Prediction of benefit from carotid endarterectomy in individual patients: a risk-modelling study. European Carotid Surgery Trialists' Collaborative Group.
BACKGROUND
Carotid endarterectomy lowers the risk of carotid territory ipsilateral ischaemic stroke, and is the treatment of choice, in patients with recently symptomatic 70-99% carotid stenosis. However, the 3-year risk of stroke on medical treatment alone is only about 20%. We investigated whether the efficacy of endarterectomy would be improved if patients with a high risk of stroke on medical treatment and a low risk of operative stroke or death could be identified.


METHODS
We developed two prognostic models from data on patients with 0-69% carotid stenosis in the European Carotid Surgery Trial (ECST). The medical model predicted risk of ipsilateral carotid territory major ischaemic stroke (fatal or lasting longer than 7 days) on medical treatment and the surgical model predicted risk of major stroke and death within 30 days of endarterectomy. From these models we developed a prognostic score to identify patients with a high risk of stroke on medical treatment but a low operative risk. We validated the models and tested the scoring system on 990 ECST patients with 70-99% carotid stenosis assigned surgery (594) or medical treatment only (396).


RESULTS
When patients with 70-99% stenosis were stratified by the scoring system, which was based on seven independent prognostic factors, endarterectomy was beneficial in only 162 (16%) patients. The 5-year absolute risk of carotid territory ipsilateral major ischaemic stroke, operative major stroke, or death was lowered by 33% in the 16% of patients with a score of 4 or more (odds ratio 0.12 [95% CI 0.05-0.29], p<0.0001), but not in the other 828 (84%) patients (1.00 [0.65-1.54], p=0.7).


CONCLUSIONS
Many patients with recently symptomatic 70-99% carotid stenosis may not benefit from carotid endarterectomy. Validation of the predictive score is needed on external datasets, but risk-factor modelling could be useful to identify those patients in whom endarterectomy will be beneficial.
Rothwell
P M
PM
Department of Clinical Neurology, Radcliffe Infirmary, Oxford, UK. peter.rothwell@clneuro.ox.ac.uk
Warlow
C P
CP
D000206:Actuarial Analysis; D002545:Brain Ischemia / Q000517:prevention & control; D016893:Carotid Stenosis / Q000175:diagnosis* / Q000601:surgery; D002561:Cerebrovascular Disorders / Q000517:prevention & control*; D003661:Decision Support Techniques; D016894:Endarterectomy, Carotid; D006801:Humans; D008955:Models, Cardiovascular; D018579:Patient Selection; D011379:Prognosis; D016016:Proportional Hazards Models; D015203:Reproducibility of Results; D012306:Risk