More Competitive Markets Are Associated with Lower Mortality After Complex Aortic Surgery

Centralizing complex aortic surgery within regional hubs can improve outcomes due to well-demonstrated volume-outcome relationships. However, regional hubs frequently exist in dense urban areas, where competitive markets have broadly demonstrated inferior outcomes in vascular surgery. Here, we evaluate the impact of local market competition on perioperative outcomes in complex aortic surgery specifically. A retrospective review was conducted of all Vascular Quality Initiative (VQI) patients between 2013 and 2022 undergoing index complex endovascular aortic repair (EVAR) including internal iliac or renovisceral vessel involvement, complex thoracic endovascular aortic repair (TEVAR) including zone 0 to 2 proximal extent or branched devices, and complex open aortic repair (OAR) including suprarenal or higher clamp sites. Market competition was determined using the Herfindahl-Hirschman Index (HHI), a sum-of-squares of surgeon-level market share within blinded VQI regions. Higher HHI indicates lower competition. Kruskal-Wallis and χ2 tests assessed relationships between HHI intervals and baseline characteristics. HHI tertiles (low [0-0.0460], medium [0.046-0.069], and high [0.069-0.294]) and clinical, demographic, and other hospital characteristics were included in multivariable logistic regression models for mortality and readmission, with Poisson and Cox models for postoperative length-of-stay and survival. A total of 10,868 patients underwent complex aortic surgery in the VQI: 1238 complex EVARs, 7062 complex TEVARs, and 2568 complex OARs. More patients were treated in low HHI regions (5574 vs 3145 with medium HHI and 2149 with high HHI). Median age was 75 years, and 68.4% were male. White patients were more common with low HHI (84.4% vs 75.3% for high HHI; P < .001), as were open repairs (25.7% vs 15.9% for high HHI; P < .001). Comorbidities and preoperative medications were broadly similar across HHI intervals. Lower 30-day mortality was seen with low HHI (23.7% for low HHI, 25.9% for medium, and 25.9% for high; P = .03). In multivariable logistic models, compared with low HHI, medium HHI was associated with 1.39-fold greater odds of 30-day mortality (95% confidence interval [CI], 1.21-1.60; P < .001). High HHI trended towards greater mortality (odds ratio [OR], 1.20; 95% CI, 0.98-1.45; P = .07). Low HHI was associated with longer length-of-stay (rate ratio [RR] for medium HHI, 0.94; 95% CI, 0.92-96; P < .001; RR for high HHI, 0.84; 95% CI, 0.81-0.86; P < .001). HHI intervals demonstrated no long-term survival effect. More competitive regions demonstrate lower 30-day mortality after complex aortic surgery despite higher levels of open repairs. Further efforts should identify factors driving this difference to improve the distribution of high-quality complex aortic care.