Abstract Body: Background: Postoperative complication rates of carotid endarterectomy (CEA) and carotid artery stenting (CAS) for carotid artery stenosis are recommended to be maintained below a certain threshold. While the association between hospital volume and the complications has been reported, the situation is uncertain in Japan, one of the countries with the highest density of neuro-specialists. This study aimed to investigate the association between hospital volume and outcomes in patients who underwent CEA or CAS in Japan.
Methods: We retrospectively analyzed data from the Japanese nationwide inpatient database on CEA and CAS procedures performed between 2018 and 2021. Hospitals were categorized into four quartiles based on surgical volume, ranging from highest (Q1) to lowest (Q4), with approximately equal numbers of procedures in each quartile. The association between hospital volume and moderate to severe disability (modified Rankin scale > 2 at discharge), in-hospital mortality, perioperative stroke, perioperative pneumonia, and length of hospital stay (LHS) was investigated using multivariate logistic regression and other appropriate analyses.
Results: The analysis included 26,675 CEA or CAS procedures performed in 681 hospitals. The overall rates of disability, mortality, perioperative stroke, and pneumonia were 7.4%, 0.5%, 6.6%, and 5.0%, respectively. The rates of disability in Q1, Q2, Q3, and Q4 quartiles were 6.0%, 7.5%, 8.5%, and 7.4%, respectively (Table 1). After adjusting for covariates, Q3 and Q4 were associated with a higher risk of disability (Q3: odds ratio [OR] 1.41, 95% confidence interval [CI] 1.22 – 1.64, Q4: OR 1.41, 95% CI 1.00 - 1.37). Furthermore, Q2, Q3, and Q4 quartiles were associated with a higher risk of perioperative stroke (Q2: OR 1.46, 95% CI 1.26 - 1.70, Q3: OR 1.45, 95% CI 1.25 - 1.69, Q4: OR 2.04, 95% CI 1.77 – 2.36) and pneumonia (Q2: OR 2.01, 95% CI 1.68 – 2.39, Q3: OR 1.89, 95% CI 1.59 – 2.26, Q4: OR 1.79, 95% CI 1.50 – 2.14). The mortality rate was comparable among the four quartiles (Table 2). Additionally, Q2, Q3, and Q4 quartiles were associated with longer LHS. Similar results were observed in patients aged 80 and above.
Conclusions: Our findings suggest an association between lower hospital volume and poorer patient outcomes following CEA or CAS. This study indicates the importance of considering surgical volume as a factor to improve outcomes of CEA and CAS in Japan.