| Study characteristics |
| Methods |
RCT
ITT analysis
Censored at crossover
Mean follow‐up: 1.5 years for stenosis, ECST‐measured 50% to 99%, NASCET‐measured 70% to 99%
Mean follow‐up: 5 years for NASCET‐measured stenosis 30% to 69%, ECST‐measured 58% to 82%
Minimum follow‐up: 4 months |
| Participants |
2926 participants
North America
106 centres
Sex: either
Age: less than 80 years before 1991, no age limitation afterwards
Qualifying event: ischaemic cerebrovascular event (TIA, transient monocular blindness, or minor non‐disabling ischaemic stroke), ipsilateral to carotid stenosis, within 4 months of randomisation
Criteria: inclusion and exclusion criteria
Degree of stenosis: 0% to 99% (NASCET equation), 40% to 99% (ECST equation)
Baseline demographics: mean age 66 years, 69% male, myocardial infarction 18%, angina 24%, diabetes19%
Qualifying event: TIA 68%, stroke 32% |
| Interventions |
'Carotid endarterectomy as soon as possible' versus 'no carotid endarterectomy' for stenosis ECST‐measured 30% to 69%, NASCET‐measured 70% to 99%
'Carotid endarterectomy as soon as possible' versus 'carotid endarterectomy in the event of progression to NASCET‐measured > 70% stenosis, ECST‐measured 58% to 82% stenosis'.
Co‐interventions: protocolised recommendations for both groups
Co‐interventions described and similar
Crossover: medical to surgical 6.3% (ECST‐measured 50% to 99%, NASCET‐measured 70% to 99%); medical to surgical 7% (ECST‐measured 58% to 82%, NASCET‐measured 30% to 69%); a further 7.9% in this study crossed over in accordance with protocol for progression of stenosis or after a primary event; surgical to medical 0.3% (ECST‐measured 50% to 99%, NASCET‐measured 70% to 99%); surgical to medical 1.9 % (ECST‐measured 58% to 82%, NASCET‐measured 30% to 69%) |
| Outcomes |
Primary outcome: ipsilateral stroke
Other outcomes: ipsilateral stroke; death; death or stroke; ipsilateral fatal stroke; ipsilateral major stroke; fatal stroke; major stroke; death or major stroke
NINDS stroke definition
Major or disabling stroke was defined as a Rankin score of at least 3 that persisted at 90 days |
| Funding source |
National Institute of Neurological Disorders and Stroke, USA |
| Notes |
Adequate concealment
Patients not blinded
Clinicians not blinded
External blinded review of outcomes
Follow‐up 100%
Demographics: adequately reported and similar
Principal investigator: Dr Barnett, John P Robarts Research Institute, PO Box 5015, 100 Perth Drive, London, ON N6A 5K8, Canada |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Low risk |
Quote: "Patients were randomly assigned to medical or surgical therapy" |
| Allocation concealment (selection bias) |
Low risk |
Quote: "Patients were randomly assigned to medical or surgical therapy by means of a centralized computer‐generated algorithm with stratification according to center" |
| Blinding of participants and personnel (performance bias)
All outcomes |
High risk |
Comment: because of the nature of the intervention (surgical and non‐surgical groups), this RCT could not be blinded for surgeons or participants |
| Blinding of outcome assessment (detection bias)
All outcomes |
Low risk |
Quote: "Outcome events were assessed in four steps: first, by the participating neurologist and surgeon; second, by the neurologists at the study data center; third, by the members of the steering committee, in a blinded manner; and fourth, by blinded external adjudicators" |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
Comment: no participants were lost to follow‐up |
| Selective reporting (reporting bias) |
Low risk |
Comment: authors published findings on all the study outcomes (predefined) |
| Other bias |
Low risk |
|
