title: Temporal Analysis of Market Competition and Density in Renal Transplantation Volume and Outcome.
abstract: BACKGROUND
  Kidney transplant centers are distributed unevenly throughout 58 donor service areas (DSAs) in the United States. Market competition and transplant center density may affect transplantation access and outcomes. We evaluated the role of spatial organization of transplant centers in conjunction with market competition in the conduct of kidney transplantation.
  
  
  METHODS
  The Scientific Registry of Transplant Recipients was queried for market characteristics associated with kidney transplantation between 2003 and 2012. Market competition was calculated using the Herfindahl Hirschman Index. Kidney transplant centers were geocoded to measure spatial organization by the average nearest neighbor (ANN) method. Kidney quality was assessed by kidney donor risk index. A hierarchical negative binomial mixed effects model tested the relationship between market characteristics and annual kidney transplants by DSA.
  
  
  RESULTS
  About 152,071 kidney transplants were performed at 229 adult kidney transplant centers in 58 DSAs. Greater market competition was associated with kidney transplant center spatial clustering (P < 0.001). In multivariable analysis, more kidney transplant centers (incidence rate ratio [IRR], 1.04; P = 0.005), 100 more new listings (IRR, 1.02; P = 0.003), 100 more deceased donors (IRR, 1.23; P < 0.001), 100 more new dialysis registrants (IRR, 1.01; P < 0.001), and higher kidney donor risk index (IRR, 1.98; P < 0.001) were associated with increased kidney transplants.
  
  
  CONCLUSIONS
  After controlling for market characteristics, larger numbers of kidney transplant centers were associated with more kidney transplants and increased utilization of deceased donor kidneys. This underlines the importance of understanding geography as well as competition in improving access to kidney transplantation.
authors.affiliation: 1 Center for Surgery and Public Health, Brigham and Women's Hospital, Boston, MA. 2 Division of Transplant Surgery, Department of Surgery, Massachusetts General Hospital, Boston, MA. 3 Division of Vascular and Endovascular Surgery, Department of Surgery, Brigham and Women's Hospital, Boston, MA.
authors.forename: Joel T
authors.initials: JT
authors.lastname: Adler
authors.forename: Heidi
authors.initials: H
authors.lastname: Yeh
authors.forename: James F
authors.initials: JF
authors.lastname: Markmann
authors.forename: Louis L
authors.initials: LL
authors.lastname: Nguyen
mesh_terms: D064591:Allografts; D016009:Chi-Square Distribution; D003132:Commerce / Q000191:economics / Q000639:trends*; D016536:Competitive Medical Plans / Q000191:economics / Q000639:trends*; D004465:Economic Competition / Q000191:economics / Q000639:trends*; D006085:Graft Survival; D015276:Health Care Rationing / Q000639:trends; D019981:Health Care Sector / Q000191:economics / Q000639:trends*; D006297:Health Services Accessibility / Q000191:economics / Q000639:trends*; D006301:Health Services Needs and Demand / Q000639:trends; D054625:Healthcare Disparities / Q000191:economics / Q000639:trends*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000191:economics / Q000401:mortality / Q000601:surgery*; D016030:Kidney Transplantation / Q000009:adverse effects / Q000191:economics / Q000401:mortality / Q000639:trends*; D015999:Multivariate Analysis; D020380:Needs Assessment / Q000639:trends; D017064:Process Assessment, Health Care / Q000191:economics / Q000639:trends*; D016016:Proportional Hazards Models; D019984:Quality Indicators, Health Care / Q000639:trends; D012042:Registries; D012111:Residence Characteristics; D013997:Time Factors; D014019:Tissue Donors / Q000600:supply & distribution; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology