Monday, May 6, 2019

A (first) liver-kidney exchange

Here's a forthcoming paper in the American Journal of Transplantation:

Bi‐organ Paired Exchange – Sentinel Case of a Liver‐Kidney Swap
by Ana‐Marie Torres  Finesse Wong  Janine Sabatte‐Caspillo  Sandy Del Grosso John P Roberts  Nancy L Ascher  Chris E Freise  Brian K Lee
First published: 12 April 2019
https://doi.org/10.1111/ajt.15386

Abstract: "Organ transplantation is the optimal treatment for patients with ESLD and ESRD. However, due to the imbalance in the demand and supply of deceased organs, most transplant centers worldwide have consciously pursued a strategy for living donation. Paired exchanges were introduced as a means to bypass various biologic incompatibilities (blood‐ and tissue‐typing), while expanding the living donor pool. This shift in paradigm has introduced new ethical concerns that have hitherto been unaddressed, especially with non‐directed, altruistic living donors. So far, transplant communities have focused efforts on separate liver‐ and kidney‐paired exchanges, whereas the concept of a trans‐organ paired exchange has been theorized and could potentially facilitate a greater number of transplants. We describe the performance of the first successful liver‐kidney swap."
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The discussion of the ethical concerns mentioned in the abstract strike me as worth looking at, given that one of the authors, when she was president of the Transplantion Society, argued strenuously that poor patients should not be allowed to participate in American kidney exchange, for ethical reasons.

First, here are the practical steps they took:
"Our team debated the ethical underpinning of this swap. A discussion with the chair of the ethics committee at the time concluded that a full committee review was unnecessary."

Second, they considered the differential risks to the kidney and liver donors, and decided that this did not disallow the donations, since both kidney and liver donation is already accepted.

Finally they discuss the differential benefits to the liver and kidney recipients:
"Another area of contention is that donor-L’s recipient received remarkably less from a “life-enhancing” kidney transplant (rather than a truly “life-saving” liver transplant), despite the fact donor-L took on the substantially greater risk of donor hepatectomy. Our counterpoint is that the kidney recipient was spared from an extended dependency on dialysishad she stayed on the deceased donor waitlist (mortality on the kidney wait-list is 6-8% annually with a significant reduction in quality of life15,16). This does not even account for the superior allograft and patient survival outcomes that comes with a living vs. a deceased donor kidney transplant17. In fact, Merion18made the observation that the risk to patients on the kidney waitlist is not dissimilar to the liver waitlist mortality and reduction in quality of life for those with moderate MELD scores of 12-17. "

Fortunately for the patients involved, they decided that the benefits to the liver and kidney recipients were comparable. The implication is that if they had decided that the 'life-saving' benefits of a liver exceeded the 'life-enhancing' benefits of the kidney, then the exchange would have been unethical, and the ethical course of action would have been not to go ahead with it--which would likely have resulted in a quick death sentence for the liver patient, and perhaps a slower one for the kidney patient.

I'm glad that the dire decree was diverted.

It is this kind of ethical reasoning that led one of the authors to conclude that it would be unethical to go ahead with global kidney exchanges involving patient-donor pairs whose care had to be financed outside of their own countries' insurance coverage, so that, ethically, they could not be offered treatment even when financing was available. (It's lucky that the patients in this liver-kidney exchange apparently had good insurance, too.)
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The paper has an interesting back story in some speculative thoughts on market design.

The second reference in the paper is to a paper by computer scientists John Dickerson at Maryland and Tuomos Sandholm at CMU, proposing that multi-organ exchanges might substantially increase transplantation:
 Dickerson J, Sandholm T. Liver and multi-organ exchange. Journal of Artificial Intelligence Research. 2017;60:639

An unusual twist to the story is that it is the liver donor, eager to help her mother get a kidney transplant, who read the Dickerson-Sandholm paper and proposed the idea to the docs at UCSF.


Here's a press release from CMU, celebrating the event, and Sandholm's contributions:
Computer Science Idea Triggers First Kidney-Liver Transplant Swap
Sandholm says multi-organ exchanges could boost number of transplants
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Update: here's a May 11 story in the Washington Post

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