Variation in death rate after abdominal aortic aneurysmectomy in the United States: impact of hospital volume, gender, and age

OBJECTIVE: To determine whether high-volume hospitals (HVHs) have lower in-hospital death rates after abdominal aortic aneurysm (AAA) repair compared with low-volume hospitals (LVHs). SUMMARY BACKGROUND DATA: Select statewide studies have shown that HVHs have superior outcomes compared with LVHs for AAA repair, but they may not be representative of the true volume-outcome relationship for the entire United States. METHODS: Patients undergoing repair of intact or ruptured AAAs in the Nationwide Inpatient Sample (NIS) for 1996 and 1997 were included (n = 13,887) for study. The NIS represents a 20% stratified random sample representative of all U.S. hospitals. Unadjusted and case mix-adjusted analyses were performed. RESULTS: The overall death rate was 3.8% for intact AAA repair and 47% for ruptured AAA repair. For repair of intact AAAs, HVHs had a lower death rate than LVHs. The death rate after repair of ruptured AAA was also slightly lower at HVHs. In a multivariate analysis adjusting for case mix, having surgery at an LVH was associated with a 56% increased risk of in-hospital death. Other independent risk factors for in-hospital death included female gender, age older than 65 years, aneurysm rupture, urgent or emergent admission, and comorbid disease. CONCLUSIONS: This study from a representative national database documents that HVHs have a significantly lower death rate than LVHs for repair of both intact and ruptured AAA. These data support the regionalization of patients to HVHs for AAA repair.