Background: Periprocedural outcome has been extensively investigated in patients undergoing carotid artery stenting. However, risk factors contributing to long-term mortality have not been comprehensively assessed. We aimed to establish a validated clinical risk score for long-term mortality in patients after carotid artery stenting.
Methods and results: Two independent cohorts after successful carotid artery stenting (602 and 552 patients) were prospectively investigated. Multivariable Cox regression and bootstrap variable selection were used to select the best-fitting multivariable model. The mortality rate was 35% in the derivation and 39% in the validation cohort during a median follow-up of 6.5 and 7.4 years, respectively. The following variables were identified as most robust risk factors in the derivation cohort: age, heart failure, diabetes mellitus, relative lymphocyte count, prothrombin time, peripheral artery disease, and contralateral carotid occlusion. A weighted multimarker risk score yielded an area under the receiver operating characteristic curve of 0.79 in the derivation (P<0.001) and of 0.69 (P<0.001) in the validation cohort. In comparison, the best area under the receiver operating characteristic curves for single risk factors were 0.67 and 0.63, respectively. For optimal clinical use, a simplified risk score was also developed, which discriminated very well from very low to very high risk. The risk of all-cause mortality ranged from 8% for a score of 1 to 93% for a score of 7 (P<0.001) in the derivation and from 11% to 100% in the validation cohort (P<0.001).
Conclusions: A multimarker risk score outperformed the prognostic value of single risk factors for the prediction of long-term mortality.