Study Design

We performed a retrospective analysis of all patients in the Vascular Quality Initiative (VQI) who underwent primary CEA or redo CEA between January 1, 2003, and April 30, 2016. The setting was consecutive patients from academic and community hospitals across the United States. The VQI is a prospectively maintained database approved by the Society for Vascular Surgery (SVS) for patient safety and quality improvement purposes. It stipulates entry of all vascular cases performed at each participating hospital, contains patient-specific and procedure-specific data from multiple sites across all regions of the United States, and incorporates data on mortality from the Social Security Death Index. At the end of the study period, there were more than 370 hospitals and 2800 participating physicians in the VQI. Details of the data collection and validation process have been published previously. The present study was approved by the VQI Research Advisory Committee, and the Johns Hopkins Institutional Review Board waived the need for individual patient consent under the provisions for deidentified participant and quality improvement research.

Patients who underwent primary CEA or redo CEA were identified directly from the variables recorded in the VQI database. The relevant patient-related and procedure-related data assessed are listed in Table 1. The presence of a preoperative symptom was denoted as the occurrence of ipsilateral ocular or cortical transient ischemic attack or stroke within 6 months before surgery. The interval between symptom and surgery was also examined. Degree of stenosis was the most severe stenosis obtained from duplex, magnetic resonance angiography, computed tomographic angiography, or angiogram. The total number of CEAs performed by each surgeon was computed, and operators were subsequently grouped into quartiles of case volume.

Abbreviations: ASA, American Society of Anesthesiologists; CAD, coronary artery disease; CEA, carotid endarterectomy; CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; IQR, interquartile range; TIA, transient ischemic attack.

Postoperative (30-day) outcomes were ipsilateral stroke, death, myocardial infarction (MI), stroke or death, and stroke, death, or MI. One-year outcomes were stroke, death, and the composite of stroke or death. The individual and composite outcomes were chosen a priori based on clinical relevance. The composite outcome was included in this study because it is the counterfactual surrogate for “no adverse event after CEA,” which is the clinical objective of patient-centered care. Stroke was denoted as the occurrence of minor or major, ocular, or cortical stroke after surgery. Myocardial infarction was confirmed by electrocardiogram changes or critical elevation in troponins. Complications examined were cranial nerve injury, wound reexploration after closure, wound infection, return to the operating room for bleeding, neurologic or incision-related events, procedure-related arrhythmia, and reperfusion symptoms.