Contemporary Trends in Physician Utilization Rates of CEA and CAS for Asymptomatic Carotid Stenosis among Medicare Beneficiaries

Background: Carotid revascularization for asymptomatic carotid artery stenosis (ACAS) has become increasingly controversial in the past few decades as the best medical therapy has improved. The aim of this study was to assess and define contemporary trends in the rate of carotid revascularization procedures for ACAS in the United States and to characterize outlier physicians performing a higher rate of asymptomatic revascularization compared to their peers. Methods: We used 100% Medicare fee-for-service claims to identify all patients who were newly diagnosed with ACAS between 01/2011–06/2018. Patients with symptomatic carotid artery stenosis, those with prior carotid revascularization, and surgeons who performed ≤10 CEAs during the study period were excluded. We used a hierarchical multivariable logistic regression model to evaluate patient and physician characteristics associated with undergoing a carotid endarterectomy or carotid artery stent procedure within 3 months after the initial diagnosis of ACAS. We also assessed temporal trends in carotid revascularization rates over time using the Cochran-Armitage Trend Test. Results: Overall, 795,512 patients (median age 73.9 years, 50.9% male, 87.6% white) had a first-time diagnosis of ACAS during the study period, of which 23,481 (3.0%) underwent carotid revascularization within 3 months. There was a significant decline in overall carotid artery revascularization rates over time (2011: 3.2% vs. 2018: 2.1%; P < 0.001). The median and mean physician-specific carotid revascularization rates were 2.0% (IQR 0.0%–6.3%) and 4.7% ± 7.1%, respectively. Three-hundred and fifty physicians (5.2%) had carotid revascularization rates ≥19%, which was more than 2 standard deviations above the mean. After adjusting for patient-level characteristics, physician-level variables associated with carotid revascularization for newly diagnosed ACAS included male sex (adjusted OR 1.59, 95% CI 1.35–1.89), more years in practice (≥31 vs. <10 years, aOR 1.64, 95% CI 1.32–2.04), rural practice location (aOR 1.34, 95% CI 1.18–1.52), Southern region practice location (versus Northeast, aOR 1.54, 95% CI 1.39–1.69), and lower volume of ACAS patients (lower versus upper tertile, aOR 2.62, 95% CI 2.39–2.89). Cardiothoracic surgeons had a 1.52-fold higher odds of carotid revascularization compared to vascular surgeons (95% CI 1.36–1.68), whereas cardiologists and radiologists had lower intervention rates (both, P < 0.05). Conclusions: The current early revascularization rate for newly diagnosed ACAS is <5% among proceduralists in the United States, and has been decreasing steadily since 2014. There are particular physician-level characteristics that are associated with higher rates of carotid revascularization that cannot be fully contextualized without high-level contemporary outcomes data to guide decision making in ACAS.