Geographic disparity in kidney transplantation under KAS

Sheng Zhou, Allan B Massie, Xun Luo, Jessica M. Ruck, Eric K.H. Chow, Mary G. Bowring, Sunjae Bae, Dorry Segev, Sommer Elizabeth Gentry

Research output: Contribution to journalArticle


The Kidney Allocation System fundamentally altered kidney allocation, causing a substantial increase in regional and national sharing that we hypothesized might impact geographic disparities. We measured geographic disparity in deceased donor kidney transplant (DDKT) rate under KAS (6/1/2015-12/1/2016), and compared that with pre-KAS (6/1/2013-12/3/2014). We modeled DSA-level DDKT rates with multilevel Poisson regression, adjusting for allocation factors under KAS. Using the model we calculated a novel, improved metric of geographic disparity: the median incidence rate ratio (MIRR) of transplant rate, a measure of DSA-level variation that accounts for patient casemix and is robust to outlier values. Under KAS, MIRR was 1.751.811.86 for adults, meaning that similar candidates across different DSAs have a median 1.81-fold difference in DDKT rate. The impact of geography was greater than the impact of factors emphasized by KAS: having an EPTS score ≤20% was associated with a 1.40-fold increase (IRR = 1.351.401.45, P < .01) and a three-year dialysis vintage was associated with a 1.57-fold increase (IRR = 1.561.571.59, P < .001) in transplant rate. For pediatric candidates, MIRR was even more pronounced, at 1.661.922.27. There was no change in geographic disparities with KAS (P = .3). Despite extensive changes to kidney allocation under KAS, geography remains a primary determinant of access to DDKT.

Original languageEnglish (US)
JournalAmerican Journal of Transplantation
StateAccepted/In press - Jan 1 2018


  • Kidney transplantation/nephrology
  • Organ allocation
  • Organ procurement and allocation
  • Organ Procurement and Transplantation Network (OPTN)
  • Organ procurement organization
  • Scientific Registry for Transplant Recipients (SRTR)
  • Translational research/science
  • United Network for Organ Sharing (UNOS)

ASJC Scopus subject areas

  • Immunology and Allergy
  • Transplantation
  • Pharmacology (medical)

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