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You are here: HomePublic Comments and NominationsOpportunity for Public CommentDraft Research Plan : Draft Research Plan

Draft Research Plan

Draft Research Plan for Asymptomatic Carotid Artery Stenosis: Screening

This opportunity for public comment expired on September 11, 2019 at 8:00 PM EST

Note: This is a Draft Research Plan. This draft is distributed solely for the purpose of receiving public input. It has not been disseminated otherwise by the USPSTF. 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.

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.

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In an effort to maintain a high level of transparency in our methods, we open our draft Research Plans to a public comment period before we publish the final version.

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Draft: Proposed Analytic Framework

Figure 1 is the analytic framework that depicts the four Key Questions (KQ) to be addressed in the review. The figure illustrates how screening for carotid artery stenosis may result in improved health outcomes, including reducing mortality and stroke rate as well as improving quality of life or functional status (KQ1). Additionally, the figure depicts the effects of treatment of CAS on health outcomes in a previously screened, asymptomatic population (KQ3), as well as harms associated with screening (KQ2) and treatment (KQ4).


Draft: Proposed Key Questions to Be Systematically Reviewed

  1. Is there direct evidence that screening asymptomatic adults for carotid artery stenosis (CAS) with duplex ultrasonography improves health outcomes?
  2. What are the harms associated with screening or confirmatory testing for asymptomatic CAS?
  3. For asymptomatic persons with CAS, does treatment with carotid endarterectomy (CEA) or carotid angioplasty and stenting (CAAS) provide incremental benefit beyond current standard medical therapy?
  4. What are the harms associated with CEA or CAAS for the treatment of asymptomatic CAS?

Draft: Proposed Research Approach

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 stroke or transient ischemic attacks

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

Interventions KQs 1, 2: Screening with carotid duplex ultrasonography

KQs 3, 4: CEA, CAAS

KQs 1, 2: Physical examination for carotid bruit; carotid intima-media thickness test 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

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 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.

Current as of: August 2019

Internet Citation: Draft Research Plan: Asymptomatic Carotid Artery Stenosis: Screening. U.S. Preventive Services Task Force. August 2019.

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