Improving Kidney Donations to Save Lives

kidney transplant

Approximately 100,000 patients with end-stage renal disease are currently on the waiting list in the United States for a deceased donor kidney transplant. Fewer than 11,000 of these patients will receive one of these kidneys; about 4,000 patients will die each year while waiting; and another 2,500 will be removed from the waiting list because they will become too sick to be viable candidates for a transplant. Indeed, this is a growing problem since the length of the waiting list increases by about 7000 patients every year. About 6000 patients will receive a living donor’s kidney this year, and over 500 of these living kidney transplants will be the result of kidney exchange, also called kidney paired donation.

Kidney exchange allows potential living donors whose kidney is incompatible with their intended recipient to nevertheless donate a kidney so that their recipient receives a compatible one from another donor. This is done by exchange between two or more incompatible patient-donor pairs. Non-directed living donors who decide to donate without having a particular intended recipient can also initiate a chain of transplants involving multiple incompatible pairs.  Between 2000-2006, fewer than 170 kidney exchanges were performed in the United States. 

The Alliance for Paired Donation is a small non-profit organization that organizes multi-hospital kidney exchanges. It adopted integer programming to identify optimal sets of disjoint exchanges. Until 2007 cycles and chains were implemented simultaneously, meaning that a three-way exchange required six operating rooms and six surgical teams (for three nephrectomies and three transplants). The reason that all surgeries in a cyclic exchange among patient-donor pairs are conducted simultaneously is because a broken link had the potential to impose a tragic cost on one of the pairs.

In 2007, the Alliance for Paired Donation was the first kidney exchange organization to introduce non-simultaneous (and hence potentially long) chains. Chains can be conducted so that every patient receives a kidney no later than his intended donor donates a kidney. Following the first non-simultaneous chain that included 16 transplants, further sophisticated integer programming techniques were developed to optimize within the new, rich set of exchanges.

Overcoming political opposition and skepticism, the new approach has also been adopted by other leading exchange programs. The Alliance for Paired Donation has saved more than 220 lives through its kidney exchange program, with more than 75% of these achieved through long non-simultaneous chains. Transplanting a single patient saves Medicare more than $270,000 over five years.

The technology and methods pioneered by APD have been adopted by other transplant exchanges, resulting in thousands of lives already saved, with the promise of increasing impact in coming years. The percentage of transplants from non-simultaneous chains has already reached more than 6% of the total number of transplants from live donors (including directed living donors) in the last year, and substantially increasing the number of the very highly sensitized transplanted patients.

Operations research and market design has played a crucial role in increasing the number of transplants, both in the Alliance for Paired Donation and in the other leading exchange programs.