Changes in characteristics of recovered U.S. deceased donor kidneys lead to large changes in KDRI-to-KDPI scaling over time.

The Kidney Donor Risk Index (KDRI) was introduced into the US kidney allocation system in 2014 as an estimate of the relative risk of post-transplant deceased donor kidney allograft failure in an adult recipient. It is scaled annually relative to the prior year's cohort of donors and converted to a percentile score known as the Kidney Donor Profile Index (KDPI), with higher scores suggesting shorter estimated function. This retrospective cohort study examined all deceased donor kidneys recovered for transplantation from 2016-2023 (N=187,817) to examine the extent to which the KDRI of organs with equivalent KDPI percentage score is changing. Median KDRI stayed constant or trended upwards annually-KDPI 50% kidneys in 2018 were KDRI 1.2 (0.96-1.56) compared to KDRI 1.4 (1.06-1.79) in 2023. The change in KDPI for identical donors ranged from 8% to 14%. KDPI 84% kidneys in 2023 had a KDRI of 1.97, which were KDPI 92% kidneys in 2016. The new KDRI equation, modeled without donor race and hepatitis C factors, showed greater clustering of KDRI values, consistent with a lower number of variables. Although kidneys may be represented by the same percentile score, the underlying drift of the KDRI may result in very different estimated longevity.