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Screening For Asymptomatic Carotid Artery Stenosis
Evidence Syntheses, No. 50
Investigators: Tracy Wolff, MD, MPH, Janelle Guirguis-Blake, MD, Therese Miller, DrPH, Michael Gillespie, MD, MPH, and Russell Harris, MD, MPH.
Author Information and AffiliationsStructured Abstract
Background:
Cerebrovascular disease is the third leading cause of death in the U.S. The proportion of all strokes attributable to previously asymptomatic carotid stenosis is low. In 1996, the United States Preventive Services Task Force concluded that there was insufficient evidence to recommend for or against screening of asymptomatic persons for CAS using physical exam or carotid ultrasound.
Purpose:
To examine the evidence of benefits and harms of screening asymptomatic patients with duplex ultrasound and treatment with carotid endarterectomy (CEA) for carotid artery stenosis (CAS).
Data Sources:
MEDLINE and Cochrane Library searches (January 1994–April 2007), recent systematic reviews, reference lists of retrieved articles, and expert suggestions.
Study Selection:
English language studies were selected to answer the following: Is there direct evidence that screening with ultrasound for asymptomatic CAS reduces strokes? What is the accuracy of ultrasound to detect CAS? Does intervention with CEA reduce morbidity or mortality? Does screening or CEA result in harm? The following study types were selected: randomized controlled trials (RCT) of screening for CAS; RCTs of CEA versus medical treatment; systematic reviews of screening tests; observational studies of harms from CEA.
Data Extraction:
Studies were reviewed, abstracted, and rated for quality using predefined USPSTF criteria.
Data Synthesis:
There have been no RCTs of screening for CAS. According to systematic reviews, the sensitivity of ultrasound is approximately 94% and the specificity is approximately 92%. Treatment of CAS in selected patients with selected surgeons could lead to an approximately 5% absolute reduction in strokes over 5 years. Thirty-day stroke and death rates from CEA vary from 2.7% to 4.7% in RCTs; higher rates have been reported in observational studies (up to 6.7%).
Limitations:
There is inadequate evidence to stratify people into categories of risk for clinically important CAS. The RCTs of CEA versus medical treatment were conducted in selected populations with selected surgeons.
Conclusions:
The actual stroke reduction from screening asymptomatic patients and treatment with CEA is unknown; the benefit is limited by a low overall prevalence of treatable disease in the general asymptomatic population and harms from treatment.
Contents
- 1. Introduction
- 2. Background
- 3. Methods
- 4. Results
- Summary of Results
- Key Question 1. Is there direct evidence that screening adults with ultrasound for asymptomatic CAS reduces fatal and/or nonfatal stroke?
- Key Question 2. What is the accuracy and reliability of ultrasound to detect clinically important CAS?
- Key Question 3. For people with asymptomatic CAS 60%–99%, does intervention with CEA reduce CAS-related morbidity or mortality?
- Key Question 4. Does treatment for asymptomatic CAS 60%–99% with CEA result in harm?
- 5. Discussion
- 6. Emerging Issue - Stenting for Carotic Artery Stenosis
- 7. Research Gaps
- Appendix 1. Literature Search and Inclusion/exclusion Criteria for Key Questions
- Appendix 2. USPSTF Hierarchy of Research Design and Quality Rating Criteria
- Appendix 3. Evidence Table for Randomized Controlled Trials for Effectiveness of Surgery versus Medical Management for Asymptomatic Carotid Artery Stenosis
- Appendix 4. Evidence Table on Complications Rates for Carotid Endarterectomy
- References
Suggested citation:
Wolff T, Guirguis-Blake J, Miller T, Gillespie M, Harris R. Screening for Asymptomatic Carotid Artery Stenosis. Evidence Synthesis No. 50. AHRQ Publication No. 08-05102-EF-1. Rockville, MD: Agency for Healthcare Research and Quality, December 2007.
This general work of the U.S. Preventive Task Force (USPSTF) is supported by the Agency for Healthcare Research and Quality (AHRQ), Rockville, Maryland. This review did not receive separate funding.
The findings and conclusions in this document are those of the authors, who are responsible for its content, and do not necessarily represent the views of AHRQ. No statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services.
The information in this report is intended to help clinicians, employers, policymakers, and others make informed decisions about the provision of health care services. This report is intended as a reference and not as a substitute for clinical judgment.
This report may be used, in whole or in part, as the basis for the development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.
No investigators have any affiliations or financial involvement (e.g., employment, consultancies, honoraria, stock options, expert testimony, grants or patents received or pending, or royalties) that conflict with material presented in this report.
- Screening For Asymptomatic Carotid Artery StenosisScreening For Asymptomatic Carotid Artery Stenosis
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