Clinical referral patterns for carotid artery stenting versus carotid endarterectomy: results from the Carotid Artery Revascularization and Endarterectomy Registry.

BACKGROUND Carotid artery stenting (CAS) and carotid endarterectomy (CEA) are alternative strategies for stroke prevention in patients with atherosclerotic carotid disease. Although randomized clinical trials are the gold standard for assessing the relative benefits of different treatments, observational research is necessary for determining "real-world" effectiveness. Current recommendations limit the application of CAS to high-risk patients, undermining the ability to "balance" the characteristics of patients treated with either approach. We compared the clinical profiles of patients referred for CAS versus CEA in a large national database. METHODS AND RESULTS Clinical characteristics of 12 701 patients referred for CAS or CEA in the National Cardiovascular Data Registry-Carotid Artery Revascularization and Endarterectomy were compared for 44 clinical and demographic variables. To investigate the comparability of CAS and CEA patients, we stratified the cohort into quintiles of the propensity score for referral for CAS. Among 8069 patients referred for CAS and 4632 referred for CEA, the CAS patients had significantly more comorbidities. Whereas the propensity model balanced most covariates, the pooled standardized differences (≥10%) suggested persistent imbalance for ischemic heart disease, recent myocardial infarction, and restenosis of prior CAS/CEA, all of which were more common in the CAS group. After stratification of propensity scores by quintile, CEA patients comprised only 14% of the upper 2 quintiles. CONCLUSIONS Characteristics of patients referred for CAS differ markedly from those referred for CEA. Because of extreme clinical disparities between these patients, generalizable comparative effectiveness analyses of observational data will be difficult.