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 L. Segev, Sommer E. Gentry

Research output: Contribution to journalArticlepeer-review


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)
Pages (from-to)1415-1423
Number of pages9
JournalAmerican Journal of Transplantation
Issue number6
StatePublished - Jun 2018


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

ASJC Scopus subject areas

  • Immunology and Allergy
  • Transplantation
  • Pharmacology (medical)


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