ABSTRACT: National guidelines on carotid endarterectomy (CEA) for asymptomatic patients state that the procedure should be performed with a ? 3% risk of perioperative death or stroke. We developed and validated a multivariate model of risk of death or stroke within 30 days of CEA for asymptomatic disease and a related clinical prediction rule.We analyzed asymptomatic cases in a population-based cohort of CEAs performed in Medicare beneficiaries in New York State. Medical records were abstracted for sociodemographics, neurologic history, disease severity, diagnostic imaging data, comorbidities, and deaths and strokes within 30 days of surgery. We used multivariate logistic regression to identify independent predictors of perioperative death or stroke. The CEA-8 clinical risk score was derived from the final model.Among the 6553 patients, the mean age was 74 years, 55% were male, 62% had coronary artery disease, and 22% had a history of distant stroke or transient ischemic attack. The perioperative rate of death or stroke was 3.0%. Multivariable predictors of perioperative events were female sex (odds ratio [OR] = 1.5; 95% CI, 1.1 to 1.9), nonwhite race (OR = 1.8; 95% CI, 1.1 to 2.9), severe disability (OR = 3.7; 95% CI, 1.8 to 7.7), congestive heart failure (OR = 1.6; 95% CI, 1.1 to 2.4), coronary artery disease (OR = 1.6; 95% CI, 1.2 to 2.2), valvular heart disease (OR = 1.5; 95% CI, 1.1 to 2.3), a distant history of stroke or transient ischemic attack (OR = 1.5; 95% CI, 1.1 to 2.0), and a nonoperated stenosis ? 50% (OR = 1.8; 95% CI, 1.3 to 2.3). The CEA-8 risk score stratified patients with a predicted probability of death or stroke rate from 0.6% to 9.6%.Several sociodemographic, neurologic severity, and comorbidity factors predicted the risk of perioperative death or stroke in asymptomatic patients. The CEA-8 risk score can help clinicians calculate a predicted probability of complications for an individual patient to help inform the decision about revascularization.