title: Impact of geography on organ allocation: Beyond the distance to the transplantation center.
abstract: OBJECTIVE
  To illustrate the application and utility of Geographic Information System (GIS) in exploring patterns of liver transplantation. Specifically, we aim to describe the geographic distribution of transplant registrations and identify disparities in access to liver transplantation across United Network of Organ Sharing (UNOS) region 1.
  
  
  METHODS
  Based on UNOS data, the number of listed transplant candidates by ZIP code from 2003 to 2012 for Region 1 was obtained. Choropleth (color-coded) maps were used to visualize the geographic distribution of transplant registrations across the region. Spatial interaction analysis was used to analyze the geographic pattern of total transplant registrations by ZIP code. Factors tested included ZIP code log population and log distance from each ZIP code to the nearest transplant center; ZIP code population density; distance from the nearest city over 50000; and dummy variables for state residence and location in the southern portion of the region.
  
  
  RESULTS
  Visualization of transplant registrations revealed geographic disparities in organ allocation across Region 1. The total number of registrations was highest in the southern portion of the region. Spatial interaction analysis, after adjusting for the size of the underlying population, revealed statistically significant clustering of high and low rates in several geographic areas could not be predicted based solely on distance to the transplant center or density of population.
  
  
  CONCLUSIONS
  GIS represents a new method to evaluate the access to liver transplantation within one region and can be used to identify the presence of disparities and reasons for their existence in order to alleviate them.
authors.affiliation: Rony Ghaoui, Division of Gastroenterology, Baystate Medical Center, Tufts University School of Medicine, Springfield, MA 01199, United States.
authors.forename: Rony
authors.initials: R
authors.lastname: Ghaoui
authors.affiliation: Rony Ghaoui, Division of Gastroenterology, Baystate Medical Center, Tufts University School of Medicine, Springfield, MA 01199, United States.
authors.forename: Jane
authors.initials: J
authors.lastname: Garb
authors.affiliation: Rony Ghaoui, Division of Gastroenterology, Baystate Medical Center, Tufts University School of Medicine, Springfield, MA 01199, United States.
authors.forename: Fredric
authors.initials: F
authors.lastname: Gordon
authors.affiliation: Rony Ghaoui, Division of Gastroenterology, Baystate Medical Center, Tufts University School of Medicine, Springfield, MA 01199, United States.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Pomfret
keywords: Health geographic’s; Healthcare disparities; Outcome research