Age Distribution Aged Carotid Stenosis--epidemiology Endarterectomy, Carotid--adverse effects Female Follow-Up Studies Health Care Surveys Hospital Mortality Hospitalization--statistics & numerical data Humans Male Middle Aged Ontario--epidemiology Patient Selection Population Surveillance Practice Patterns, Physicians'--statistics & numerical data Risk Factors Sex Distribution Stroke--epidemiology Surveys and Questionnaires Treatment Outcome Women's Health