Association of carotid endarterectomy at low-volume centers with higher likelihood of major complications and nonroutine discharge

Abstract

OBJECTIVE Carotid artery stenosis (CAS) is associated with an annual stroke risk of 2%–5%, and revascularization with carotid endarterectomy (CEA) can reduce this risk. While studies have demonstrated that hospital CEA volume is associated with mortality and myocardial infarction, CEA volume cutoffs in studies are relatively arbitrary, and no specific analyses on broad complications and discharge disposition have been performed. In this study, the authors systematically set out to identify a cutoff at which CEA procedural volume was significantly associated with major complications and nonroutine discharge. METHODS Asymptomatic and symptomatic CAS patients undergoing CEA were retrospectively identified in the Nationwide Readmissions Database (2010–2018). The association of CEA volume with outcomes was explored as a continuous variable using locally estimated scatterplot smoothing. The identified volume cutoff was used to generate dichotomous volume cohorts, and multivariate analyses of patient and hospital characteristics were conducted to evaluate the association of CEA volume with major complications and discharge disposition. RESULTS Between 2010 and 2018, 308,933 asymptomatic and 32,877 symptomatic patients underwent CEA. Analysis of CEA volume with outcomes as a continuous variable demonstrated that an increase in volume was associated with a lower risk until a volume of approximately 7 cases per year (20th percentile). A total of 6702 (2.2%) asymptomatic and 1040 (3.2%) symptomatic patients were treated at the bottom 20% of hospital procedure volume. Increased rates of complications were seen at low-volume centers among asymptomatic (3.66% vs 2.77%) and symptomatic (7.4% vs 6.87%) patients. Asymptomatic patients treated at low-volume centers had an increased likelihood of major complications (OR 1.26, 95% CI 1.07–1.49; p = 0.007) and nonroutine discharge (OR 1.36, 95% CI 1.24–1.50; p < 0.0001). Symptomatic patients treated at low-volume centers were also more likely to experience major complications (OR 1.47, 95% CI 1.07–2.02; p = 0.02) and nonroutine discharge (OR 1.26, 95% CI 1.07–1.47; p = 0.005). Mortality rates were similar between low- and high-volume hospitals among asymptomatic (0.36% and 0.32%, respectively) and symptomatic (1.06% and 1.49%, respectively) patients, while volume was not significantly associated with mortality among asymptomatic (OR 1.06, 95% CI 0.67–1.65; p = 0.81) and symptomatic (OR 0.81, 95% CI 0.43–1.54; p = 0.52) patients in multivariate analysis. CONCLUSIONS CEA patients, asymptomatic or symptomatic, are at a higher risk of major complications and nonroutine discharge at low-volume centers. Analysis of CEA as a continuous variable demonstrated a cutoff at 7 cases per year, and further study may identify factors associated with improved outcome at the lowest-volume centers.