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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: Clinical trials demonstrated the efficacy of carotid artery stenting (CAS) relative to carotid endarterectomy when performed by physicians with demonstrated proficiency. It is unclear how CAS performance may be influenced by the diversity in CAS and non-CAS provider volumes in routine clinical practice., Methods and Results: We linked Medicare claims to the Centers for Medicare and Medicaid Services' CAS Database (2005-2009). We assessed the association between 30-day mortality and past-year physician (0, 1-4, 5-9, 10-19, ≥20) and hospital (<10, 10-19, 20-39, ≥40) CAS volumes and past-year hospital coronary and peripheral stenting volumes (<200, 200-399, 400-849, ≥850) among beneficiaries at least 66 years of age. Unadjusted 30-day mortality risk was 1.8% (95% confidence interval [CI], 1.6-2.0) for 19 724 patients undergoing CAS by 2045 physicians in 729 hospitals. Median past-year CAS volume was 9 (interquartile range, 4-19) for physicians and 23 (interquartile range, 12-41) for hospitals. Compared to physicians performing ≥20 CAS in the past year, lower CAS volumes were associated with higher adjusted risks of 30-day morality (P value for trend < 0.05): 1.4 (95% CI, 0.9-2.3) for 0 past-year CAS, 1.3 (95% CI, 0.9-1.8) for 1 to 4, 1.1 (95% CI, 0.8-1.6) for 5 to 9, and 0.9 (95% CI, 0.7-1.4) for 10 to 19. An inverse relationship between 30-day mortality and past-year CAS hospital volume as well as past-year hospital non-CAS volume, past-year hospital non-CAS volume, and 30-day mortality was also noted., Conclusions: Among Medicare patients, an inverse relationship exists between physician and hospital CAS volumes and hospital non-CAS stenting volume and 30-day mortality, even after adjusting for all pertinent patient- and hospital-level factors., (© 2015 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.)

Importance: Despite increased carotid artery stenting (CAS) dissemination following the 2005 National Coverage Determination, to our knowledge, periprocedural and long-term outcomes have not been described among Medicare beneficiaries., Objective: To describe the incidence of outcomes during and after the periprocedural period among Medicare beneficiaries undergoing CAS., Design, Setting, and Participants: Observational study with a mean follow-up time of approximately 2 years among 22,516 fee-for-service Medicare beneficiaries at least 66 years old undergoing CAS (2005-2009) who were linked to the Centers for Medicare & Medicaid Services' CAS database. Database procedure dates were required to fall during a Medicare hospitalization for CAS., Main Outcomes and Measures: Periprocedural (30-day) and long-term risks of mortality and stroke or transient ischemic attack, as well as periprocedural myocardial infarction. Subgroups were based on sociodemographic, clinical, and center-level factors, as well as the Stenting and Angioplasty With Protection in Patients at High Risk for Endarterectomy (SAPPHIRE) trial or Carotid Revascularization Endarterectomy vs Stenting Trial (CREST) enrollment criteria., Results: The mean patient age was 76.3 years, 60.5% were male, 93.8% were of white race, 91.2% were at high surgical risk, 47.4% were symptomatic, and 97.4% had carotid stenosis of at least 70%. Crude 30-day mortality, stroke or transient ischemic attack, and myocardial infarction risks were 1.7% (95% CI, 1.5%-1.8%), 3.3% (95% CI, 3.0%-3.5%), and 2.5% (95% CI, 2.3%-2.7%), respectively. Mortality during a mean follow-up time of 2 years was 32.0% (95% CI, 31.0%-33.0%), with rates of 37.3% (95% CI, 35.8%-38.7%) among symptomatic patients and 27.7% (95% CI, 26.4%-28.9%) among asymptomatic patients. Older age, symptomatic carotid stenosis, and nonelective hospital admission were associated with increased adjusted hazards of mortality and stroke or transient ischemic attack during and after the periprocedural period. The presence of a stroke center, government ownership, and a hospital bed capacity of 500 or more were associated with increased adjusted hazards of periprocedural mortality and stroke or transient ischemic attack. Few patients met the SAPPHIRE trial or CREST enrollment criteria primarily because physicians did not meet proficiency requirements either due to exceeding periprocedural complication trial thresholds or not meeting minimum CAS volume requirements., Conclusions and Relevance: Competing risks may limit the benefits of CAS in certain Medicare beneficiaries, particularly among older and symptomatic patients who have higher periprocedural and long-term mortality risks. The generalizability of trials like the SAPPHIRE or CREST to the Medicare population may be limited, underscoring the need to evaluate real-world effectiveness of carotid stenosis treatments.

Objective: Open surgical reconstruction for supra-aortic trunk occlusive disease persists despite advances in endovascular therapy. Although extrathoracic reconstructions developed as a safer alternative to transthoracic reconstructions, contemporary national data evaluating relative rates of operative outcomes are lacking., Methods: With use of the National Surgical Quality Improvement Program (2005-2011), patients who underwent transthoracic or extrathoracic reconstruction were evaluated. Patients with nonocclusive indications were excluded. The primary outcome was a composite end point of stroke/myocardial infarction (MI)/death. Secondary outcomes were 30-day postoperative complications. Univariate and multivariable regression analyses were performed., Results: Overall, 83 patients (10.7%) underwent transthoracic reconstructions and 692 patients (89.3%) underwent extrathoracic reconstructions. Vascular surgeons performed most transthoracic (96%) and extrathoracic (97%) reconstructions. The most common extrathoracic reconstructions were carotid-subclavian bypass (68%), carotid-carotid bypass (14%), and subclavian transposition (7%). Less commonly, axillary-axillary bypass (6%), subclavian-axillary bypass (2%), subclavian-subclavian bypass (1%), and carotid transposition (1%) were performed. At the time of operation, 10% (transthoracic reconstructions) and 8% (extrathoracic reconstructions) of patients had a concurrent carotid endarterectomy (P < .60). Analysis of more than 20 characteristics showed that the groups did not differ significantly. The two groups had similar rates of postoperative stroke (1.2% in the transthoracic reconstruction group vs 2.2% in the extrathoracic reconstruction group; P > .99), MI (0% vs 1.3%; P = .61), death (2.4% vs 1.3%; P = .33), and stroke/MI/death (3.6% vs 3.8%; P > .99). Transthoracic reconstruction patients had longer hospital stays (6.3 days vs 4.0 days; P < .0002), received more transfusions (8.4% vs 2.5%; P < .0096), and had higher rates of postoperative sepsis (3.6% vs 0.3%; P < .01) and venous thromboembolic complications (3.6% vs 0.4%; P < .02). After adjustment for other factors, including surgical approach, stroke/MI/death was significantly associated with postoperative pneumonia (odds ratio [OR], 26.0; 95% confidence interval [CI], 6.29-108.28; P < .0001), postoperative ventilator dependence (OR, 12.45; 95% CI, 2.74-56.48; P = .001), and postoperative return to the operating room (OR, 4.75; 95% CI, 1.67-13.54; P = .004)., Conclusions: At U.S. hospitals, extrathoracic reconstruction is the more common reconstruction for supra-aortic trunk occlusive disease. Both approaches carry acceptably low rates of death, MI, and stroke. Transthoracic reconstruction results in more resource utilization because of its postoperative complications and greater complexity., (Copyright © 2014 Society for Vascular Surgery. 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.

Objectives The aim of this study was to examine variation in outcomes for patients receiving carotid artery stenting (CAS) across a sample of U.S. hospitals and assess the extent to which this variation was attributable to differences in case mix and procedural volume. Background As CAS is increasingly being used throughout the United States, assessing hospital variation in CAS outcomes is critical to understanding and improving the quality of care for patients with carotid artery disease. Methods Hospitals participating in the National Cardiovascular Data Registry–Carotid Artery Endarterectomy and Revascularization Registry contributing more than 5 CAS procedures from 2005 through 2013 were eligible for inclusion. We estimated unadjusted and risk-standardized rates of in-hospital stroke or death for each participating hospital using a previously validated prediction model and applying hospital-level random effects. Results There were 188 hospitals contributing 19,381 CAS procedures during the period of interest. Unadjusted and risk-standardized in-hospital stroke or death rates ranged from 0% to 18.8% and 1.2% to 4.7%, respectively. Operator and hospital volumes were not significant predictors of outcomes after adjustment for case mix (p = 0.15 and p = 0.09, respectively). Conclusions CAS outcomes vary 4-fold among hospitals, even after adjustment for differences in case mix. Future work is needed to identify the sources of this variation and develop initiatives to improve patient outcomes. [ABSTRACT FROM AUTHOR]