Age-based preferences in paired kidney exchange

We consider a model of Paired Kidney Exchange (PKE) with feasibility con-straints on the number of patient-donor pairs involved in exchanges. Patients’preferences are restricted so that patients prefer kidneys from compatible youngerdonors to kidneys from older donors. In this framework, patients with compati-ble donors may enroll on PKE programs to receive an organ with higher expectedgraft survival than that of their intended donor. PKE rules that satisfy individualrationality, efficiency, and strategy-proofness necessarily select pairwise exchanges.Such rules maximize the number of transplantations among pairs with the youngestdonors, and sequentially among pairs with donors of different age groups. JEL: C78;D02; D78; I10.