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Should patients be screened for asymptomatic carotid artery stenosis?
1Department of Surgery, Ottawa General Hospital, University of Ottawa, ON.
Objective:
To evaluate, against published guidelines, the potential role of screening to reduce the risk of stroke and death from asymptomatic carotid artery stenosis (ACAS).
Data Sources:
Papers selected for review were identified through a GRATEFUL MED literature search, from personal files and from references documented in identified papers.
Study Selection:
Population studies concerning disease prevalence, natural history studies related to risk of stroke, randomized controlled trials related to carotid endarterectomy and natural history studies related to the risk of developing ACAS were considered for review.
Data Extraction:
An estimate was made of the potential for stroke resulting from ACAS in the general population. This was evaluated against the positive predictive value of duplex scanning, and the number of patients needing to be screened to prevent a stroke was estimated.
Data Synthesis:
The prevalence of ACAS in the general population was estimated to range from 2% to 8% for ACAS 50% or greater and to range form 1% to 2% for ACAS 80% or greater. The yearly risk of stroke or death from undetected ACAS was estimated to be 0.16% for ACAS 50% or greater and 0.06% for ACAS 80% or greater. The estimated number of patients needing to be screened to prevent 1 stroke would range from 850 to 1700 (and potentially as high as 8500).
Conclusions:
General screening for ACAs to prevent stroke and death cannot be recommended when evaluated against guidelines. The decision to screen individual patients will require judgement, continued evaluation and surveillance of the results of such screening by the treating physician.