| | Modification of outcomes by lowering ischemic events after reconstruction of extracranial vessels (MOLIERE): An internet-based prospective study to evaluate and improve the effectiveness of carotid endarterectomyPresented at The Twenty-eighth Annual Meeting of the Canadian Society for Vascular Surgery, Calgary, Alberta, Canada, Sep 29-30, 2006. Received 4 September 2007; accepted 18 November 2007. BackgroundIndependent audits have been proposed to improve carotid endarterectomy (CEA) effectiveness. This study used the online registry Modification of Outcomes by Lowering Ischemic Events after Reconstruction of Extracranial Vessels (MOLIERE) to evaluate the effectiveness of CEA in the Province of Quebec. The concept of MOLIERE is that surgeon involvement in a prospective manner is a prerequisite for them to evaluate, compare, and improve their practice. MethodsAll Quebec surgeons who performed CEA were invited to participate in this study sponsored by the Société des sciences vasculaires du Québec, the Canadian Society for Vascular Surgery and the Association des chirurgiens vasculaires du Québec. Surgeons prospectively entered data for 60 variables relevant to CEA in an online, secure, and confidential database between May 24, 2004, and May 31, 2005. Patient inclusion had to occur before surgery. After the study was completed, charts of all CEAs performed in each participating center were reviewed to validate the results of MOLIERE. For each participating institution, results of CEA that were not entered in the registry were also reviewed. ResultsA total of 279 patients (mean age, 69 years; range, 46-91 years) undergoing a CEA were enrolled in MOLIERE by 23 surgeons from 10 institutions in Quebec; 157 (56%) were symptomatic, and 122 (44%) were asymptomatic. Carotid endarterectomies were performed with patch angioplasty in 252 (89%), primary closure in 24 (9%), and by eversion in six (2%). Follow-up at 30 days was achieved for all patients. The 30-day stroke or death rates for symptomatic and asymptomatic patients were 3.2% (5 of 157, 95% confidence interval [CI], 1.2%-7.4%) and 0%. Validation was excellent for patients who were entered in the registry, with no additional deaths or strokes than those reported by the surgeons. The validation process revealed that participating surgeons entered 66% (279 of 424) of their patients in the registry. Indications and stroke or death rates (SDRs) for those patients who were not entered in the registry were not statistically different (symptomatic, 54% [79 of 145]; SDR of 1.3% [1 of 76] for symptomatic and 1.5% [1 of 66] for asymptomatic). In participating institutions, 11 surgeons did not participate. The SDRs for patients operated on by nonparticipating surgeons were higher but not statistically different than rates for patients operated on by participating surgeons (3.7% [5 of 136] vs 1.7% [7 of 424], P = .16). There was a trend toward higher stroke rate for patients operated on by nonparticipating surgeons (3.7% [5 of 136] vs 1.2% [5 of 424], P = .056). Mean postoperative length of stay was statistically higher for patients operated on by nonparticipating surgeons (4.7 vs 3.4 days, P = .046). The SDRs were adequate for all surgeons in participating centers, with 95% CI within accepted standards for symptomatic and asymptomatic patients. ConclusionMOLIERE is the first Canadian online prospective registry allowing surgeons to audit CEA results. The SDRs for participating surgeons were valid and within standards. Scientific vascular societies played a key role in supporting this project. Such audits allow surgeons and medical stroke experts to examine the appropriateness and results of CEAs in their institutions to improve them. The future of MOLIERE is in validation of its concept, increased participation by surgeons, and integration of a multidisciplinary approach. Despite randomized controlled trials1, 2 showing stroke risk reduction by the addition of carotid endarterectomy (CEA) to the best medical treatment for a precise subset of patients and despite clinical guidelines that followed,3 concerns about the use and effectiveness of CEA remain. Kennedy et al4 recently published a retrospective study with administrative data and chart review to examine CEA appropriateness as performed in four Western Canadian provinces between January 2000 and December 2001. Only half (52.3%) of the CEAs met their criteria for appropriateness, and CEA for “inappropriate” reasons occurred at an overall rate of 10.3%. Tu et al,5 in a retrospective analysis of CEA complication rates in >6000 patients operated on in 34 hospitals in Ontario, reported a 4.7% rate of stroke or death in asymptomatic patients. On the basis of the results, the authors appropriately questioned whether these asymptomatic patients were receiving the benefit of CEA reported in the Asymptomatic Carotid Atherosclerosis Study (ACAS) trial, where the 30-day stroke and death rate (SDR) was 2.3%. As for any other prophylactic treatments, concerns about the appropriateness and risk of CEA and carotid stenting are more real than ever. How can we ensure that patients are offered CEAs at acceptable risk and for appropriate indications?6 The Modification of Outcomes by Lowering Ischemic Events after Reconstruction of Extracranial Vessels (MOLIERE) prospective observational study is designed to address several current controversies by allowing all surgeons in the province of Quebec to enroll their own patients undergoing CEA, in an innovative online database. The concept behind MOLIERE is that surgeon and neurologist involvement in a prospective manner is a prerequisite for them to evaluate, compare, and improve their practice. Therefore, the objectives of our study were to: 1.demonstrate the feasibility of an innovative, online, prospective registry, 2.evaluate the indications and results of CEAs in participating institutions, and 3.validate this auditing tool. Methods  Participating institutions We used the Med-Echo administrative database to identify 28 institutions where at least one CEA had been performed in Quebec. Surgeons of these institutions were invited to participate in MOLIERE, and the involvement of neurologists was suggested. A protocol reviewed by a research committee composed of members of the Quebec Vascular Society (Association des chirurgiens vasculaires du Québec) and La Société des sciences vasculaires du Québec (SSVQ) was sent to the surgeons. To participate in the study, the protocol had to be approved by the Research Ethics Board of the surgeons’ hospital. The protocol clearly stated that two independent reviewers would have access to the charts of all the CEA patients operated on that year in the participating institution. Surgeons had to obtain signed informed consent from each patient enrolled stating their agreement that their personal information concerning the CEA would be available on a secure Web-based database. The protocol also stated that all participating surgeons would receive their personal results in a confidential matter. This would subsequently promote positive criticism among the group of surgeons in each respective hospital. Participating surgeons, defined as surgeons who enrolled at least one patient in the database, were encouraged to include all their patients in the registry. Web-based database An Internet database available to surgeons 24 hours a day, 7 days a week was established with the help of Gestion recherche clinique Québec (GEREQ), a government-funded agency that promotes clinical research through online databases and provides investigators with an integrated electronic data management and E-learning platform. GEREQ’s systems and services are in compliance with international regulations and guidelines, including the International Conference on Harmonisation, the United States Food and Drug Administration, Health Canada, and the European Agency for the Evaluation of Medicinal Products. The database for MOLIERE contained 60 variables relevant to CEA, which were divided into four categories: •Identification and preoperative assessment addressed the issue of appropriateness, with variables such as CEA indication, risk factors for stroke, degree of stenosis, and preoperative investigations. Symptomatic patients were defined as those having ipsilateral hemispheric symptoms or amaurosis fugax ≤6 months. •The hospitalization section evaluated information about hospital stay and technical aspects of the procedure as well as the use of medications. •The postoperative assessment section included variables related to perioperative complications such as death, stroke, transient ischemic attack, cervical hematoma, cardiac complications, and reoperation. All new deficits lasting >24 hours were considered a stroke. No attempt was made to distinguish major or disabling strokes from minor events. Information about postoperative brain imaging, cranial nerve damage, and dysphagia was also requested. For ease of use, the variables were presented to surgeons as an online survey. To maintain restricted access to the database, each surgeon was assigned a unique login name and password selected by GEREQ. An information session was held at the 2004 Entretiens Vasculaires meeting by GEREQ to teach surgeons how to use the Web site. To ensure the prospective nature of our study and to limit bias, patient registration had to be completed before surgery. Demographic data and information pertaining to the surgery itself or hospitalization could be completed at the surgeons’ discretion at any time after patient registration, but data could not be confirmed in the databank before 30 days to ensure the registration of all 30-day complications during the follow-up period. Patient enrollment started on May 24, 2004 and ended on May 31, 2005, inclusively, with database closure on December 31, 2005. Validation We retrospectively identified all charts of patients treated by CEA during the study period in participating institutions. Patients operated on by participating as well as nonparticipating surgeons were reviewed. The proportions of patients not included in the study by participating surgeons and the number of patients operated on by nonparticipating surgeons in participating institutions were verified. Charts were reviewed by two independent research assistants blinded to the MOLIERE database. Validation included data about demographics and complications such as stroke, death, cardiac complications, readmission, and reintervention. The auditors had access to patient hospital files in July and August 2006, which was a year after the last patient was registered for the study. By this means, the auditors had access to the outpatient files and any external clinical visit to validate follow-up data at 30 days. For comparison, Med-Echo also provided the number of cases in each hospital during the study period. Statistical analyses Descriptive statistics were recorded. Continuous data are presented as means ± standard deviation, and dichotomous data, as percentages. The Student and Pearson χ2 tests were applied for univariate analysis, and logistic regression for multivariate analysis. The modified Wald method was used to calculate the 95% confidence intervals (CI) All values of P < .05 were considered statistically significant. Results Participation and feasibility Carotid endarterectomies were performed by 34 surgeons in the 10 participating centers, two academic centers, and eight community hospitals. The 23 surgeons who entered at least one CEA patient in MOLIERE database were defined as participating surgeons. The 11 surgeons working in those 10 centers who did not enter any patients were defined as nonparticipating surgeons. All but one of the surgeons who decided to participate were vascular surgeons. The remaining surgeons performing CEA in Quebec in 18 nonparticipating centers refused to participate in MOLIERE. Data from these centers were not available, but according to the Med-Echo administrative database, 636 CEAs were performed in these centers during MOLIERE, and six of the 18 centers had a volume of less than six CEAs. The reasons invoked by those 18 centers for not participating are reported in Table I.  | Reasons given by surgeons for not participating1.Lack of time 2.Lack of interest 3.Difficulty with REB:•Too many steps to obtain approval •No REB available in one community hospital, so approval from the principal investigator’s center was obtained. •The REB in one academic center rejected the project for lack of scientific background supporting sharing of confidential information on the Internet 4.No longer performing CEA 5.Awaiting new duplex scan in the operating room 6.First year in practice | | | Reasons given by surgeons for participating1.Ease of participation 2.Enthusiasm about sharing information with other surgeons 3.Eagerness to obtain documentation that could be presented to their hospital CMDP | | | | |
During the study, 560 patients had CEA performed in participating institutions, which was 47% of the 1196 CEAs performed in Quebec during MOLIERE. The Web-based registry was easily accessed by surgeons with data entry time of <2 minutes for most cases. Carotid endarterectomy was done in 279 of the 294 patients entered in the registry. The other 15 patients were 5 duplicates, and 10 were not operated on for various reasons, including no indication, 4; waiting list, 2; and 1 patient each because of refusal, death metastatic cancer, and myocardial infarction. All 279 CEA patients were followed up for 30 days. Despite having CEA in participating institutions, 281 patients were not enrolled in MOLIERE; of whom 145 were not enrolled by participating surgeon for various reasons that were not systematically recorded, and 136 patients were not enrolled in the database by 11 nonparticipating surgeons. Participating surgeons enrolled 66% (279 of 424) of their patients undergoing CEA in MOLIERE, with an inclusion rate varying from 6% to 100% per participating surgeon. Indications Before CEA, 44% of the 279 patients (32% women) enrolled were asymptomatic. Their mean age was 69 years (range, 46-91 years). Of the 157 patients (56%) who had a symptomatic stenosis, 48 (31%) had amaurosis, 59 (38%) had a transient ischemic attack, and 50 (32%) had a stroke. Patient comorbidities, imaging studies, medication, and operative details are reported in Table II. All patients enrolled were operated on under general anesthesia, 70% had a shunt, and 89% had a CEA with a patch angioplasty. | | | | Characteristics | All (N = 279) | Symptomatic (n = 157, 56%) | Asymptomatic (n = 122, 44%) | P | |
|---|
| Pre-op risk factors | | | | | | |  Age, years | | | | | | | ≥80, % | 11 | 14 | 4 | | | | 70-79, % | 38 | 35 | 40 | | | | 60-69, % | 33 | 29 | 39 | | | | 40-59, % | 19 | 22 | 17 | | | | Mean ± SD | | 69 ±10 | 68 ± 8 | NS | | | CAD, % | 53 | 52 | 55 | NS(0.625) | | | Hypertension, % | 76 | 76 | 76 | NS(0.259) | | | Smoking, % | 37 | 40 | 32 | NS(0.555) | | | Diabetes, % | | | | | | | Type 1 | 6 | 7 | 4 | NS(0.432) | | | Type II | 23 | 22 | 24 | NS(0.773) | | | Hyperlipidemia, % | 74 | 76 | 71 | NS(0.115) | | | Pre-op tests | | | | | | | Angiography, % | 36 | 34 | 39 | NS(0.335) | | | Doppler US imaging, % | 99 | 99 | 99 | NS(0.715) | | | MRI, % | 7 | 10 | 3 | .057 | | | CT scan, % | 41 | 54 | 24 | .0001 | | | Pre-op and peri-op drugs, % | | | | | | | Antiplateletsa | 96 | 97 | 95 | NS(0.461) | | | Statins | 79 | 80 | 77 | NS(0.515) | | | β-blockers | 54 | 54 | 54 | NS(0.976) | | | ACE inhibitors | 51 | 50 | 53 | NS(0.455) | | | Peri-op characteristics, % | | | | | | | CABG | 0.4 | 0.6 | 0 | NS(0.457) | | | General anesthesia | 100 | 100 | 100 | NS | | | Shunt | 70 | 66 | 74 | NS(0.175) | | | Patch | 89 | 90 | 90 | NS(0.299) | | | | |
| a Plavix (Sanofi-Aventis, Bridgewater, NJ) or aspirin, or both. |
Results and validation The overall SDR at 30 days for patients enrolled in MOLIERE was 1.8% (5 of 279), consisting of 3.2% for symptomatic patients (5 of 157) and 0% for asymptomatic patients (0 of 122), and the in-hospital cardiac complication rate was 5.7% (16 of 279). The average postoperative length of stay was 3.0 days (median, 2.0 days), and 13 patients were readmitted ≤30 days. Two patients presented with dysphagia, but no nerve injuries were reported. Detailed complications rates are reported in Table III. For patients who were enrolled in MOLIERE, validation after independent review of all charts was excellent, with no additional deaths or strokes than those reported by the surgeons. | | | | Complication | All, No. (%) | Symptomatic, No. (%) | Asymptomatic, No. (%) | |
|---|
| Total | 279(100) | 157(100) | 122(100) | | | Stroke or death rate | 5(1.8) | 5(3.2) | 0(0) | | | Stroke rate | 4(1.4) | 4(2.5) | 0(0) | | | Mortality rate | 2(0.7) | 2(1.3) | 0(0) | | | Cardiac complications rate | 16(5.7) | 6(3.2) | 10(8.2) | | | Acute coronary syndrome | 7(2.5) | 3(1.9) | 4(3.3) | | | Pulmonary edema | 3(1.1) | 0(0) | 3(2.5) | | | Arrhythmia | 8(2.9) | 3(1.9) | 5(4.1) | | | Reintervention | 1(0.4) | 1(0.6) | 0(0) | | | Intubation | 3(1.1) | 3(1.9) | 0(0) | | | Hypoglossal injury | 0(0) | 0(0) | | | | Post-op length of stay | | | | | | Mean, days | 3.0 | 3.4 | 2.6 | | | Median, days | 2.0 | 2.0 | 2.0 | | | | |
Results of CEA in participating institutions are reported in Table IV, Table V and in Fig 1, Fig 2. For patients operated on by participating surgeons, SDRs were not higher or statistically different for those patients not enrolled in MOLIERE compared with those enrolled in MOLIERE. The SDRs for patients operated on by nonparticipating surgeons were higher but not statistically different than the SDRs for patients operated on by participating surgeons (3.7% [5 of 136] vs 1.7% [7 of 424], P = .16). There was a trend toward a higher stroke rate for patients operated on by nonparticipating surgeons (3.7% [5 of 136] vs 1.2% [5 of 424], P = .056). Also, the stroke rate was significantly higher for asymptomatic patients operated on by nonparticipating surgeons (2.6% [1 of 39] vs 0% [0 of 188], P = .03). As depicted in Fig 2, all participating centers had SDRs within accepted standards. The SDRs per surgeon for symptomatic and asymptomatic patients were all within standards. | | | | Variable | Participating surgeons (n = 424), % | Nonparticipating surgeons (n = 136), % | P | |
|---|
| Stroke or death rate | | | | | | All patients | 1.7(7/424) | 3.7(5/136) | .16 | | | Asymptomatic | 0.5(1/188) | 2.6(1/39) | .22 | | | Symptomatic | 2.5(6/236) | 4.1(4/97) | .44 | | | Mortality rate | | | | | | All patients | 0.7(3/424) | 0.7(1/136) | 1.0 | | | Asymptomatic | 0.5(1/188) | 0(0/39) | .65 | | | Symptomatic | 0.8(2/236) | 1.0(1/97) | .87 | | | Stroke rate | | | | | | All patients | 1.2(5/424) | 3.7(5/136) | .056 | | | Asymptomatic | 0(0/188) | 2.6(1/39) | .03 | | | Symptomatic | 2.1(5/236) | 4.1(4/97) | .31 | | | Cardiac complication rate | | | | | | Overall | 7.1(30/424) | 8.8(12/136) | .50 | | | Acute coronary syndrome | 2.8(12/424) | 2.2(3/136) | .79 | | | Pulmonary edema | 2.4(10/424) | 5.9(8/136) | .04 | | | Arrhythmia | 4.0(17/424) | 2.2(3/136) | .32 | | | Reintervention | 1.4(6/424) | 2.9(4/136) | .24 | | | Post-op length of stay, days | | | | | | All patients, mean | 3.4 | 4.7 | .046 | | | All patients, median | 2.0 | 2.0 | | | | Symptomatic patients, mean | 3.5 | 5.4 | .035 | | | Asymptomatic patients, mean | 3.2 | 3.0 | .72 | | | | |
The postoperative length of stay was significantly longer for patients operated on by nonparticipating surgeons (mean, 4.7 vs 3.4 days, P = .046). This difference was also present when analyzing results of symptomatic patients only. The mean volume of CEAs per participating institution was 56.1 procedures (range, 7-113 procedures) during the 12 months of the study. The mean volume per surgeon was 16.5 procedures (range, 2-42; median, 15.5 procedures). Of the 34 surgeons in participating institutions, 10 had a volume of ≤10 CEAs and nine had a volume of ≥20. We could not demonstrate a relation between surgeon volume or center volume and SDRs. Discussion Many experts have called for independent audits of the outcomes of carotid surgery to ensure that the results from landmark trials are translated into effective clinical practice.7 The concept behind MOLIERE is that surgeon and neurologist involvement in a prospective manner is a prerequisite for them to evaluate, compare, and improve their practice.8 The finding of this study was that such an online prospective registry was as feasible for CEA as it is for other stroke prevention treatment.9 Participating surgeons spent <2 minutes online to enter patient data and were provided with accurate data on their SDRs. The surgeons and neurologist in each participating institution were at the heart of the process to evaluate and improve CEA results. Several surgeons from the province of Quebec have participated in the two major North American randomized clinical trials on CEA.1, 2 Many of them have also re-examined their own results by means of retrospective studies.10, 11 Nault et al12 showed that the rate of CEAs in Quebec was similar to that in Ontario during the 1990s,12 but no province-wide audit of outcomes and appropriateness has been performed. Because the benefit of CEA also depends on how the results of these clinical trials (defining the efficacy) are applied to actual clinical practice (the effectiveness of the procedure), the effectiveness of CEA in Quebec has not been demonstrated.13 It is with this understanding of the challenges created by evaluating effectiveness that we established, what is to our knowledge, the first Canadian online prospective study of CEAs involving community surgeons as well as surgeons from larger academic centers. The major advantage of our methodology is that it places surgeons at the center of the data analysis and allows a dynamic process of constant re-evaluation. Another advantage is that it enables the inclusion of remote locations in effectiveness research. Online databases have the advantage of being much less onerous and costly than conventional prospective studies: after the procedure, the surgeons spend about 2 minutes to enter the data for each category. Moreover, because the process is paperless, surgeons can access the database at different locations, at their leisure, 24 hours a day, 7 days a week, to complete their data entry in an efficient manner. We could not evaluate the province-wide effectiveness of MOLIERE because participation among institutions and surgeons performing CEA was lower than anticipated. The number of patients enrolled in MOLIERE was also lowered by a 65% inclusion rate by participating surgeons. Only a few surgeons were able to enroll all of their patients in MOLIERE. A government administrative database allowed us to determine that the number of CEAs during the 12 months of MOLIERE was nearly 1200. Thus, voluntary participation in this first project enrolled <25% of patients. In future projects, it should be possible to address most of the reasons stated by the surgeons for their lack of participation. This study has shown that sharing confidential information on the Internet can be done in a fast, reliable, and secure way, surgeons who participated in MOLIERE demonstrated adequate SDRs, and our audit was able to validate this method of data entry. Research Ethics Board approval was only necessary for this first study because external audits were required to access all CEA-linked hospital data. It will no longer be required in subsequent projects, and obtaining consent has been proven to be limiting factor in creating a registry.14 The validity of future projects would be better ensured by a multidisciplinary approach for data entry by a dedicated nurse, physician, or referring neurologist. This should also have an effect on compliance, because referring neurologists have a significant interest in demonstrating the usefulness of these interventions. In the future, to ensure complete data entry, neurologists could only refer patients to surgeons who agree to enter the patient information in the databank before CEA. In addition, vascular surgery societies could take the leadership of such projects, or hospital privileges could be pending on the surgeons participation. Most important, MOLIERE demonstrated that surgeons had adequate SDRs. In the past, improved CEA outcomes have been correlated with high surgeon volume and high hospital volume as well as surgeons specializing in vascular surgery.15, 16, 17, 18, 19, 20 Despite this, we believe that surgeons interested in their own surgery outcomes are an important confounding factor, as has been reported previously.11, 21 Although nonparticipating surgeons had adequate SDRs, the fact that there was a trend toward higher stroke rate in that group and that the centers and surgeons with the highest SDRs were also those who had a low participation in MOLIERE could be seen as an argument for MOLIERE. MOLIERE is a way to insure quality of care by identifying suboptimal results to improve them. For this reason, the scientific societies and the quality insurance body in each hospital should stimulate interest for future similar projects and increase hospital and surgeon participation. Complication rates could be underestimated when surgeons are the only ones evaluating their results. The integration of a multidisciplinary approach, including a neurologist, would allow more accurate estimation of complications. However, our validation process did not reveal any strokes that were missed during MOLIERE. Conclusion Van Der Fleuten22 defined five criteria for determining the usefulness of a particular method of assessment: reliability, validity, impact on future learning, acceptability to learners, and cost. We believe that MOLIERE is a new concept that meets all of these criteria and should be used to improve the quality of care of patients undergoing CEA. We would like to thank Lucie Daoust, executive director of the SSVQ, for organizing meetings. We also extend our gratitude to Dr Stephen M. Lewis for his critical comments and useful discussions, and to Pierre Gervais for helping us to write the consent form. The editorial assistance of Ovid Da Silva, Research Support Office, Research Centre, CHUM, is appreciated. Participating surgeons and hospitals Hôtel-Dieu de Sorel: Dr André Comtois; Centre hospitalier (CH) de Suroît: Dr Benoît Cartier; CH de Verdun: Dr Phillipe Richard; CH régional de Trois-Rivières: Dr Alain Desrosiers, Dr Jean-Yve Rivard, and Dr Daniel Bourgoin; Hôpital Hôtel-Dieu, CH de l’Université de Montréal (CHUM): Dr Stéphane Elkouri, Dr Nathalie Beaudoin, and Dr Luc Bruneau; CH Hôtel-Dieu d’Amos: Dr Éric Dupras and Dr Nicolas Aubrée; Cité de la Santé de Laval: Dr Jean-René Houle and Dr Guy Couture; CH universitaire de Québec/Hôpital St-François d’Assise: Dr Raymond Labbé, Dr Yves-Marie Dion, Dr Yvan Douville, Dr Nathalie Gilbert, and Dr Marie-France Guimond; CSSS de Gatineau, Hôpital de Hull: Dr Patrice Nault, Dr Louis-Phillipe Palerme, and Dr Khalal Khalaf; CH Régional de Lanaudière: Dr Michel Legault and Dr Charles Bossé. Author contributions Conception and design: PN, SE, MB Analysis and interpretation: PN, SE, VD, KO Data collection: PN, SE, VD, participating surgeons Writing the article: PN, SE, VD, MB Critical revision of the article: PN, SE, VD Final approval of the article: PN, SE, VD Statistical analysis: SE, VD, KO Obtained funding: PN, SE Overall responsibility: SE PN and SE contributed equally to this work. References 1. 1 Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis (North American Symptomatic Carotid Endarterectomy Trial Collaborators). N Engl J Med. 1991;325:445–453. MEDLINE 2. 2 Endarterectomy for asymptomatic carotid artery stenosis (Executive Committee for the Asymptomatic Carotid Atherosclerosis Study). JAMA. 1995;273:1421–1428. MEDLINE 3. 3Hobson RW. Randomized clinical trials: how will results influence clinical practice in the management of symptomatic and asymptomatic extracranial carotid occlusive disease?. 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22. 22Van Der Vleuten CPM. The assessment of professional competence: developments, research and practical implications. Adv Health Sci Ed. 1996;1:41–67. a Service de chirurgie vasculaire, Centre de santé et de services sociaux de Gatineau, Hôpital de Hull, University of Ottawa, Gatineau, Québec, Canada b Service de chirurgie vasculaire, Centre hospitalier de l’Université de Montréal (CHUM), Hôtel-Dieu, Montréal, Québec, Canada c Faculty of Medicine, McGill University, Montréal, Québec, Canada.  Correspondence: Stéphane Elkouri, MD, FRCSC, Service de chirurgie vasculaire, Centre Hospitalier de l’Université de Montréal, 3840 rue St-Urbain, Montreal, QC H2W 1T8, Canada.
Competition of interest: none. This study was supported in part by the Société des sciences vasculaires du Québec, the Blair-Gore Research Award from the Canadian Society of Vascular Surgeons (CSVS), and the Association des chirurgiens vasculaires du Québec (ACVQ). PII: S0741-5214(07)01894-0 doi:10.1016/j.jvs.2007.11.047 © 2008 The Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved. | |
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