Impact of center volume on outcomes of surgical repair for type A acute aortic dissections

Abstract

Background: Acute type A aortic dissection is a cardiovascular emergency requiring operative intervention. Despite advancements in operative technique and increased specialization of cardiovascular care, operative mortality, and morbidity after repair of type A aortic dissection remain high. Our aim was to assess national trends in outcomes of type A aortic dissection repair and the impact of institutional thoracic aortic repair volume on clinical outcomes and resource use in the United States.

Methods: Using the procedural and diagnostic codes of the International Classification of Diseases, Ninth Revision, we identified type A aortic dissection repairs from the 2005 to 2014 database of the National Inpatient Sample. Hospitals were classified into low-, medium- and high-volume tertiles based on annual incidence of thoracic aortic operations. Patient demographics and hospital characteristics, as well as outcomes including mortality, cost, and duration of stay, were evaluated using parametric tests for trends and the volume-outcome relationship. We used a multivariable-adjusted logistic regression model to identify factors associated with mortality.

Results: An estimated 25,231 patients received type A aortic dissection repair with an increasing temporal trend in volume and concomitant decrease in mortality. When stratified by hospital volume, 10,115 (40.1%), 8,194 (32.4%), and 6,920 (27.4%) underwent type A aortic dissection at low-volume, medium-volume, and high-volume, respectively. The unadjusted mortality rate in high-volume was the least (21.5% vs 16.8% vs 11.6% for low-volume, medium-volume, and high-volume, respectively; P < .001). Multivariable analysis revealed older age, lesser household incomes and comorbidities, including congestive heart failure (adjusted odds ratio 1.44; P < .001) and coagulopathy (adjusted odds ratio 1.33; P = .01) as statistically significant predictors of mortality; however, the risk-adjusted duration of stay (adjusted odds ratio 0.88; P = .06) was not different between low-volume and high-volume hospitals. After adjusting for patient and hospital characteristics, type A aortic dissection repair at low-volume hospitals was associated with increased likelihood of mortality compared with high-volume hospitals (adjusted odds ratio 2.10; P < .001). Patients undergoing type A aortic dissection repair at low-volume hospitals had increased odds of all complications including stroke, and respiratory complications compared than those at high-volume hospitals (P = .02, P < .001, and P < .001, respectively).

Conclusion: The volume of open surgical repair for type A aortic dissection in the United States has increased over the past decade, while mortality has decreased. Hospital aortic operative volume is strongly associated with outcomes for type A aortic dissection repair. Protocols for expeditious transfer of patients to high volume aortic centers may serve to further decrease the acute mortality and complications of this procedure.