listed for their carotid ultrasound. If the researchers found that there were multiple indications for a patient’s ultrasound, the rating of the test was assigned on the basis of the most appropriate indication or indications. They then calculated percentages of carotid ultrasounds rated appropriate, uncertain, or inappropriate. The five-year overall survival in patients who received carotid imaging and subsequent medical record–confirmed revascularization among the three was also compared.  

The results showed that there were 5,226 indications for 4,063 carotid ultrasounds in this group. There were 1,578 listed for carotid bruit (30.2% of indications) and 1,087 for follow-up for carotid disease (stenosis/history of carotid disease) in patients who had previously documented carotid stenosis (20.8% of indications). Multiple vascular risk factors were the next most common indication listed. According to the researchers, 227 (5.4%) of indications were appropriate, 3,387 (83.4%) were uncertain, and 458 (11.3%) were inappropriate. Dizziness/vertigo and syncope were among the most common inappropriate indications.

Among the 4063 patients, 3,373 (83.0%) received a carotid endarterectomy and overall, 663 procedures were performed in patients 80 years and older. Post intervention survival was71.4% at five years. Rates of survival by age group were:

65 years to 74 years: 75.3% (1857 patients)

75 years to 84 years: 66.5% (979 patients)

85 years and older: 58.9% (73 patients)

The researchers noted that the rates of survival among patients who received carotid imaging on the basis of appropriate, uncertain, and inappropriate indications were not significantly different.

“Carotid bruit and follow-up for carotid disease accounted for approximately half of all indications provided by physicians for carotid testing,” the researchers concluded. “Strong consideration should be given to improving the evidence base around carotid testing, especially around monitoring stenosis over long periods and evaluating carotid bruits. Targeting carotid ultrasound ordering with decision support tools may also be an important step in reducing use of low-value imaging.”