A Comparison of Outcomes Associated With Carotid Artery Stent Placement Performed Within and Outside Clinical Trials in the United States

Study Questions:

What are the differences in the clinical characteristics and outcome of patients undergoing carotid artery stenting (CAS) within clinical trials, and those treated outside clinical trials, in a large national cohort?


The authors compared the outcome of CAS performed within and outside clinical trials and associated in-hospital outcomes using data from the Nationwide Inpatient Survey data files from 2005 to 2009.


A total of 81,638 patients underwent CAS over the 5-year time period, and of these, 19.6% (n = 16,078) underwent the procedure as part of a clinical trial. Patients treated in trials were younger, and more likely to be men. Patients treated outside of clinical trials had higher in-hospital mortality (1.12% vs. 0.53%; p = 0.0005) and a higher rate of composite endpoint of stroke, cardiac events, and death (4.91% vs. 3.85%; p = 0.02). After adjusting for age, gender, presence of renal failure, and hospital bed size, CAS performed as part of a clinical trial was associated with lower rates of in-hospital mortality (odds ratio [OR], 0.467; 95% confidence interval [CI], 0.290-0.751; p = 0.0017) and composite endpoint of stroke, cardiac events, and death (OR, 0.752; 95% CI, 0.594-0.952; p = 0.0180).


Patients undergoing CAS as part of clinical trials have a better outcome compared with patients undergoing CAS in routine clinical practice.


The results of this study mirror the work of Yeh and colleagues (Circulation 2011;123:1384-90), and demonstrate that patients who are treated as part of postmarketing studies or clinical trials have better outcomes than patients who are treated in routine clinical practice. One factor that may explain this difference is the symptomatic status of the patient prior to the procedure. Currently, Medicare will only reimburse for CAS in asymptomatic patients who are enrolled in clinical trials, whereas high-risk symptomatic patients can be stented outside such trials. It is not clear that these differences can be adjusted for using administrative data. Nevertheless, these data highlight the need for ongoing monitoring of outcome for all patients undergoing carotid revascularization (both CAS and carotid endarterectomy).

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Vascular Medicine, Interventions and Vascular Medicine

Keywords: Stroke, Hospital Mortality, Hospital Bed Capacity, Endarterectomy, Carotid, Carotid Arteries, Angioplasty, Balloon, Coronary, Stents, Renal Insufficiency, Carotid Artery, Common, Cardiology, Confidence Intervals, Medicare, Carotid Stenosis, United States

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