Abstract 8918: Diagnostic Criteria for Ultrasound Diagnosis of Internal Carotid Artery Stenosis Vary Widely Among Accredited Vascular Laboratories. A Survey from the Intersocietal Commission for the Accreditation of Vascular Laboratories (ICAVL)
Background: Carotid duplex ultrasound (DUS) is widely used for diagnosis of internal carotid artery (ICA) stenosis and therapeutic decisions are often on the basis of DUS findings. There are no universal standard DUS criteria to grade the severity of ICA stenosis. A 2003 publication from the Society for Radiologists in Ultrasound (SRU) provided consensus criteria for grading ICA stenosis, but their integration into clinical practice is unknown.
Methods: Random sample of 10% of vascular laboratories accredited in extracranial carotid testing. Data were abstracted from the ICAVL database, including most recent accreditation application. A single reviewer (HLG) compared laboratory diagnostic criteria to published references.
Results: 152 vascular laboratories were sampled, 57.2% of which were outpatient based. Mean annual carotid volume 1,330 + 124.1 studies (range 100-9,858). There were 17 diagnostic criteria in use among 117 labs with the remaining facilities utilizing locally developed (6 labs) or unreferenced or hybrid criteria (29 labs). Mean number of categories of ICA stenosis was 5.80 + .084 (range 3-12). Cut-points for the mildest disease stratum ranged from 0 to 0-60% with normal or 0% most commonly reported (67.1% of labs). The cut-point for most severe (non-occlusive) stenosis ranged from 70 to 91% with 80% most commonly reported (64.5% of labs). SRU consensus-based criteria were used in only 27.0% of laboratories, although there was a statistically significant increase in SRU utilization among labs accredited after versus before 2005 (50.0% vs. 18.8%, P <0.001). Despite divergent diagnostic criteria and severity cut-points, self-reported accuracy of DUS for diagnosis of ICA stenosis from correlation studies was high (mean 85.8 + 0.65%).
Conclusion: Diagnostic criteria and cut-points for grading severity of ICA stenosis using DUS vary widely in accredited vascular laboratories. Despite this, diagnostic accuracy is acceptable. Uptake of SRU consensus criteria has been limited, but is more common among recently accredited facilities. Health care providers must be aware of the lab-to-lab variation in reporting of ICA stenosis while further efforts to achieve consensus reporting are considered by professional societies.
- © 2011 by American Heart Association, Inc.