Outcomes following emergent open repair for thoracic aortic dissection are improved at higher volume centers in direct admissions and transfers.

BACKGROUND: The purpose of this study is (1) to define the proportion of patients undergoing emergent open repair of thoracic aortic dissection admitted directly through the emergency room versus those transferred from outside hospitals and (2) to determine if a volume-outcomes relationship exists for those patients across admission types. METHODS: De-identified patient-level data was obtained from the Nationwide Inpatient Sample (2004-2008). Patients undergoing emergent aortic surgery for thoracic aortic dissection (n = 1,507) were identified by ICD-9 codes and stratified by annual center volume into low volume (≤5 cases/year) (n = 963; 63.9 %), intermediate volume (6-10 cases/year) (n = 370; 24.5 %), and high volume (≥11 cases/year) (n = 174; 11.6 %) groups. The analysis was further stratified by admission type: direct admission (DA), transfer admission (TA), and other. The primary outcome was in-hospital mortality. Multivariate logistic regression analysis was performed comparing outcomes between high vs low and high vs intermediate volume centers. RESULTS: Overall in-hospital mortality was 21.8 % (n = 328/1,507). Absolute percent mortality at high volume centers was significantly lower (12.6 %) than at medium (20.6 %) and low volume (23.9 %) centers. For DA patients, mortality was 10.6, 21.4, and 24.0 % for high, medium, and low volume centers respectively. For TA patients, mortality was 10.2, 12.7, and 23.5 % for high, medium, and low volume centers, respectively. Multivariate analysis suggested that patients in low volume center were more likely to die compared to high volume center (Odds Ratio 2.06, 95 % CI 1.25 - 3.38, p = 0.004). Admission source was not associated with increased mortality. CONCLUSIONS: Direct admissions comprise the largest proportion of dissections regardless of volume strata, and they comprise the largest proportion in the low and intermediate volume cohorts. Admission to low volume center is an independent risk factor for increased mortality. Patients transferred to high volume centers from low volume centers have similar outcome as direct admits in terms of mortality.

Outcomes following emergent open repair for thoracic aortic dissection are improved at higher volume centers.

BACKGROUND: Previous studies have demonstrated that patients undergoing complex surgical procedures at high-volume centers have improved outcomes. The goal of this study was to determine if this volume-outcomes relationship persists at a national level among patients undergoing emergent open repair for thoracic aortic dissection. METHODS: De-identified patient-level data were obtained from the Nationwide Inpatient Sample (2005 to 2008). Patients undergoing emergent aortic surgery for thoracic aortic dissection (n = 1230) were identified by ICD-9 codes and stratified by annual center volume into low volume (≤5 cases/year), intermediate volume (6 to 10 cases/year), and high volume (≥11 cases/year). The Deyo-Charlson co-morbidity score was used to adjust for differences in comorbidity between groups. Major outcomes of interest included: in-hospital morbidity and mortality, length of hospitalization, total hospital costs, and discharge disposition. RESULTS: There was a significant association between in-hospital mortality and center volume (p = 0.014), with low, intermediate, and high-volume centers having mortality rates of 23.4% (n = 187), 20.1% (n = 62), and 12.1% (n = 15), respectively. This relationship persisted when controlling for severity of co-morbid illness (p = 0.007). The number of complications per patient varied significantly by center volume (p = 0.044), with a higher proportion of patients at high-volume centers having no complications. Also, the highest proportion of home discharges was observed among patients at high-volume centers (p = 0.011). CONCLUSIONS: Survival following emergent open repair for thoracic aortic dissection was significantly greater at high-volume centers. These findings suggest that understanding the processes at high-volume centers that underlie this volume-outcomes relationship may improve in-hospital survival and postoperative complications.