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[Interobserver variation in ultrasonographic scanning of carotid stenosis]
Peter Kristian Kofoed1, Steen Christian Kofoed, Marie-Louise Moes Grønholdt
1Karkirurgisk Afdeling B, Amtssygehuset i Gentofte. peter_kofoed@hotmail.com
Introduction:
Ultrasonic carotid interna scanning is today the gold standard for diagnosing carotid stenosis in patients with stroke or transient ischemic attack. The procedure of ultrasonic carotid interna scanning is not a well-defined procedure. Knowledge of the reproducibility of the method used in own department is important in order to evaluate its usefulness.
Material And Methods:
Interobserver variability of ultrasonic, duplex carotid artery scanning was examined in 68 carotid arteries in 35 patients by two experienced technologists. The two observers were compared using the kappa (kappa) statistics to analyse the agreement beyond chance.
Results:
kappa was 0.70 (CI: 0.56-0.83) when the stenoses were categorised in the intervals 0-14%, 15-49%, 50-69%, 70-79%, 80-99% and occlusion. Categorising the stenosis in the clinically relevant intervals 0-69%, 70-79% and occlusion which are used to determine if the patient is a candidate or not to carotid endarterectomy yielded a kappa = 0.92 (CI: 0.81-1.00).
Discussion:
Low level stenosis accounted for most variability. If state-of-the-art ultrasonic equipment and experienced technologists are used a high level of reproducibility can be achieved.