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Background: Confounding by indication is a serious threat to comparative studies using real world data. We assessed the utility of automated data-adaptive analytic approach for confounding adjustment when both claims and clinical registry data are available., Methods: We used a comparative study example of carotid artery stenting (CAS) vs. carotid endarterectomy (CEA) in 2005-2008 when CAS was only indicated for patients with high surgical risk. We included Medicare beneficiaries linked to the Society for Vascular Surgery's Vascular Registry >65 years old undergoing CAS/CEA. We compared hazard ratios (HRs) for death while adjusting for confounding by combining various 1) Propensity score (PS) modeling strategies (investigator-specified [IS-PS] vs. automated data-adaptive [ada-PS]); 2) data sources (claims-only, registry-only and claims-plus-registry); and 3) PS adjustment approaches (matching vs. quintiles-adjustment with/without trimming). An HR of 1.0 was used as a benchmark effect estimate based on CREST trial., Results: The cohort included 1,999 CAS and 3,255 CEA patients (mean age 76). CAS patients were more likely symptomatic and at high surgical risk, and experienced higher mortality (crude HR = 1.82 for CAS vs. CEA). HRs from PS-quintile adjustment without trimming were 1.48 and 1.52 for claims-only IS-PS and ada-PS, 1.51 and 1.42 for registry-only IS-PS and ada-PS, and 1.34 and 1.23 for claims-plus-registry IS-PS and ada-PS, respectively. Estimates from other PS adjustment approaches showed similar patterns., Conclusions: In a comparative effectiveness study of CAS vs. CEA with strong confounding by indication, ada-PS performed better than IS-PS in general, but both claims and registry data were needed to adequately control for bias., Competing Interests: HK and HM are affiliated with the department of Healthcare Quality Assessment, University of Tokyo, which is a social collaboration department supported by the National Clinical Database, Johnson & Johnson KK, and Nipro Corporation. HK has received lecture fees from Chugai Pharmaceutical Co., Ltd., Johnson & Johnson KK, and consultancy fees from Mitsubishi Tanabe Pharm and EP Croit Co., Ltd. JJJ is a full-time employee of Regeneron Pharmaceuticals. This study was conducted prior to her employment at the company. SS has served as a member of the US FDA advisory committee and as a consultant for Pfizer Inc., Medtronic, and Merck. SS has also received research funding from the National Institutes of Health, the Cystic Fibrosis Foundation, Pfizer Inc., and Bristol-Myers Squibb. All other authors have no conflicts to declare. The above do not alter our adherence to Plos One policies on sharing data and materials.

Importance: Although many factors influence the management of carotid artery stenosis, it is not well understood whether a preference toward procedural management exists when procedural volume and physician compensation are linked in the fee-for-service environment., Objective: To explore evidence for provider-induced demand in the management of carotid artery stenosis., Design, Setting, and Participants: The Department of Defense Military Health System Data Repository was queried for individuals diagnosed with carotid artery stenosis between October 1, 2006, and September 30, 2010. A hierarchical multivariable model evaluated the association of the treatment system (fee-for-service physicians in the private sector vs salary-based military physicians) with the odds of procedural intervention (carotid endarterectomy or carotid artery stenting) compared with medical management. Subanalysis was performed by symptom status at the time of presentation. The association of treatment system and of management strategy with clinical outcomes, including stroke and death, was also evaluated. Data analysis was conducted from August 15, 2015, to August 2, 2016., Main Outcomes and Measures: The odds of procedural intervention based on treatment system was the primary outcome used to indicate the presence and effect of provider-induced demand., Results: Of 10 579 individuals with a diagnosis of carotid artery stenosis (4615 women and 5964 men; mean [SD] age, 65.6 [11.4] years), 1307 (12.4%) underwent at least 1 procedure. After adjusting for demographic and clinical factors, the odds of undergoing procedural management were significantly higher for patients in the fee-for-service system compared with those in the salary-based setting (odds ratio, 1.629; 95% CI, 1.285-2.063; P < .001). This finding remained true when patients were stratified by symptom status at presentation (symptomatic: odds ratio, 2.074; 95% CI, 1.302-3.303; P = .002; and asymptomatic: odds ratio, 1.534; 95% CI, 1.186-1.984; P = .001)., Conclusions and Relevance: Individuals treated in a fee-for-service system were significantly more likely to undergo procedural management for carotid stenosis compared with those in the salary-based setting. These findings remained consistent for individuals with and without symptomatic disease.

Background: Effectiveness of carotid artery stenting (CAS) relative to carotid endarterectomy (CEA) among Medicare patients has not been established. We compared effectiveness of CAS versus CEA among Medicare beneficiaries., Methods and Results: We linked Medicare data (2000-2009) to the Society for Vascular Surgery's Vascular Registry (2005-2008) and the National Cardiovascular Data Registry's (NCDR) Carotid Artery Revascularization and Endarterectomy Registry (2006-2008/2009). Medicare patients were followed up from procedure date until death, stroke/transient ischemic attack, periprocedural myocardial infarction, or a composite end point for these outcomes. We derived high-dimensional propensity scores using registry and Medicare data to control for patient factors and adjusted for provider factors in a Cox regression model comparing CAS with CEA. Among 5254 Society for Vascular Surgery's Vascular Registry (1999 CAS; 3255 CEA) and 4055 Carotid Artery Revascularization and Endarterectomy Registry (2824 CAS; 1231 CEA) Medicare patients, CAS patients had a higher comorbidity burden and were more likely to be at high surgical risk (Society for Vascular Surgery's Vascular Registry: 96.7% versus 44.5%; Carotid Artery Revascularization and Endarterectomy Registry: 71.3% versus 44.7%). Unadjusted outcome risks were higher for CAS. Mortality risks remained elevated for CAS after adjusting for patient-level factors (hazard ratio, 1.24; 95% confidence interval, 1.06-1.46). After further adjustment for provider factors, differences between CAS and CEA were attenuated or no longer present (hazard ratio for mortality, 1.13; 95% confidence interval, 0.94-1.37). Performance was comparable across subgroups defined by sex and degree of carotid stenosis, but there was a nonsignificant trend suggesting a higher risk of adverse outcomes in older (>80) and symptomatic patients undergoing CAS., Conclusions: Outcomes after CAS and CEA among Medicare beneficiaries were comparable after adjusting for both patient- and provider-level factors., (© 2016 American Heart Association, Inc.)

Background and Purpose: After the 2005 National Coverage Determination to reimburse carotid artery stenting (CAS) for Medicare beneficiaries, the number of CAS procedures increased and carotid endarterectomy (CEA) decreased. We evaluated trends in surgeons' past-year CEA case-volume and 30-day mortality after CEA, and their association before and after the National Coverage Determination., Methods: In a retrospective cohort study of patients undergoing CEA (2001-2008) and CAS (2005-2008) using Medicare data, we described yearly trends of CEA and CAS rates, patient characteristics, and 30-day mortality after CEA. We used logistic regression adjusting for patient- and surgeon-level factors to assess the effect of surgeon case volume on 30-day mortality after CEA., Results: We identified 454 717 CEA and 27 943 CAS patients. Patients undergoing CEA in recent years were older and had more comorbidities than earlier years. CEA rates per 10 000 beneficiaries declined from 18.1 in 2002 to 12.7 in 2008, whereas median surgeon past-year case-volume declined from 27 to 21. The CAS rates peaked at 2.3 per 10 000 beneficiaries in 2006 but declined to 1.8 in 2008, resulting in declining overall revascularization procedure rates during 2005 to 2008. Thirty day post-CEA mortality was 1.40% (95% confidence interval, 1.34-1.47) in 2001 to 2002 and 1.17% (1.10-1.24) in 2007 to 2008. Surgeon's past-year case-volume of <10 was associated with higher 30-day mortality consistently during 2001 to 2008., Conclusions: The rate of CEA procedures decreased substantially during 2001 to 2008, as did surgeon past-year case-volume. The postprocedural mortality in Medicare beneficiaries was high compared with trial patients but somewhat improved over time. Those operated by lower past-year case-volume surgeons had increased mortality., (© 2015 American Heart Association, Inc.)

Objective: In the United States, vascular surgeons frequently perform carotid endarterectomy (CEA). Given the resource burden of unplanned readmission (URA), we sought to identify the predictors and consequences of URA after this common vascular surgery procedure to identify potential points of intervention., Methods: Using a prospective single-institution database, we retrospectively identified consecutive patients undergoing CEA (2001-2011). Demographic and perioperative factors were prospectively collected. The primary end point was 30-day postdischarge URA after CEA. The secondary end point was 1-year survival. We performed a univariable analysis for URA followed by a multivariable Cox model. A Kaplan-Meier analysis was performed for 1-year survival., Results: During the study period, 840 patients underwent 897 CEAs. The 30-day postdischarge overall readmission rate and URA rate were 8.6% and 6.5%, respectively. Most URA patients (n = 42; 73.4%) were readmitted for a CEA-related reason (headache, cardiac, hypertension, surgical site infection, bleeding/hematoma, stroke/transient ischemic attack, dysphagia, or hyperperfusion syndrome). Seventeen patients (29.3%) had more than one reason for URA. Median time to URA was 4 days (interquartile range, 1-9 days). Postoperative length of stay, indication for CEA, and discharge destination were not associated with URA. In multivariable analysis, in-hospital occurrence of congestive heart failure (hazard ratio [HR], 15.1; 95% confidence interval [CI], 4.7-48.8; P < .001), stroke (HR, 5.0; 95% CI, 1.8-14.0; P < .001), bleeding/hematoma (HR, 3.1; 95% CI, 1.4-6.9; P = .003), and prior coronary artery bypass grafting (HR, 2.0; 95% CI, 1.2-3.5; P = .01) were significantly associated with URA. Patients in the URA group also had decreased survival during 1 year (91% vs 96%; P = .01, log-rank)., Conclusions: The 30-day URA rate after CEA is low (6.5%). Prior coronary artery bypass grafting and in-hospital postoperative occurrence of stroke, bleeding/hematoma, and congestive heart failure identify those at increased risk of URA, and URA signals increased long-term risk of postoperative mortality., (Copyright © 2014 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.)

Introduction: Hospital length of stay (LOS) contributes to costs. Carotid endarterectomy (CEA) is performed frequently by vascular surgeons, making contemporary CEA LOS rates and predictors vital knowledge for quality evaluation and cost containment initiatives., Methods: Using a prospective single-institution database, we retrospectively identified consecutive patients undergoing CEA from 2001 to 2011. Demographic and perioperative factors were prospectively collected. The primary end point was extended postoperative LOS (ELOS), defined as postoperative LOS ≥2 days. Factors associated with ELOS were analyzed in a multivariable logistic regression model. Rates of 1-year readmission and death were compared with the Kaplan-Meier method (log-rank test)., Results: Eight hundred forty patients underwent 897 CEAs with 39% of procedures among females and 35% for symptomatic disease. One hundred two (11.4%) patients were inpatients prior to the day of CEA ("preadmitted"); their preoperative days by definition are not included in ELOS. Median postoperative LOS was 1 day (interquartile range, 1-2). Four hundred fourteen patients (46.2%) had ELOS. Preadmission was associated with ELOS (72% vs 41%; P < .01) and ELOS patients were less likely to be discharged home (11.9% vs 1.5%; P < .01). There was no association between ELOS and unplanned 30-day postdischarge readmission (6.0% vs 7.0%; P = .59). On multivariable analysis, preoperative factors significantly associated with ELOS included preadmission (adjusted odds ratio [OR], 3.3; 95% confidence interval [CI], 1.9-5.7; P < .001), history of congestive heart failure (OR, 2.1; 95% CI, 1.1-4.2; P = .03), female gender (OR, 1.9; 95% CI, 1.4-2.6; P < .001), and history of chronic obstructive pulmonary disease (OR, 1.7; 95% CI, 1.0-2.9; P = .04). Operative factors included electroencephalography change (OR, 1.9; 95% CI, 1.2-3.2; P = .01), operating room start time after 12:00 pm (OR, 1.7; 95% CI, 1.2-2.4; P < .01), and total operating room time (OR, 1.5 per hour; 95% CI, 1.2-2.9; P < .01). Postoperative factors included transfer to intensive care unit (OR, 5.4; 95% CI, 3.1-9.4; P < .01), number of in-hospital postoperative complications (OR, 3.7; 95% CI, 2.2-6.5; P < .01), and Foley catheter placement (OR, 2.1; 95% CI, 1.3-3.4; P < .01). Over 1 year, ELOS was associated with increased hospital readmission (93.6% vs 84.7%; log-rank test, P < .01) and decreased survival (95.1% vs 98.3%; log-rank test, P < .01)., Conclusions: Nearly half of CEA patients were discharged on or after postoperative day 2. Interventions on modifiable risk factors, such as early Foley catheter placement to prevent urinary retention and morning CEA scheduling, may decrease LOS. ELOS may identify a subset of patients at increased risk for long-term readmission and mortality., (Copyright © 2014 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.)

Objective: Multiple studies have established that patch angioplasty following carotid endarterectomy (CEA) reduces the risk of subsequent stroke and restenosis compared with primary closure. Previous reports have also demonstrated bovine pericardium to be associated with similar rates of postoperative complications and restenosis compared with other patch materials. Due to favorable handling and sonographic properties, bovine pericardium has become increasingly popular as a patch option in recent years. However, the intermediate- and long-term performance of this material remains incompletely defined. Through a retrospective analysis of our carotid endarterectomy experience, we sought to compare the bleeding, infection, and pseudoaneurysm rates with bovine pericardium patch closure to those with Dacron patch and primary closure. In this study, 1331 primary carotid endarterectomies performed in our institution between 1996 and 2008 were grouped according to the method of arteriotomy closure: primary closure (PC) (216, 16.3%), Dacron patch angioplasty (DPA) (642, 48.2%), and bovine pericardial patch angioplasty (BPA) (457, 34.3%). Demographic variable and postoperative outcome measures collected real-time via a designated database manager were assessed by univariate and multivariate analysis., Results: Mean follow-up for the entire cohort was 46.1 months. There were no statistically significant differences in rates of postoperative wound infection, hematoma, pseudoaneurysm formation, or 30-day stroke or 30-day mortality among the three groups. Combined 30-day stroke and death was significantly lower in the PC cohort (0.5% vs 2.3% DPA vs 2.4% BPA; P = .94, BPA vs DPA; P = .001, BPA vs PC; P = .001, DPA vs PC), while 5-year restenosis after both DPA (2.0% ± 0.6%) and BPA (1.1% ± 0.6%) was significantly lower compared with PC (5.2% ± 1.6%) (P = .03, DPA vs PC; P = .008, BPA vs PC; P = .14, BPA vs DPA). Five-year survival following BPA (77.9% ± 3.6%) was significantly improved compared with PC (66.9% ± 3.5%) and DPA (60.8% ± 2.1%) in univariate analysis (P = .24, DPA vs PC; P = .01, BPA vs PC; P = .03, BPA vs DPA), with statin use (P = .004) and male gender (P = .05) being positive predictors of enhanced survival on multivariate analysis., Conclusions: This single-institution, retrospective review represents the largest reported experience with BPA after CEA to date and is the only report comparing outcomes after BPA to PC or to DPA. Our experience further demonstrates that patch angioplasty is protective against restenosis after CEA compared with PC. Equivalent rates of perioperative bleeding, infection, and pseudoaneurysm formation were seen with each closure strategy in this study., (Copyright © 2012 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.)

Objectives: Carotid artery stenting (CAS) is an alternative to carotid endarterectomy (CEA) for treating carotid artery stenosis. We conducted a systematic review and meta-analysis of the clinical trials to date comparing these two procedures to determine their relative safety and efficacy., Methods: Searches of the Cochrane Controlled Trials Register, MEDLINE, and EMBASE identified two cohort studies and eight randomized, controlled trials (RCTs) comparing CEA and CAS. Meta-analysis was performed for the primary outcome of 30-day stroke or death, using an intention-to-treat analysis. Between-trial heterogeneity was assessed using the chi2 test, and fixed-effects models were used to pool estimates in the absence of heterogeneity. Meta-regression was conducted to investigate potential effect differences by patient, intervention, and trial characteristics. To evaluate the effect of study design and inclusion criteria, sensitivity and subgroup analyses were performed., Results: Ten trials encompassing 3580 patients were analyzed. Patients who underwent CAS had a higher risk of 30-day stroke/death relative to patients who underwent CEA (risk ratio [RR], 1.30; 95% CI, 1.01-1.67). Meta-analysis and meta-regression demonstrated no between-trial heterogeneity. Sensitivity analysis of only RCTs showed similar higher risk for stroke/death (RR, 1.38; 95% CI, 1.06-1.79) in CAS patients. Subgroup analysis of trials enrolling only symptomatic patients showed higher risk of 30-day stroke/death (RR, 1.63; 95% CI, 1.18-2.25), but trials enrolling both symptomatic and asymptomatic patients showed no significant differences (RR, 0.89; 95% CI, 0.59-1.35)., Conclusions: Meta-analysis of trials to date shows CAS is associated with higher 30-day risk of stroke/death compared with CEA. Thus, for the patient at average surgical risk, the role of CAS is unproven, especially for symptomatic patients. And for the patient at high surgical risk, the role of any intervention is uncertain in the setting of competing comorbidities. The results of ongoing clinical trials in this area will likely provide additional evidence to support treatment choices for carotid artery stenosis.

The restenosis rates of 5% to 15% have been reported after carotid endarterectomy (CEA). We undertook this investigation to determine whether the routine practice of carotid artery patch closure and intraoperative completion duplex ultrasonography would result in lower rates of carotid restenosis after CEA. All consecutive carotid endarterectomies performed between 2000 and 2004 at a single institution were reviewed retrospectively. Patients underwent CEA using a longitudinal arteriotomy, followed by routine patching and intraoperative completion duplex ultrasonography. Only patients with at least one postoperative duplex scan performed at a minimum of 180 days after CEA were included. During the 5-year study period, 407 consecutive carotid endarterectomies were performed, with a combined 30-day stroke and mortality rate of 2.5%; 217 patients (53%) had one or more duplex ultrasound examinations performed at least 180 days after CEA. The mean follow-up duration was 692 days. Of the patients who underwent intraoperative intervention based on the results of the completion duplex study, none experienced restenosis, stroke, or death. CEA that is performed with routine patching and intraoperative duplex completion ultrasonography is a safe, durable operation with restenosis rates below those commonly reported.

The role of carotid endarterectomy in the prevention of stroke was validated by two randomized clinical trials, the North American Symptomatic Carotid Endarterectomy (NASCET) and the Asymptomatic Carotid Atherosclerosis Study (ACAS). However, these trials excluded patients at high risk for perioperative stroke and other morbidity, raising concerns for the applicability of the trial results to the general population. Some have also suggested these "high-risk" patients are better suited for carotid artery stenting with the belief that stenting has lower morbidity and mortality. In this article, we review many of the commonly accepted high-risk factors for carotid endarterectomy (CEA) and examine their outcomes. High-risk patients are more common than generally believed and their outcomes may be the same with carotid endarterectomy as it is with carotid stenting. Truly "high-risk" patients with shortened life expectancy are best served with no intervention.