Institutional Differences in Carotid Artery Duplex Diagnostic Criteria Result in Significant Variability in Classification of Carotid Artery Stenoses and Likely Lead to Disparities in Care

Abstract

Background-The indications for carotid revascularization are based almost exclusively on the results of carotid duplex ultrasonography. Noninvasive vascular laboratories show large variation in the diagnostic criteria used to classify degree of carotid artery stenosis. We hypothesize that variability of these diagnostic criteria causes significant variation in stenosis classification directly affecting the number of revascularizations and associated costs. Methods and Results-The diagnostic criteria to interpret carotid duplex ultrasounds were obtained from 10 New England institutions. All carotid duplex scans performed at our institution were reviewed from 2008 to 2012. Using the diagnostic criteria from each institution, the degree of stenosis that would have been reported was classified as 70% to 99% asymptomatic, 80% to 99% asymptomatic, and 50% to 99% symptomatic. We then calculated the theoretical number of carotid revascularization procedures that this cohort would be offered using each institution's diagnostic criteria and the costs of these procedures based on reimbursement rates. Among 10 614 patients who underwent 15 534 carotid duplex scans, 31 025 arteries were reviewed. Application of the 10 institutions' criteria to the patients from our institution yielded marked variation in the number classified as 70% to 99% asymptomatic (range, 186-2201), 80% to 99% asymptomatic (range, 78-426), and 50% to 99% symptomatic (range, 157-781). If revascularizations were based on these results, costs would range from $2.2 to $26 million, $0.9 to $5.0 million, and $1.9 to $9.2 million, respectively. Conclusions-Differences in diagnostic criteria to interpret carotid ultrasound result in significant variation in classification of carotid artery stenosis, likely leading to differences in the number and subsequent costs of revascularizations. This theoretical model highlights the need for standardization of carotid duplex criteria. (Circ Cardiovasc Qual Outcomes. 2014;7:423-429.)

Carotid endarterectomy should not be based on consensus statement duplex velocity criteria

“…Counterintuitively, though, the way in which the percent-age of stenosis is determined is widely variable and inconsistent. 19,20,34–36 More than three decades ago, Strandness et al 37 first established a set of CDUS velocity criteria for use in clinical practice. These criteria were widely accepted as an alternative to the previous mechanism of invasive angiography.…”

“…Since its inception, CDUS velocity criteria have undergone a multitude of permutations in an attempt to advance its use in clinical practice. 14,19,38–40 Although well intentioned, these permutations have had the undesired result of wide variation between centers. This was clearly documented by Arous et al, 19 and has led to an environment where, based on local CDUS criteria, a patient may be offered revascularization at one institution or enter surveillance at another only 10 to 20 miles apart.…”

“…22 Our CDUS criteria for ≥80% stenosis are ICA PSV ≥430 cm/s, end-diastolic velocity ≥151 cm/s, and ICA-to-common carotid artery ratio ≥7.5. Compared with other published criteria, these thresholds are relatively high, 19 and therefore, a significant portion of our patients enter surveillance. The purpose of this study is to report the natural history of patients with asymptomatic carotid disease who were managed using these conservative CDUS criteria.…”

“…13–17 The widely referenced Society for Radiologists in Ultrasound Consensus Statement on CDUS criteria has indicated that an internal carotid artery (ICA) peak systolic velocity (PSV) of ≥230 cm/s be used as the criterion to establish ≥70% stenosis. 18 However, as previously demonstrated by Arous et al, 19 substantial variation exists in institutional protocols for determining the degree of stenosis and, presumably, the threshold for intervention. This ambiguity has a potential effect not only on patient outcomes but almost certainly also on health care costs.…”

Recomendação para a Quantificação pelo Ultrassom da Doença Aterosclerótica das Artérias Carótidas e Vertebrais: Grupo de Trabalho do Departamento de Imagem Cardiovascular da Sociedade Brasileira de Cardiologia – DIC - SBC

“…Porém, até o momento, não existe uma recomendação universalmente aceita que englobe um conjunto de critérios, assim como não há consenso sobre o peso relativo de cada um deles 95 . Recentemente um estudo avaliou dez instituições americanas e mostrou que, entre elas, havia a utilização de diferentes critérios Doppler ultrassonográficos para graduação das estenoses carotídeas gerando diferenças significativas no número de intervenções, subsequentemente impactando em custo no sistema de saúde 96 .…”