Objective: This study investigated risk factors for stroke or death after carotid endarterectomy (CEA) among hospitals of varying type and size participating in a regional quality improvement effort.
Methods: We reviewed 2714 patients undergoing 3092 primary CEAs (excluding combined procedures or redo CEA) at 11 hospitals in Northern New England from January 2003 through December 2007. Hospitals varied in size (25 to 615 beds) and comprised community and teaching hospitals. Fifty surgeons reported results to the database. Trained research personnel prospectively collected >70 demographic and clinical variables for each patient. Multivariate logistic regression models were used to generate odds ratios (ORs) and prediction models for the 30-day postoperative stroke or death rate.
Results: Across 3092 CEAs, there were 38 minor strokes, 14 major strokes, and eight deaths (5 stroke-related) < or =30 days of the index procedure (30-day stroke or death rate, 1.8%). In multivariate analyses, emergency CEA (OR, 7.0; 95% confidence interval [CI], 1.8-26.9; P = .004), contralateral internal carotid artery occlusion (OR, 2.8; 95% CI, 1.3-6.2; P = .009), preoperative ipsilateral cortical stroke (OR, 2.4; 95% CI, 1.1-5.1; P = .02), congestive heart failure (OR, 1.6; 95% CI, 1.1-2.4, P = .03), and age >70 (OR, 1.3; 95% CI, 0.8-2.3; P = .315) were associated with postoperative stroke or death. Preoperative antiplatelet therapy was protective (OR, 0.4; 95% CI, 0.2-0.9; P = .02). Risk of stroke or death varied from <1% in patients with no risk factors to nearly 5% with patients with > or =3 risk factors. Our risk prediction model had excellent correlation with observed results (r = 0.96) and reasonable discriminative ability (area under receiver operating characteristic curve, 0.71). Risks varied from <1% in asymptomatic patients with no risk factors to nearly 4% in patients with contralateral internal carotid artery occlusion (OR, 3.2; 95% CI, 1.3-8.1; P = .01) and age >70 (OR, 2.9; 95% CI, 1.0-4.9, P = .05). Two hospitals performed significantly better than expected. These differences were not attributable to surgeon or hospital volume.
Conclusion: Surgeons can "risk-stratify" preoperative patients by considering the variables (emergency procedure, contralateral internal carotid artery occlusion, preoperative ipsilateral cortical stroke, congestive heart failure, and age), reducing risk with antiplatelet agents, and informing patients more precisely about their risk of stroke or death after CEA. Risk prediction models can also be used to compare risk-adjusted outcomes between centers, identify best practices, and hopefully, improve overall results.