Prediction of benefit from carotid endarterectomy in individual patients: a risk-modelling study

Background Carotid endarterectomy lowers the risk of carotid territory ipsi lateral ischaemic stroke, and is the treatment of choice, in patients with recently symptomatic 70-99% carotid stenosis. However, the 3-year risk of s troke on medical treatment alone is only about 20%. We investigated whether the efficacy of endarterectomy would be improved if patients with a high r isk of stroke on medical treatment and a low risk of operative stroke or de ath 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 stro ke (fatal or lasting longer than 7 days) on medical treatment and the surgi cal model predicted risk of major stroke and death within 30 days of endart erectomy. From these models we developed a prognostic score to identify pat ients with a high risk of stroke on medical treatment but a low operative r isk. We validated the models and tested the scoring system on 990 ECST pati ents with 70-99% carotid stenosis assigned surgery (594) or medical treatme nt only (396). Findings When patients with 70-99% stenosis were stratified by the scoring system, which was based on seven independent prl,gnostic factors, endartere ctomy was beneficial in only 162 (16%) patients. The 5-year absolute risk o f carotid territory ipsilateral major ischaemic stroke, operative major str oke, or death was lowered by 33% in the 16% of patients with a sr:ore of 4 or more (odds ratio 0.12 [95% CI 0.05-0.29], p<0.0001), but not in the othe r 828 (84%) patients (1.00 [0.45-1.54], p=0.7). Interpretation Many patients with recently symptomatic 70-99% carotid steno sis may not benefit from carotid endarterectomy. Validation of the predicti ve score is needed on external datasets, but risk-factor modelling could be useful to identify those patients in whom endarterectomy will be beneficia l.