From the Midwestern Vascular Surgical Society Development of a validated model to predict 30-day stroke and 1-year survival after carotid endarterectomy for asymptomatic stenosis using the Vascular Quality Initiative

Objective: Carotid endarterectomy (CEA) has been shown to be an effective treatment for patients with asymptomatic carotid artery stenosis when perioperative stroke rates are low and patients survive long enough to benefit from the intervention. Our objective was to develop and to validate a simple risk prediction model for 30-day stroke and 1-year mortality to guide optimal selection of patients for CEA. Methods: Asymptomatic patients undergoing first-time elective CEA within the Vascular Quality Initiative (VQI) from 2010 to 2015 were selected. Outcome measures included any 30-day postoperative stroke and 1-year mortality. Patient demographics, comorbidities, carotid artery disease burden, and provider characteristics were evaluated to select a parsimonious clinical model for risk prediction using multivariable logistic regression. Internal validation was performed for stroke and split sample validation was done for 1-year survival to ensure generalizability. Results: We identified 31,939 patients for inclusion in the stroke analysis (2010-2015) and 24,086 patients for the mortality analysis (2010-2014). Both the 30-day stroke rate (0.9%) and 1-year mortality rate (3.4%) varied substantially across 265 VQI centers (range, 0%-8.3% and 0%-20%, respectively). Eleven significant factors were selected for the 30-day stroke risk prediction model (area under the receiver operating characteristic curve [AUC], 0.67). Internal validation demonstrated good discrimination (bias corrected AUC 1⁄4 0.652; calibration intercept and slope of 0.03 and 1.01, respectively). Similarly, 10 significant factors were selected for the 1-year mortality risk prediction model (AUC, 0.764). External validation demonstrated excellent discrimination and calibration (AUC, 0.764; 95% confidence interval, 0.72-0.80). Conclusions: Stroke and 1-year mortality rates after CEA for asymptomatic stenosis vary across VQI centers. We have developed a preoperative risk model that can be used to accurately estimate risk of perioperative stroke and 1-year mortality and to assist providers in selecting patients with asymptomatic stenosis who are most likely to benefit from CEA. (J Vasc Surg 2017;66:433-44.) Carotid endarterectomy (CEA) has been shown to reduce the risk of stroke or death in patients with severe carotid stenosis, and this benefit is most pronounced in patients with symptomatic disease. Both the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the European Carotid Surgery Trial (ECST) demonstrated a 3.8% to 8.3% per year reduction in any stroke or death with carotid surgery over medical treatment. The companion major randomized trials for he Division of Vascular and Endovascular Surgery, Mayo Clinic, Rocheshe Section of Vascular Surgery, University of Utah, Salt Lake City; the on of Vascular Surgery, University of Florida, Gainesville; the Division of lar Surgery and Endovascular Therapy, University of Alabama at ingham, Birmingham; the Division of Vascular and Endovascular ry, Massachussetts General Hospital, Boston; the Division of Vascular ry, Emory University, Atlanta; Northwest Community Hospital, Arlington ts; the Division of Vascular Surgery, Penn State Heart and Vascular ute, Hershey; Nashville Vascular & Vein Institute, Nashville; and the on of Vascular Surgery, Dartmouth-Hitchcock Medical Center, Lebanon. conflict of interest: none. asymptomatic disease also demonstrated a benefit of surgery with medical treatment over medical treatment alone, but the benefit was much smaller. The Asymptomatic Carotid Surgery Trial (ACST) and the Asymptomatic Carotid Atherosclerosis Study (ACAS) both demonstrated a reduction in stroke or death of approximately 1% per year. Current guidelines from the Society for Vascular Surgery recommend consideration of CEA for patients Presented at the Fortieth Annual Meeting of the Midwestern Vascular Surgical Society, Columbus, Ohio, September 8-10, 2016. Additional material for this article may be found online at www.jvascsurg. org. Correspondence: Randall R. DeMartino, MD, MS, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (e-mail: demartino.randall@mayo.edu). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright 2017 by the Society for Vascular Surgery. Published by Elsevier Inc. http://dx.doi. org/10.1016/j.jvs. 2017.03.427