The review acknowledges that the harms of screening for asymptomatic carotid artery stenosis outweigh the benefits.
Overall, the USPTF recommends against screening in the general adult population and to use discretion when doing so.
This recommendation was based on evidence indicating that the harm of screening for carotid artery stenosis outweighs the benefits. In addition, there are very few studies that directly examine the health benefits of early screening and treatment.
Thus, based on all available evidence, and the limitations in noteworthy trials, the task force concluded that the magnitude of any benefit would be smaller in asymptomatic persons in the general population when compared to participants in trials.
There was little evidence to support that treating asymptomatic patients reduces adverse health outcomes such as stroke or mortality.
Additionally, prevalence of events related to carotid artery stenosis is notably low in the general population.
“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,” wrote Larry Goldstein, MD, Kentucky Neuroscience Institute, University of Kentucky, in an accompanying editorial.
The USPTF also considered the potential harms of early detection and treatment. For one, their 2014 review noted that carotid duplex ultrasonography (DUS) tends to generate many false-positive results in the screening of the general population.
Furthermore, 2 studies of patients using angiography showed that 0.4%-1.2% had strokes as a result.
Additional research, many of which were conducted during the 1990s, suggested patients who underwent carotid endarterectomy (CEA) and carotid artery angioplasty and stenting (CAS) experienced adverse events such as stroke and/or death, in addition to other perioperative harms.
The USPTF did concede that the literature is still scarce in the assessment of direct harms caused by screening with DUS.
Nevertheless, they noted that they “found no externally validated risk stratification tools that could reliably distinguish between asymptomatic persons who have clinically important carotid artery stenosis and persons who do not, or the risk of stroke related to carotid artery stenosis.”
The task force acknowledged that more trials are needed to include long-term follow-up and comparisons of CEA or CAS added to contemporary best medical therapy and contemporary best medical therapy alone.
Additionally, there remains a need for the development of valid measures that determine which individuals are at high risk for carotid artery stenosis. These same measures could also be used to stratify those at risk for stroke due to carotid artery stenosis and those who might experience harm from treatment with CEA or CAS.
“Population-based screening is intended to identify persons with conditions who would have important health benefits from treatments they would not have otherwise received if the condition were not detected,” wrote Goldstein. “The currently available data clearly support the reaffirmed USPSTF recommendation against population screening for asymptomatic carotid.”