Carotid artery stenting compared with endarterectomy in patients with symptomatic carotid stenosis (International Carotid Stenting Study): a randomised controlled trial with cost-effectiveness analysis

Abstract

BackgroundCarotid artery stenting (CAS) is an alternative to carotid endarterectomy (CEA) for the treatment of carotid stenosis, but safety and long-term efficacy were uncertain.ObjectiveTo compare the risks, benefits and cost-effectiveness of CAS versus CEA for symptomatic carotid stenosis.DesignInternational, multicentre, randomised controlled, open, prospective clinical trial.SettingHospitals at 50 centres worldwide.ParticipantsPatients older than 40 years of age with symptomatic atheromatous carotid artery stenosis.InterventionsPatients were randomly allocated stenting or endarterectomy using a computerised service and followed for up to 10 years.Main outcome measuresThe primary outcome measure was the long-term rate of fatal or disabling stroke, analysed by intention to treat (ITT). Disability was assessed using the modified Rankin Scale (mRS). A cost–utility analysis estimating mean costs and quality-adjusted life-years (QALYs) was calculated over a 5-year time horizon.ResultsA total of 1713 patients were randomised but three withdrew consent immediately, leaving 1710 for ITT analysis (853 were assigned to stenting and 857 were assigned to endarterectomy). The incidence of stroke, death or procedural myocardial infarction (MI) within 120 days of treatment was 8.5% in the CAS group versus 5.2% in the CEA group (72 vs. 44 events) [hazard ratio (HR) 1.69, 95% confidence interval (CI) 1.16 to 2.45;p = 0.006]. In the analysis restricted to patients who completed stenting, age independently predicted the risk of stroke, death or MI within 30 days of CAS (relative risk increase 1.17% per 5 years of age, 95% CI 1.01% to 1.37%). Use of an open-cell stent conferred higher risk than a closed-cell stent (relative risk 1.92, 95% CI 1.11 to 3.33), but use of a cerebral protection device did not modify the risk. CAS was associated with a higher risk of stroke in patients with an age-related white-matter changes score of 7 or more (HR 2.98, 95% CI 1.29 to 6.93;p = 0.011). After completion of follow-up with a median of 4.2 years, the number of patients with fatal or disabling stroke in the CAS and CEA groups (52 vs. 49), and the cumulative 5-year risk did not differ significantly (6.4% vs. 6.5%) (HR 1.06, 95% CI 0.72 to 1.57;p = 0.776). Stroke of any severity was more frequent in the CAS group (15.2% vs. 9.4% in the CEA group) (HR 1.712, 95% CI 1.280 to 2.300;p < 0.001). There was no significant difference in long-term rates of severe carotid restenosis or occlusion (10.8% in the CAS group vs. 8.6% in the CEA group) (HR 1.25, 95% CI 0.89 to 1.75;p = 0.20). There was no difference in the distribution of mRS scores at 1-year, 5-year or final follow-up. There were no differences in costs or QALYs between the treatments.LimitationsPatients and investigators were not blinded to treatment allocation. Interventionists’ experience of stenting was less than that of surgeons with endarterectomy. Data on costs of managing strokes were not collected.ConclusionsThe functional outcome after stenting is similar to endarterectomy, but stenting is associated with a small increase in the risk of non-disabling stroke. The choice between stenting and endarterectomy should take into account the procedural risks related to individual patient characteristics. Future studies should include measurement of cognitive function, assessment of carotid plaque morphology and identification of clinical characteristics that determine benefit from revascularisation.Trial registrationCurrent Controlled Trials ISRCTN25337470.FundingThis project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full inHealth Technology Assessment; Vol. 20, No. 20. See the NIHR Journal Library website for further project information. Further funding was provided by the Medical Research Council, Stroke Association, Sanofi-Synthélabo and the European Union.