Allocating kidneys in optimized heterogeneous circles.

Area of Science:

• Transplant surgery
• Organ allocation policy
• Health services research

Background:

• The Organ Procurement and Transplant Network (OPTN) is implementing a policy to allocate deceased donor kidneys within fixed 250-nm radius circles around donor hospitals.
• Geographic disparities in kidney transplant rates persist due to uneven distribution of deceased donor kidney supply and demand nationwide.
• Homogeneous allocation circles may not effectively mitigate these geographic inequalities.

Purpose of the Study:

• To design unique, heterogeneous kidney allocation circles that minimize geographic variation in kidney supply and demand ratios across transplant centers.
• To compare the effectiveness of these novel heterogeneous circles against fixed-distance homogeneous circles in addressing supply/demand imbalances.
• To evaluate the impact of heterogeneous circles on average kidney travel distance.

Main Methods:

• Utilized Scientific Registry of Transplant Recipients data from 2016-2019.
• Employed an integer programming model to design heterogeneous circles with radii ranging from 100 to 500 nm.
• Weighted organ demand by candidate wait time to prioritize those who have waited longer.
• Compared supply/demand ratios and average travel distances between heterogeneous and fixed-distance homogeneous circles (250 nm and 500 nm).

Main Results:

• Heterogeneous circles significantly reduced supply/demand ratio variation compared to homogeneous circles.
• For heterogeneous circles, supply/demand ratios ranged from 0.06 to 0.13 kidneys per wait-year.
• Fixed-distance homogeneous circles showed wider ranges: 0.04 to 0.47 (250 nm) and 0.05 to 0.15 (500 nm).
• Approximately 40% of the optimized heterogeneous circles were 250 nm or smaller.
• Average kidney travel distance was 173 nm for heterogeneous circles, versus 134 nm for 250 nm homogeneous and 269 nm for 500 nm homogeneous circles.

Conclusions:

• Heterogeneous kidney allocation circles effectively reduce geographic disparities in organ availability compared to fixed-distance homogeneous circles.
• This approach balances kidney supply and demand more equitably across transplant centers.
• Heterogeneous circles achieve improved equity while maintaining reasonable organ travel distances, optimizing the national kidney allocation system.