Risk scoring system to predict 3-year survival in patients treated for asymptomatic carotid stenosis

Objective: To identify risk factors and stratify their effect of compromising 3-year survival in patients treated for asymptomatic carotid disease based upon recently updated guidelines from the Society for Vascular Surgery. Methods: Outcomes of 506 patients who underwent carotid intervention for asymptomatic carotid disease (1999-2008) were analyzed. Hospital computerized medical records were reviewed. When local records were sparse, Social Security Death Index was queried to confirm mortality. Following multivariable Cox regression analysis, a score was assigned based on the calculated hazard ratio (HR) in the following fashion: HR 1.5-1.9 = 1 point; HR 2.0-3.0 = 2 points; and HR >3 = 3 points. The sum of those points comprised the final score for each patient. Kaplan-Meier analyses were then performed to delineate survival differences. Results: Seventy patients (13.83%) did not survive beyond 3 years after the procedure. Age >80 years (HR, 1.79; P = .05; score 1), diabetes mellitus (HR, 1.99; P < .05; score 1), coronary artery intervention (HR, 2.03; P < .01; score 2), severe chronic kidney disease defined as glomerular filtration rate <30 and not on dialysis (HR, 2.46; P = .03; score 2), dialysis patients (HR, 5.67; P = .001; score 3), and chronic obstructive pulmonary disease (HR, 3.53; P < .001; score 3) negatively influenced 3-year survival. Patients with score <= 2 experienced 3-year mortality of 6.0%, whereas score >2 was associated with 31.6% 3-year mortality (HR, 6.10; P < .001). The score value was not associated with the stroke rate at any time point. The resultant score was validated in a separate population of patients with symptomatic carotid disease. Conclusions: This easy predictive score underscores the association of medical risk factors with decreased 3-year survival. This finding may impact future clinical decisions for management of asymptomatic carotid disease.