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 PS60. Predictive Multivariate Regression to Increase the Specificity of Carotid Duplex for High-grade Stenosis

​Jonathan J. Stone, Adam J. Doyle, Anthony Carnicelli, Sean J. Hislop, Michael Singh, Jason Kim, Jennifer L. Ellis, Nicholas J. Gargiulo, David L. Gillespie, Ankur Chandra
University of Rochester, Rochester, NY.

OBJECTIVES: Duplex ultrasound is the most commonly performed diagnostic modality for the detection of carotid artery stenosis. This noninvasive technique has excellent sensitivity but can sometimes lead to a false positive diagnosis of severe stenosis and subsequently unwarranted endarterectomy. We therefore aimed to improve the specificity of duplex ultrasound for high-grade stenosis.

METHODS: A retrospective review was performed for patients who underwent both carotid duplex ultrasound and CTA between 2000 and 2009. The NASCET technique was used to calculate percent stenosis and duplex ultrasound velocities were recorded. A logit regression model was built to predict severe stenosis using the combination of peak systolic velocity (PSV), end-diastolic velocity (EDV), and the ratio of PSV at stenosis to PSV at the common carotid.

RESULTS: A total of 610 vessels were analyzed yielding 31 data points for severe and 579 for <80% stenosis. Index values were calculated for each carotid duplex combination using the logit formula generated by the model (-6.413+PSV*0.00851+EDV*0.0224+Ratio*-0.1166). The calculated logit regression formula was transformed to probabilities using 1/(1+(exp(-index))). This yielded a specificity of 97.7% when tested against this population.

CONCLUSIONS: A formula incorporating PSV, EDV and ratio produced a very high specificity of duplex ultrasound for the prediction of carotid artery stenosis. It is suggested that this tool be used in conjunction with current duplex criteria to increase testing accuracy. This tool may help to identify those asymptomatic patients who may benefit from continued medical therapy over surgical intervention.

AUTHOR DISCLOSURES: A. Carnicelli, Nothing to disclose; A. Chandra, Nothing to disclose; A. J. Doyle, Nothing to disclose; J. L. Ellis, Nothing to disclose; N. J. Gargiulo, Nothing to disclose; D. L. Gillespie, Nothing to disclose; S. J. Hislop, Nothing to disclose; J. Kim, Nothing to disclose; M. Singh, Nothing to disclose; J. J. Stone, Nothing to disclose.

Posted April 2012

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