A Risk Prediction Model for Determining Appropriateness of CEA in Patients with Asymptomatic Carotid Artery Stenosis

Objective: The benefit of carotid endarterectomy (CEA) over medical therapy in patients with asymptomatic carotid artery stenosis is predicated upon a life expectancy of at least 5 years after the procedure. The goal of this study was to create a scoring system for prediction of 5-year survival after CEA that can be used to triage patients with ACAS. Methods: All patients who underwent CEA for severe asymptomatic carotid stenosis from 1989 to 2005 were identified. Long-term survival was determined by a review of hospital records and the social security death index. Because all patients had at least 5-year follow-up, a logistic regression of predictors of survival at 5 years was performed and the odds ratios associated with particular significant comorbidities were used to create a scoring system to predict survival. The scoring system was then validated within the cohort using the Hosmer-Lemeshow Test and a derivation/validation receiver operating characteristic (ROC) curve. Results: There were 2004 CEA performed in 1791 patients. The average follow-up was 130 ± 49 months. The clinical profile of the cohort data included 84% hypertension, 56% coronary artery disease (CAD), 24% diabetes, and 71% on statins. The 30-day stroke rate was 1.1% and the death rate was 0.7%. The actual 5-year survival was 73%. Logistic regression yielded the following predictors of mortality: age (by decade) (odds ratio [OR] = 1.8, P < 0.0001), CAD (OR = 1.5, P = 0.0007), chronic obstructive pulmonary disease (OR = 2.5; P < 0.0001), diabetes (OR = 1.7, P < 0.0001), neck radiation (OR = 2.6, P = 0.005), no statin (OR = 2.1, P < 0.0001), and creatinine more than 1.5 (OR = 2.6, P < 0.0001). These variables were then assigned a hierarchal point scoring system in accordance with the OR value. The 5-year survival based on the scoring system was as follows: 0 to 5 points = 92.5%, 6 to 8 points = 83.6%, 9 to 11 points = 63.7%, 12 to 14 points = 46.5%, and more than 15 points = 33.8%. The Hosmer-Lemeshow test validated the scoring system (P = 0.26) and there was no difference in the ROC curves (C statistic = 0.74 vs 0.73). Conclusions: This validated scoring system can be a useful tool for determining which patients are likely to benefit most from CEA based on the probability of long-term survival. Given that the 5-year survival of patients in the medical arm of the asymptomatic CEA trials was 60% to 70%, it is reasonable to conclude that patients who score 0 to 8 points are excellent candidates for CEA whereas most patients with ≥12 points should be managed with medical therapy alone.