Impact of kidney allocation system 250 policy on 1-year graft loss

A new deceased donor kidney allocation system (KAS250) was implemented in March 2021 that prioritizes recipients within a 250-nautical mile radius of the donor hospital. KAS250 was implemented to reduce geographic disparities in access to kidney transplantation. Studies have shown an increase in cold ischemia time (CIT) after KAS250 implementation but the impact on graft outcomes is unknown. Utilizing data from the Scientific Registry of Transplant Recipients, we estimated cause-specific hazards of 1-year death-censored graft loss (DCGL) and all-cause graft loss (ACGL) due to KAS250 for the post-KAS250 period (April 2021 to December 2022; N = 28 584) compared to the pre-KAS250 period (January 2017 to December 2018; N = 23 798). We found that the post-KAS250 period had higher DCGL (hazard ratio 1.14; 95% CI 1.02-1.26; P = 0.0187) and ACGL (hazard ratio 1.22; 95% CI 1.13-1.31, P < .0001). Mediation analysis showed that CIT indirectly mediated 45.54% and 15.73% of KAS250 policy's effect on DCGL and ACGL, respectively. In conclusion, short-term graft outcomes in the post-KAS250 era are inferior to those in the pre-KAS250 era, with the worsening CIT being a significant contributor. Therefore, further adjustments to both the policy and transplant practices should be considered to further optimize equity and outcomes.