Market Competition and Density in Liver Transplantation: Relationship to Volume and Outcomes Joel T Adler, MD, MPH, Heidi Yeh, MD, James F Markmann, MD, PhD, FACS, Louis L Nguyen, MD, MBA, MPH, FACS BACKGROUND: Liver transplantation centers are unevenly distributed within the Donor Service Areas (DSAs) of the United States. This study assessed how market competition and liver transplantation center density are associated with liver transplantation volume within individual DSAs. STUDY DESIGN: We conducted a retrospective cohort study of 53,156 adult liver transplants in 45 DSAs with 110 transplantation centers identified from the Scientific Registry of Transplant Recipients between 2003 and 2012. The following measures were derived annually for each DSA: market competi- tion using the Herfindahl Hirschman Index, transplantation center density by the Average Near- est Neighbor method, liver quality by the Liver Donor Risk Index, and patient risk by the Model for End-Stage Liver Disease. A hierarchical mixed effects negative binomial regression model of the relationship between liver transplants and market factors was created annually. Patient and graft survival were investigated with a Cox proportional hazards model. RESULTS: Transplantation center density was associated with market competition (p < 0.0001), listings for organ transplantation (p < 0.0001), and Model for End-Stage Liver Disease at trans- plantation (p ¼ 0.0005). More liver transplantation centers (incidence rate ratio [IRR] ¼ 1.03; p ¼ 0.04), greater market competition (IRR ¼ 1.36; p ¼ 0.02), increased listings (IRR ¼ 1.14; p < 0.0001), more donors (IRR ¼ 1.24; p < 0.0001), and higher Liver Donor Risk Index (IRR ¼ 3.35; p < 0.0001) were associated with more transplants. No market variables were associated with increased mortality after transplantation. CONCLUSIONS: After controlling for demographic and market factors, a greater concentration of centers was associated with more liver transplants without impacting overall survival. These results war- rant additional investigation into the relationship between geospatial factors and liver trans- plantation volume with consideration for the optimization of scarce resources. (J Am Coll Surg 2015;221:524e531. Ó 2015 by the American College of Surgeons) Liver transplantation is a profound and life-saving inter- vention for patients with end-stage liver disease, but geographic disparities in access to transplantation exist in the United States. 1-4 Across the country, liver transplan- tation centers are distributed unevenly throughout the 58 legislatively defined Donor Service Areas (DSAs), which generally serve as the first geographic border for organ allocation and distribution. Coupled with the current or- gan allocation system, this geographic variation in trans- plantation center distribution leads to disparities in access to organ transplantation and graft outcomes. 1-4 As organs are initially allocated within a DSA, considering each DSA as an individual market can be a useful method for understanding transplantation practices and outcomes in the United States. Disclosure Information: Nothing to disclose. Disclaimer: The data reported here have been supplied by the Minneapolis Medical Research Foundation as the contractor for the Scientific Registry of Transplant Recipients (SRTR). The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy of or interpretation by the SRTR or the United States Government. Presented at the 95th Annual Meeting of the New England Surgical Society, Stowe, VT, September 2014. Received October 6, 2014; Revised April 9, 2015; Accepted April 15, 2015. From the Center for Surgery and Public Health (Adler, Nguyen), Division of Vascular and Endovascular Surgery, Department of Surgery (Nguyen), Brigham and Women’s Hospital, and Division of Transplant Surgery, Department of Surgery, Massachusetts General Hospital (Adler, Yeh, Markmann), Boston, MA. Correspondence address: Louis L Nguyen, MD, MBA, MPH, FACS, Divi- sion of Vascular and Endovascular Surgery and the Center for Surgery and Public Health, Brigham and Women’s Hospital, 75 Francis St, Boston, MA 02115. email: llnguyen@partners.org 524 ª 2015 by the American College of Surgeons Published by Elsevier Inc. http://dx.doi.org/10.1016/j.jamcollsurg.2015.04.018 ISSN 1072-7515/15