Ontario registry risk model provides ‘reliable’ predictions of stroke, death following carotid endarterectomy


The Ontario carotid endarterectomy registry (OCER) model was found to be the most reliable predictor of stroke or death after carotid endarterectomy (CEA) among 17 models assessed. This was the primary finding of a systematic review published in Stroke by Michiel Poorthuis, MD, of the department of neurology at University Medical Center Utrecht, The Netherlands, and colleagues.

The risk of procedural death or stroke determines the net benefit of CEA. Current guidelines recommend CEA if 30-day risks are <6% and >3% for symptomatic stenosis and asymptomatic stenosis in patients. The systematic review by Poorthuis and team—whose senior authorship included Marc Schermerhorn, MD, chief of vascular and endovascular surgery at Beth Israel Deaconess Medical Center in Boston—aimed to identify and externally validate prediction models for procedural death or stroke, in a registry of patients from the U.S.

A total of 788 reports were screened, with 15 studies consisting of 17 prediction models of procedural outcomes after CEA included within the systematic review, through MEDLINE and EMBASE. The models were validated with patient data from those who received CEA from 2011–2017 in the American College of Surgeons National Surgical Quality Improvement Program. Using C statistics and calibration graphically, discrimination was assessed. Additionally, the number of patients with predicted risks that exceeded recommended thresholds of procedural risks to perform CEA were determined.

Out of the 17 prediction models, nine were developed in populations including both asymptomatic and symptomatic patients, two in symptomatic and five in asymptomatic populations. A total of 26,293 patients who underwent CEA were included within the external validation cohort. Of the patients studied, 11,035 experienced symptomatic carotid stenosis, with 14,772 asymptomatic patients.

Out of the 26,293 patients, 702 (2.7%) developed a stroke or died within 30 days. The range of C statistics varied across all patients (0.52–0.64). Symptomatic patients’ C statistics were between 0.51–0.59 and 0.49–0.58 in asymptomatic patients. The OCER model, consisting of symptomatic status, diabetes, heart failure, and contralateral occlusion as predictors, had C statistic of 0.64, with the strongest concordance between predicted and observed risks. Furthermore, the findings displayed the OCER model identified 4.5% of symptomatic and 2.1% of asymptomatic patients with procedural risks that exceeded recommended thresholds. In conclusion, out of the externally validated prediction models (n=17), the OCER model enabled the most reliable predictions of death and stroke in patients following CEA. The model can also inform patients about the procedural hazards of CEA, and help create focus towards patients who would benefit greatly, the authors add.


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