BACKGROUND: Implementation of the Kidney Allocation System (KAS) changed how kidneys are allocated and the information on which organ utilization decisions are based. We aimed to evaluate how KAS implementation changed kidney utilization and recipient outcomes.

MATERIAL AND METHODS: Using the United Network for Organ Sharing database, we identified recipients of kidney transplants from donors with kidney donor profile index (KDPI) of 61–90% in the 5-years pre- and 18-months post-KAS implementation and examined patient and graft survival and donor kidney discard rates based on standard criteria donor (SCD) or expanded criteria donor (ECD) status.

RESULTS: The proportion of ECD kidneys was unchanged pre- versus post-KAS. Post-KAS, SCD kidneys were less likely to be transplanted into young recipients while ECD kidneys were more likely to be transplanted. SCD kidneys in the post-KAS period conferred a 1.42 (95% CI: 1.18–1.73) times higher adjusted mortality and 2% lower 1-year survival (94.2% vs. 96.2%, P<0.001) but had unchanged graft failure compared to pre-KAS. For ECD kidneys, there was no difference in mortality or graft survival. The discard rate increased after KAS for both SCD and ECD kidneys (P<0.05) but was not different between SCD and ECD kidneys for any KDPI group.

CONCLUSIONS: After KAS implementation, patient survival for recipients of SCD kidneys was significantly worse.

Keywords: Kidney Transplantation, Patient Selection, Tissue and Organ Procurement