Kidney Exchange in Dynamic Sparse Heterogenous Pools

TL;DR

This paper analyzes how different matching algorithms and waiting periods in kidney exchange pools affect the number of transplants, showing that longer waits and complex cycles significantly increase matches.

Contribution

It introduces a theoretical and computational analysis of dynamic matching algorithms in kidney exchange pools, highlighting the benefits of longer waits and complex cycles.

Findings

2-way cycles require very long waits for significant gains

Allowing 3-way cycles increases matches with shorter waits

Using non-simultaneous chains further boosts match numbers

Abstract

Current kidney exchange pools are of moderate size and thin, as they consist of many highly sensitized patients. Creating a thicker pool can be done by waiting for many pairs to arrive. We analyze a simple class of matching algorithms that search periodically for allocations. We find that if only 2-way cycles are conducted, in order to gain a significant amount of matches over the online scenario (matching each time a new incompatible pair joins the pool) the waiting period should be "very long". If 3-way cycles are also allowed we find regimes in which waiting for a short period also increases the number of matches considerably. Finally, a significant increase of matches can be obtained by using even one non-simultaneous chain while still matching in an online fashion. Our theoretical findings and data-driven computational experiments lead to policy recommendations.