USPSTF Recommends Against Screening for Asymptomatic Carotid Artery Stenosis

USPSTF Recommends Against Screening for Asymptomatic Carotid Artery Stenosis
At first glance, the recommendation seems surprising — but upon further examination, it makes sense.

The U.S. Preventive Services Task Force (USPSTF) has been releasing new and updated guidelines periodically. Along with the release of this recommendation statement, the USPSTF has revised the way it grades its recommendations to make them more clinically useful.

Recommendations concern preventive care for patients without recognized signs or symptoms of a given condition. The USPSTF now grades the recommendations as follows (descriptions of levels of certainty can be found at the guidelines home page):

A — The service is recommended. High certainty that benefit is substantial.

B — The service is recommended. High certainty that benefit is moderate, or moderate certainty that benefit is moderate to substantial.

C — The USPSTF recommends against providing the service routinely. Moderate certainty that the benefit is small. Considerations may support providing the service to individual patients.

D — The USPSTF recommends against the service. Moderate to high certainty of no benefit or that the harms outweigh the benefits.

I — Evidence is insufficient to assess the balance of benefits and harms.

The USPSTF also now provides suggestions for practice: For Grade A or B recommendations, offer the service; Grade C, offer the service only based on individual considerations; Grade D, discourage the service; Grade I, if the service is offered (e.g., based on clinical considerations), patients should understand the uncertainty about the benefits and harms.

In a new guideline, the USPSTF recommends against screening for asymptomatic carotid artery stenosis in the general population. The recommendation is graded "D." The suggestion is that such screening be discouraged.

Although no randomized trials of screening have been performed, some evidence supports the USPSTF recommendation:

Carotid ultrasonography is sensitive for severe carotid stenosis (94% for stenosis 60%) but results in many false-positives.
Angiography provides accurate confirmation but is associated with serious adverse events (e.g., stroke); noninvasive testing (e.g., magnetic resonance imaging) is associated with false-positives (leading to unnecessary surgery and surgery-related stroke and death).
Carotid endarterectomy at excellent centers is associated with, at best, a 3% 30-day rate of stroke or death.
Select patients who undergo carotid endarterectomy performed by selected surgeons experience a 5% decrease in stroke or perioperative death within 5 years, according to results from two good-quality randomized trials; these benefits would be lower in the general population.
Comment: Even though the USPSTF requires the highest levels of evidence to recommend any preventive service, I was surprised by its "not recommended" stance on this one, because randomized trials of endarterectomy in asymptomatic people have suggested modest benefits (primarily in men). But it makes sense. The task force did not cite insufficient evidence as the basis for its recommendation; instead, it used randomized trial evidence, data on screening test accuracy, and projected harms from invasive procedures. We would need to screen more than 4000 people to prevent one stroke (during 5 years); in the process, for each person helped, almost as many people would be harmed by angiography consequences, perioperative stroke, or death. Despite this problematic benefit-to-harm ratio, many patients are undergoing screening carotid ultrasonography that is offered directly by private companies. However, prevention of atherosclerosis or better screening tests and treatments (and not carotid ultrasonography) will be the way to prevent stroke and death from carotid stenoses.

— Richard Saitz, MD, MPH, FACP, FASAM

Published in Journal Watch General Medicine January 15, 2008

Citation(s):
Wolff T et al. Screening for carotid artery stenosis: An update of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med 2007 Dec 18; 147:860.
Original article (Subscription may be required)
Medline abstract (Free)
U.S. Preventive Services Task Force. Screening for carotid artery stenosis: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2007 Dec 18; 147:854.
Original article (Subscription may be required)
Medline abstract (Free)

CDC Immunization Schedule Site

CDC Issues 2008 Childhood Vaccination Schedules

Vaccine Schedules CDC site

The 2008 recommended immunization schedules for children 18 years and younger have been published in MMWR.

Among the changes from 2007:

The live attenuated influenza vaccine (FluMist) is now recommended for children as young as age 2.
The meningococcal conjugate vaccine (MCV4) is recommended for high-risk children aged 2 to 10 years and all children 13 to 18 who haven't been previously immunized. (Routine MCV4 vaccination continues to be recommended for normal-risk children aged 11 to 12, as well as children through age 18 at increased risk for meningococcal disease.)
A new catch-up schedule advises that children aged 7 to 18 who received their first dose of the tetanus and diphtheria toxoids/tetanus and diphtheria toxoids and acelluar pertussis vaccine (Td/Tdap) before age 1 should be given four doses, with 4 or more weeks between the second and third doses.