The impact of hospital size on national trends and outcomes in isolated open proximal aortic surgery

Objective: To determine the impact of hospital size on national trend estimates of isolated open proximal aortic surgery for benchmarking hospital performance. Methods: Patients age>18 years who underwent isolated open proximal aortic surgery for aneurysm and dissection from 2002 to 2014 were identified using the National Inpatient Sample. Concomitant valvular, vessel revascularization, re-do procedures, endovascular, and surgery for descending and thoracoabdominal aorta were excluded. Discharges were stratified by hospital size and analyzed using trend, multivariable regression, propensity-score matching analysis. Results: Over a 13-year period, 53,657 isolated open proximal aortic operations were performed nationally. Although the total number of operations/year increased (similar to 2.9%/year increase) and overall in-hospital mortality decreased (similar to 4%/year; both P<.001 for trend), these did not differ by hospital size (P>.05). Large hospitals treated more sicker and older patients but had shorter length of stay and lower hospital costs (both P<.001). Even after propensity-score matching, large hospital continued to demonstrate superior in-hospital outcomes, although only statistically for major in-hospital cardiac complications compared with non-large hospitals. In our subgroup analysis of dissection versus non-dissection cohort, inhospital mortality trends decreased only in the non-dissection cohort (P<.01) versus dissection cohort (P = .39), driven primarily by the impact of large hospitals (P<.01). Conclusions: This study demonstrates increasing volume and improving outcomes of isolated open proximal aortic surgeries nationally over the last decade regardless of hospital bed size. Moreover, the resource allocation of sicker patients to larger hospital resulted shorter length of stay and hospital costs, while maintaining similar operative mortality to small- and medium-sized hospitals.