Final Research Plan

Asymptomatic Carotid Artery Stenosis: Screening

November 14, 2019

Recommendations made by the USPSTF are independent of the U.S. government. They should not be construed as an official position of the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.

The final Research Plan will be used to guide a systematic review of the evidence by researchers at an Evidence-based Practice Center. The resulting Evidence Review will form the basis of the USPSTF Recommendation Statement on this topic.

The draft Research Plan was available for comment from August 15 until September 11, 2019 at 5:00 p.m., ET.

  1. Is there direct evidence that screening for carotid artery stenosis (CAS) with duplex ultrasonography in asymptomatic adults improves health outcomes?
  2. What are the harms associated with screening or confirmatory testing for asymptomatic CAS?
  3. Does surgical repair provide incremental benefit beyond current medical treatment for asymptomatic persons with CAS?
  4. What are the harms associated with surgical repair of asymptomatic CAS?

The Research Approach identifies the study characteristics and criteria that the Evidence-based Practice Center will use to search for publications and to determine whether identified studies should be included or excluded from the Evidence Review. Criteria are overarching as well as specific to each of the key questions (KQs). The update for this topic will be conducted using rapid synthesis procedures, as described in Section 4.7 of the USPSTF Procedure Manual (available at

  Included Excluded
Populations KQs 1, 2: Unselected or community-dwelling, generally asymptomatic adults (i.e., without neurologic symptoms referable to the carotid artery or a history of a stroke or transient ischemic attack)

KQs 3, 4: Unselected or community-dwelling, generally asymptomatic adults with clinically important CAS (defined as 60% to 99% stenosis)

All KQs: Children and adolescents; symptomatic adults with CAS; adults with history of a stroke or transient ischemic attack

KQs 1, 2: Persons with known carotid occlusion, with known CVD; who are undergoing CAS testing for preoperative planning, or who have had CEA or CAAS and are undergoing surveillance for restenosis

Interventions KQs 1, 2: Screening with carotid duplex ultrasonography

KQs 3, 4: Surgical repair including CEA or CAAS; transcarotid artery revascularization

KQs 1, 2: Physical examination for carotid bruit; carotid intima-media thickness for CVD risk prediction
Comparisons KQs 1, 2: No screening

KQ 3: Medical treatment/usual care (e.g., statins, antiplatelet medications)

KQ 4: Medical treatment/usual care or noncomparative studies reporting rates of harms

KQs 3, 4: Comparative studies of CEA vs. CAAS
Outcomes KQs 1, 3: CAS-related stroke, mortality, quality of life, functional status, or cognitive status

KQ 2: Adverse outcomes related to screening tests or subsequent confirmatory testing (i.e., angiography)

KQ 4: Perioperative complications (e.g., stroke, mortality, myocardial infarction, cranial nerve injuries)
KQs 1, 2: Diagnostic accuracy; CVD risk prediction
Study designs KQs 1–3: Randomized, controlled trials

KQ 4: Randomized, controlled trials; large cohort studies or registries

All KQs: Cost-effectiveness analyses

KQs 1–3: All study designs other than randomized, controlled trials

KQ 4: Case reports; small observational studies
Countries Studies conducted in countries categorized as “very high” on the Human Development Index (as defined by the United Nations Development Programme)  
Language English only Non-English languages
Years 2014 to present Publications prior to 2014

Abbreviations: CAAS: carotid angioplasty and stenting; CAS: carotid artery stenosis; CEA: carotid endarterectomy; CVD: cardiovascular disease; KQ: key question.

The draft Research Plan was posted for public comment on the USPSTF website from August 15 to September 11, 2019. The USPSTF received comments regarding the selection of outcomes, the importance of high-risk populations, and the presence of ongoing research in this area. Based on public comment, the USPSTF modified the Research Plan to indicate that all types of surgical repair will be considered and that cognitive function will be included as an outcome. The USPSTF recognizes the importance of assessing the benefits and harms of screening in high-risk populations, but will focus this update on unselected, generally asymptomatic adults in primary care settings.