Tuesday, October 21, 2014: 10:30 AM

Yun Zhang, PhD1, Shoou-Yih Lee, PhD2, Ted A. Skolarus, MD, MPH3, John T. Wei, MD, MS4 and Brent K. Hollenbeck, MD, MS1, (1)Institute for Healthcare Policy and Innovation, Ann Arbor, MI, (2)Department of Health Management and Policy, Ann Arbor, MI, (3)VA Center for Clinical Management Research, Ann Arbor, MI, (4)University of Michigan, Ann Arbor, MI


The consistent empirical findings of a positive relationship between hospital surgical volume and outcome suggests a learning effect on the improvement of surgical practice – “practice makes perfect.”. The relationship provides a justification for concentrating surgical procedures in a limited number of high-volume hospitals (i.e., regionalization) as a way to improve surgical outcomes. In this study, we examine the degree of regionalization of 8 high-risk surgeries across states. Moreover, we optimize a statewide regionalization policy for those high-risk surgeries and assess its impact on in-hospital mortality and operating hospital capacity.


Our data are the 2003-2010 State Inpatient Database in 11 states. The 8 high-risk surgeries include repair of abdominal aortic aneurysm (AAA), aortic-valve replacement, coronary-artery bypass grafting (CABG), carotid endarterectomy, cystectomy, esophagectomy, lung resection, and pancreatectomy. For each surgery, we estimate a hospital-level learning curve to characterize the volume and in-hospital mortality relation. Next, using the curve, we solve best regionalization policy that minimizes in-hospital mortality. The gap between in-hospital mortality under existent patient referral pattern and that under best regionalization reflects regionalization degree of the surgery. We repeat the analysis across surgeries and states.



Regionalization of aortic-valve replacement varied the least across the 11 states (see Figure); its mortality gap between existent referral pattern and best regionalization ranged from 16.0% in New York state to 22.2% in California (6.2% difference). In contrast, regionalization of pancreatectomy varied the most across the 11 states (see Figure); its mortality gap between existent referral pattern and best regionalization ranged from 40.5% in Maryland to 66.5% in California (26.0% difference). Regionalization could avoid 16,719 deaths among 1,730,168 cases for the 8 surgeries in the 11 states during 2003-2010. Specifically, regionalization could avoid the most deaths (2,654 among 318,506 cases) for carotid endarterectomy and the least deaths (891 among 25,030 cases) for esophagectomy.  Across the 8 surgeries, observed operating hospitals were 4.5 (for CABG) to 21.0 (for lung resection) times greater than optimal numbers under best regionalization.


Regionalization of high risk surgeries varies significantly in the US. Statewide regionalization has the potential to significantly reduce in-hospital mortality. From a mortality reduction perspective, there exists an overcapacity of caring hospitals for high risk surgeries.