Benenati, James F.

Introduction: The relative performance of carotid artery stenting (CAS) and carotid endarterectomy (CEA) among Medicare beneficiaries in routine clinical practice has not been established. Objective: To compare the performance of CAS relative to CEA among Medicare beneficiaries. Methods: We linked Medicare data (2000-2009) to the Society for Vascular Surgery’s Vascular Registry (SVS-VR; 2005-2008) and to the NCDR® Carotid Artery Revascularization and Endarterectomy Registry (CARE; 2006-2008/9). Medicare patients aged ≥66 years undergoing CAS or CEA were followed from the procedure date for the outcomes of death, stroke/transient ischemic attack (TIA), peri-procedural myocardial infarction (MI) or a composite endpoint for these outcomes. We derived high-dimensional propensity scores using registry and Medicare data to control for patient-level factors and adjusted for provider-level factors including past-year CAS/CEA physician and hospital volume, hospital ownership, teaching affiliation, and hospital size in a Cox regression model comparing CAS to CEA. Results: Among 5,254 SVS-VR (1,999 CAS and 3,255 CEA) and 4,055 CARE (2,824 CAS and 1,231 CEA) patients, CAS patients were more often at higher surgical risk (SVS-VR: 96.7% vs. 44.5%; CARE: 71.3% vs. 44.7%) and had a higher comorbidity burden. Crude outcome risks for death and stroke/TIA were lower for CEA. Adjusting for patient-level factors drove estimates downwards for CAS relative to CEA but only after further adjustment for provider-level factors did the performance of CAS and CEA become comparable on all outcomes (figure 1). Conclusion: Performance of CAS and CEA among Medicare beneficiaries was comparable after accounting for patient- and provider-level factors, which is consistent with landmark trials. Further studies are needed to understand the role of heterogeneity in provider-level characteristics.

Diagnostic criteria to classify severity of internal carotid artery (ICA) stenosis vary across vascular laboratories. Consensus-based criteria, proposed by the Society of Radiologists in Ultrasound in 2003 (SRUCC), have been broadly implemented but have not been adequately validated. We conducted a multicentered, retrospective correlative imaging study of duplex ultrasound versus catheter angiography for evaluation of severity of ICA stenosis. Velocity data were abstracted from bilateral duplex studies performed between 1/1/2009 and 12/31/2015 and studies were interpreted using SRUCC. Percentage ICA stenosis was determined using North American Symptomatic Carotid Endarterectomy Trial (NASCET) methodology. Receiver operating characteristic analysis evaluated the performance of SRUCC parameters compared with angiography. Of 448 ICA sides (from 224 patients), 299 ICA sides (from 167 patients) were included. Agreement between duplex ultrasound and angiography was moderate (κ = 0.42), with overestimation of degree of stenosis for both moderate (50–69%) and severe (⩾ 70%) ICA lesions. The primary SRUCC parameter for ⩾ 50% ICA stenosis of peak-systolic velocity (PSV) of ⩾ 125 cm/sec did not meet prespecified thresholds for adequate sensitivity, specificity, and accuracy (sensitivity 97.8%, specificity 64.2%, accuracy 74.5%). Test performance was improved by raising the PSV threshold to ⩾ 180 cm/sec (sensitivity 93.3%, specificity 81.6%, accuracy 85.2%) or by adding the additional parameter of ICA/common carotid artery (CCA) PSV ratio ⩾ 2.0 (sensitivity 94.3%, specificity 84.3%, accuracy 87.4%). For ⩾ 70% ICA stenosis, analysis was limited by a low number of cases with angiographically severe disease. Interpretation of carotid duplex examinations using SRUCC resulted in significant overestimation of severity of ICA stenosis when compared with angiography; raising the PSV threshold for ⩾ 50% ICA stenosis to ⩾ 180 cm/sec as a single parameter or requiring the ICA/CCA PSV ratio ⩾ 2.0 in addition to PSV of ⩾ 125 cm/sec for laboratories using the SRUCC is recommended to improve the accuracy of carotid duplex examinations.