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Kidney Week

Abstract: TH-PO1172

Are We There Yet? Meeting the Goal of Increased Utility Under the New Kidney Allocation System

Session Information

Category: Transplantation

  • 1901 Transplantation: Basic


  • Wherry, Kael, University of Minnesota, Minneapolis, Minnesota, United States
  • Mcgovern, Patricia M., University of Minnesota, Minneapolis, Minnesota, United States
  • Kunct, Karen, University of Minnesota, Minneapolis, Minnesota, United States

The Kidney Allocation System (KAS) was designed to improve limitations of the previous deceased donor kidney transplant (DDKT) allocation algorithm in the United States. A key feature in the KAS is a scoring system that matches longest recipient life expectancy with longest donor graft survival expectancy, trading fairness for utility by prioritizing the best kidneys to the healthiest candidates. This study compared outcomes between patients aged 50 years and younger (<50) versus patients aged 51 and older (>50), the patient groups specifically impacted by the longevity matching scores.


This study used patient-level data from the Scientific Registry of Transplant Recipients. Relative risk of DDKT and waitlist mortality or removal from the waitlist due to deteriorating health was estimated in the pre- versus post-KAS eras with logistic regression models including fixed effects for organ supply and several patient clinical and demographic characteristics. The post-KAS era was divided into four distinct periods (0-6 months, 6-12 months, 12-24 months, 24-36 months) to assess trends over time. Survival benefit of transplant compared to remaining on the waitlist by KAS era and age group was estimated with a Cox proportional hazard regression model.


This study included 239,265 incident and prevalent adult candidates on the kidney transplant waitlist between December 4, 2011 and December 3, 2017. Relative risk of DDKT for younger candidates versus older candidates was greatest in the first six months post-KAS compared to the pre-KAS era (1.17 95% CI 1.11-1.23). Candidates aged <50 years and >50 years had 1.15 (95% CI 1.00-1.30) and 1.19 (95% CI 1.07-1.30) times the risk of mortality on the waitlist or removal due to deteriorating condition in the third year post-KAS compared to the pre-KAS era, respectively. There was no difference in relative risk of mortality within age group in the first two years post KAS compared to the pre-KAS era. The survival benefit of DDKT compared to remaining on the waitlist was greater in the post-KAS era compared to the pre-KAS era among both age groups.


This study suggests the KAS is at least partly meeting the goal of improved utility in DDKT in the first years of implementation; however, inefficiencies in DDKT still exist. Continued analysis is needed to assess the sustained benefit of the KAS.


  • Other U.S. Government Support