Transplant science, transplant politics , and public perception--the case of living-donor livers

 Liver transplants from living donors are on the increase in the U.S., so liver transplants are coming to more closely resemble kidney transplants.  Apparently that comes with some of the politics that I've witnessed involving kidney transplants. At least that's what the article below, by a very large and distinguished set of American authors, seems to be dealing with, in this critique of a paper published in a European journal. (It's unusual to see a question about scientific integrity highlighted in the title of an academic paper...). Apparently the title of the paper being criticized received news coverage unfavorable to transplantation, and not justified by the data being reported.

Emamaullee, J., Heimbach, J.K., Olthoff, K.M., Pomfret, E.A., Roberts, J.P., Selzner, N. and NALLDIG Consortium, 2022. Assessment of long‐term outcomes post living liver donation highlights the importance of scientific integrity when presenting transplant registry data. American Journal of Transplantation, online early,  First published: 30 March 2022 https://doi.org/10.1111/ajt.17045

"Abstract: Living donor liver transplantation has expanded in recent years, particularly in North America. As experience with this procedure has matured over the last 25 years, centers are increasingly faced with potential living donors who are more medically complex. As donors move through the evaluation process, completing the informed consent process continues to be challenged by a paucity of granular data demonstrating long-term outcomes and overall safety specifically in the otherwise ‘healthy’ living liver donor population. Two recently published studies examined long-term outcomes post-living liver donation using Korean registry data and reported similar results, with excellent overall survival when compared to appropriately matched controls. However, the authors of these studies were presented differently, with one reporting an alarmist view based on one aspect of a suboptimal analysis approach using an inappropriate comparator group. Herein, the North American Living Liver Donor Innovation Group (NALLDIG) consortium discusses these two studies and their potential impact on living liver donation in North America, ultimately highlighting the importance of scientific integrity in data presentation and dissemination when using transplant registry data."

"Recently, in the Journal of Hepatology, Choi and colleagues published a noteworthy study of long-term outcomes of Korean living liver donors, titled “Outcomes of living liver donors are worse than those of matched healthy controls.”

...

"Although careful examination of long-term outcomes for living liver donors is essential, and the South Korean population is an excellent population in which to conduct these analyses given the relative frequency of living donor liver transplantation, the current study suffers from a serious design flaw which makes interpretation of the data very challenging, as highlighted in detail in the letter to the editor from the Toronto group.4 Indeed, the Control Group I “heathy population” is actually healthier than the living liver donors given that “the proportion of individuals with Charlson Comorbidity Index ≥1, diabetes, hypertension, or depression in the living liver donor group was higher than that in the matched healthy group (Control Group I).” They then use this heavily weighted (10:1 match) heathier group to demonstrate, unsurprisingly, a subtle but statistically worse outcome in the living liver donor group, hence the title of the paper. 

...

"Unfortunately, both the manuscript title, “Outcomes of living liver donors are worse than those of matched healthy controls” and the lay summary, which is intended for the public at large are highly misleading, given this lack of a matched control group. This leads to confusion and uncertainty not only for those within the medical community but also for prior donors as well as for future potential living donors and their recipients. One may wonder whether these choices were made to drive the sensationalism of the media on this topic particularly in some European countries where practice of LDLT is no longer pursued for a variety of reasons including overall skepticism that the procedure is truly safe for living donors.

...

"Journal editorial boards bear the responsibility of arranging high-quality, expert peer review. The dramatic increase in the volume of manuscripts submissions during COVID-19 pandemic has strained many editorial board members and reviewers, likely resulting in publication of studies of variable rigor.16 In parallel, careful assessment of statistical techniques and interpretation of analyses has become an integral part of the review process. Many journals now employ full-time statistical editors, which has enabled identification of serious flaws in experimental design including insufficient study power, missing data, or inappropriate use of statistical tests or models.17 Editors must also critically assess the power of a provocative manuscript title, as initially it may grab the reader's attention and can bias the reader's interpretation and impression. Journals also must be willing to publish studies even when results are disappointing and/or controversial. The transplant community should continue to carefully assess and respond to any work that may dampen enthusiasm for living donation or living donor liver transplantation."

"Execution by organ procurement: Breaching the dead donor rule in China," by Matthew P. Robertson, and Jacob Lavee in the AJT

 Prior to 2015, it was legal in China to transplant organs recovered from executed prisoners. When I visited China in those days to talk about kidney transplantation from living donors, it was sometimes pointed out to me that, as an American, I shouldn't object to the Chinese use of executed prisoner organs, because we also had capital punishment in the US, but we "wasted the organs."  I replied that in the US we had both capital punishment and transplantation, but were trying to limit one and increase the other, and that I didn’t think that either would be improved by linking it to the other.  

So here's a just-published retrospective paper looking at Chinese language transplant reports prior to 2015, which identifies at least some instances that it regards as "execution completed by organ procurement."

Execution by organ procurement: Breaching the dead donor rule in China, by Matthew P. Robertson1, and Jacob Lavee2, American Journal of Transplantation, Early View, First published: 04 April 2022 https://doi.org/10.1111/ajt.16969

1 Australian National University |  Victims of Communism Memorial Foundation, Washington, D.C., USA

2 Heart Transplantation Unit, Leviev Cardiothoracic Center, Sheba Medical Center, Faculty of Medicine, Tel Aviv University, Ramat Gan, Israel

Abstract: The dead donor rule is fundamental to transplant ethics. The rule states that organ procurement must not commence until the donor is both dead and formally pronounced so, and by the same token, that procurement of organs must not cause the death of the donor. In a separate area of medical practice, there has been intense controversy around the participation of physicians in the execution of capital prisoners. These two apparently disparate topics converge in a unique case: the intimate involvement of transplant surgeons in China in the execution of prisoners via the procurement of organs. We use computational text analysis to conduct a forensic review of 2838 papers drawn from a dataset of 124 770 Chinese-language transplant publications. Our algorithm searched for evidence of problematic declarations of brain death during organ procurement. We find evidence in 71 of these reports, spread nationwide, that brain death could not have properly been declared. In these cases, the removal of the heart during organ procurement must have been the proximate cause of the donor's death. Because these organ donors could only have been prisoners, our findings strongly suggest that physicians in the People's Republic of China have participated in executions by organ removal.

"how should we understand the physician's role in a context where executed prisoners are the primary source of transplant organs? Might the transplant surgeon become the de facto executioner? Evidence suggestive of such behavior has emerged over many years from the People's Republic of China (PRC).8-14 To investigate these reports, this paper uses computational methods to examine 2838 Chinese transplant-related medical papers published in scientific journals, systematically collecting data and testing hypotheses about this practice. By scrutinizing the clinical procedures around intubation and ventilation of donors, declaration of brain death, and commencement of organ procurement surgery, we contribute substantial new evidence to questions about the role of PRC physicians in state executions.

...

"The data we rely on in this paper involves transplant surgeries from 1980 to 2015. During this period, there was no voluntary donation system and very few voluntary donors. According to three official sources, including the current leader of the transplant sector, the number of voluntary (i.e., non-prisoner) organ donors in China cumulatively as of 2009 was either 120 or 130,30-32 representing only about 0.3% of the 120 000 organs officially reported to be transplanted during the same period (on the assumption that each voluntary donor gave three organs).18, 33, 34 The leader of China's transplant sector wrote in 2007 that effectively 95% of all organ transplants were from prisoners.35 According to official statements, it was only in 2014 that a national organ allocation system could be used by citizens.36

...

"Procuring vital organs from prisoners demands close cooperation between the executioner and the transplant team. The state's role is to administer death, while the physician's role is to procure a viable organ. If the execution is carried out without heed to the clinical demands of the transplant, the organs may be spoiled. Yet if the transplant team becomes too involved, they risk becoming the executioners.

"Our concern is whether the transplant surgeons establish first that the prisoners are dead before procuring their hearts and lungs. This translates into two empirical questions: (1) Is the donor intubated only after they are pronounced brain dead? And (2) Is the donor intubated by the procurement team as part of the procurement operation? If either were affirmative the declaration of brain death could not have met internationally accepted standards because brain death can only be determined on a fully ventilated patient. Rather, the cause of death would have been organ procurement.

...

"We define as problematic any BDD in which the report states that the donor was intubated after the declaration of brain death, and/or the donor was intubated immediately before organ procurement, as part of the procurement operation, or the donor was ventilated by face mask only.

...

"The number of studies with descriptions of problematic BDD was 71, published between 1980 and 2015. Problematic BDD occurred at 56 hospitals (of which 12 were military) in 33 cities across 15 provinces. 

...

"We have documented 71 descriptions of problematic brain death declaration prior to heart and lung procurement. From these reports, we infer that violations of the DDR took place: given that the donors could not have been brain dead before organ procurement, the declaration of brain death could not have been medically sound. It follows that in these cases death must have been caused by the surgeons procuring the organ.

"The 71 papers we identify almost certainly involved breaches of the DDR because in each case the surgery, as described, precluded a legitimate determination of brain death, an essential part of which is the performance of the apnea test, which in turn necessitates an intubated and ventilated patient. In the cases where a face mask was used instead of intubation48, 49—or a rapid tracheotomy was followed immediately by intubation,50 or where intubation took place after sternal incision as surgeons examined the beating heart44—the lack of prior determination of brain death is even more apparent.

"If indeed these papers document breaches of the DDR during organ procurement from prisoners as we argue, how were these donors prepared for organ procurement? The textual data in the cases we examine is silent on the matter. Taiwan is the only other country we are aware of where death penalty prisoners’ vital organs have been used following execution. This reportedly took place both during the 1990s and then once more in March 2011.51, 52

...

"The PRC papers we have identified do not describe how the donor was incapacitated before procurement, and the data is consistent with multiple plausible scenarios. These range from a bullet to the prisoner's head at an execution site before they are rushed to the hospital, like Tsai's description, or a general anesthetic delivered in the operating room directly before procurement. Paul et al. have previously proposed a hybrid of these scenarios to explain PRC transplant activity: a lethal injection, with execution completed by organ procurement. 

...

"We think that our failure to identify more DDR violations relates to the difficulty of detecting them in the first instance, not to the absence of actual DDR violations in either the literature or practice. Our choice to tightly focus only on papers that made explicit reports of apparent DDR violations likely limited the number of problematic papers we ultimately identified.

...

"As of 2021, China's organ transplant professionals have improved their reputation with their international peers. This is principally based on their claims to have ceased the use of prisoners as organ donors in 2015."

Süleyman Kerimov defends his dissertation

 Süleyman Kerimov defended his dissertation yesterday, in Stanford's MS&E department. He studies matching, and will teach at Rice next year.

His main advisors are both named Itai.

These are the papers he spoke about:

• Dynamic Matching: Characterizing and Achieving Constant Regret, with Itai Ashlagi and Itai Gurvich, . [pdf] [SSRN]


• Scrip Systems with Minimal Availability, with Itai Ashlagi, working paper.
  • Appeared as an extended abstract in the 15th Conference on Web and Internet Economics (WINE 2019).

Mazel tov and tebrikler, Suleyman.

Welcome to the club.

Money and repugnance

 Readers of this blog are already familiar with the association between money and repugnance.  Check out this Saturday Morning Breakfast Cereal comic: "Are the best things in life free?"

"It'd be more accurate to say 'The Best Things in Life are Extremely Costly Plus You're Prohibited From Buying Them Directly With Money"

Is open science just for those with abundant resources?

 I applaud the movement towards open science, to make publications freely available, but I can generally pay the associated publication fees.  If publications free of paywalls become more important, will that work further enhance the benefits of working at wealthy universities?  Should we fund open science differently?

Here are some thoughts on that in Nature by Tony Ross-Hellauer  of the Open and Reproducible Research Group at Graz University of Technology and Know-Center in Austria.

Open science, done wrong, will compound inequities. Research-reform advocates must beware unintended consequences.  by Tony Ross-Hellauer

"Open science is a vague mix of ideals. Overall, advocates aim to increase transparency, accountability, equity and collaboration in knowledge production by increasing access to research results, articles, methods and tools. This means that data and protocols should be freely shared in high-quality repositories and research articles should be available without subscriptions or reading fees.

"Making all that happen is expensive. Wealthy institutions and regions can afford this better than can poorer ones. At my university, in a high-income nation, I know I am privileged. In a collaboration to introduce open science at Ukrainian universities (including those displaced by conflict post-2014), I’ve been privy to difficult conversations about how to pay publication fees that are three times a professor’s monthly salary, and how to meet data-sharing requirements to be eligible for funding when institutional support is lacking. 

...

"A particularly pressing issue is open access (OA) publication fees, in which the benefit of free readership is being offset by new barriers to authorship. To support OA publishing, journals commonly charge authors, and charges are rising as the practice expands. My group and others have found that article-processing charges are creating a two-tier system, in which richer research teams publish more OA articles in the most prestigious journals. "

More on the looming shortage of new antibiotics

 From Medpage Today:

Superbugs Are Getting Stronger— Our defenses are getting weaker  by David Thomas, MS, and Emily Wheeler 

"There are only 64 antibacterial therapeutics currently in clinical development. That's compared to 1,300 treatments in development for various cancers. Over one-third of antibacterial drug candidates target just two bacteria: Clostridioides difficile and Mycobacterium tuberculosis. That leaves only 44 drugs to target all other pathogenic bacteria.

"In other words, the antibacterial pipeline is grievously small. And it's shrinking compared to previous decades. In the last 35 years, just one antibacterial with a novel way to target bacteria has been approved. Comparatively, 18 new antibacterials with novel targets were approved by the FDA between 1940 and 1990.

"Meanwhile, superbugs continue to grow stronger. New research estimates they claimed 1.27 million lives in 2019 -- more than twice the estimated number of annual deaths just 5 years prior.

...

"Every time we use an antimicrobial, the target microbes have a chance to survive and become resistant. So, clinicians prescribe them only when needed. But this sound medical practice makes for poor economic incentives for private companies in a market system.

"Take the experience of the biotech firm Achaogen, which secured FDA approval in 2018 for its novel antibiotic plazomicin (Zemdri), after 15 years of development. The medication treats infections caused by one of the most challenging superbugs, carbapenem-resistant Enterobacteriaceae.

"While important for the overall armamentarium, such novel antimicrobials are used particularly sparingly to prevent dangerous pathogens from developing resistance to our strongest medications. As a result, clinicians hold novel antibiotics like plazomicin in reserve, using them judiciously to preserve effectiveness. That means companies like Achaogen don't sell large quantities of the drugs they develop -- or earn back the capital they invested in the research and development process.

"Achaogen filed for bankruptcy in 2019. In the 3 years since, several other small biotech companies that successfully cleared the clinical pipeline with FDA-approved antibacterials have seen a similar fate.

"The market conditions for antimicrobials are so discouraging that most large biopharmaceutical companies have pulled out of the sector entirely. Small companies discovered over 80% of the antibacterial therapeutics currently in clinical trials.

"These dynamics are causing investors to vacate the antimicrobial sector, too. Venture capital funding for biotech firms focusing on antibacterial research declined over the last decade, while other areas such as oncology rose 700%.

... 

"One solution is the bipartisan, bicameral Pioneering Antimicrobial Subscriptions To End Upsurging Resistance (PASTEUR) Act, which would change the current dose-based payment model for certain antimicrobials. Under PASTEUR, the government would offer developers of the most critically needed antimicrobials between $750 million and $3 billion up front in exchange for access to their medications once they hit the market.

...

"Another bill under consideration is the Developing an Innovative Strategy for Antimicrobial Resistant Microorganisms (DISARM) Act. The legislation would increase Medicare reimbursements for certain antimicrobials"

************

I don't know how I should feel about the fact that proposed legislation is named with clever acronyms (and I'm not sure that DISARM sends the right message...)

Transplant wait lists and patient finances

 Here's a disturbing commentary on how the regulation of transplant centers interacts with patient finances and the decision of who to put on transplant wait lists. The authors suggest extending to all organs the financial coverage that Medicare currently gives to kidney transplants.

Viewpoint March 31, 2022

Medical Need, Financial Resources, and Transplant Accessibility by Sharad I. Wadhwani, MD, MPH1; Jennifer C. Lai, MD, MBA1; Laura M. Gottlieb, MD, MPH  JAMA. Published online March 31, 2022. doi:10.1001/jama.2022.5283

"In the US, the need for lifesaving organ transplants exceeds the availability of transplantable organs, and in 2021, approximately 12 000 patients died or developed complications that precluded a transplant while awaiting an organ.1 Transplant centers are thus forced to ration these scarce resources. The first step for patients to receive an organ is for them to be placed on a national waiting list, ranked according to objective clinical criteria intended to reflect medical necessity. However, the listing system permits transplant centers to factor in patient financial resources in making this initial wait listing decision, which equates to withholding lifesaving medical therapy from those deemed to have insufficient financial resources. This approach contributes to inequities in transplant accessibility and outcomes.

...

"The OPTN policy specifically prohibits allocation to be based on race and ethnicity or socioeconomic status. Wait listing decisions (a prerequisite to allocation) are instead made based on a transplant candidacy evaluation, a process undertaken to assess transplant suitability. This includes an assessment of the patient’s insurance and financial security for expenses associated with the transplant surgery and lifelong posttransplant immunosuppression and enables transplant centers to circumvent the final rule mandate prohibiting allocation based on socioeconomic status. For instance, expenses for immunosuppression medications can exceed several thousand dollars a month; even insured patients can incur out-of-pocket, noncovered expenses that may exceed $1000 a month, including parking costs, missed work, and medication co-payments.2

"In theory, financial evaluations are included in listing determinations because low-socioeconomic status (measured by neighborhood socioeconomic deprivation and public insurance) has been associated with wait list mortality and posttransplant outcomes, and these outcomes are closely monitored for the approximately 250 US transplant centers.3 If transplant outcomes deviate from national benchmarks, the center risks losing accreditation and center of excellence designations, thus jeopardizing the ability of the center to offer transplants to other patients in need. The financial implications for a transplant center with poor outcomes are substantial: the average billed charges during the 30 days prior through the 180 days after a transplant range from an estimated $440 000 for a kidney transplant to an estimated $1.7 million for a heart transplant.4 Considering that in 2018, each US transplant program performed a median of 250 kidney transplants in adults, the financial implications of losing accreditation may motivate transplant centers to select transplant candidates most likely to survive until and after receiving a transplant. The system appears designed to disadvantage patients with inadequate financial resources thereby excluding them from the transplant waiting list."

...

"One strategy for improving insurance coverage could be to expand Medicare coverage to every individual requiring a transplant. Patients with end-stage kidney disease of all ages qualify for Medicare insurance in the US, and this coverage extends for the life of the transplant, thereby ensuring that patients continue to receive organ-preserving immunosuppression. A similar bill could extend Medicare coverage to any organ transplant recipient, starting when entered on the waiting list and continuing for the life of the transplant. This could help alleviate the potential risks that transplant centers may perceive around care adherence but would not comprehensively address all financial barriers to care. To ensure patients have adequate resources for long-term graft survival and patient health, changes to insurers’ incentives will need to be accompanied by other national, state, and local strategies to strengthen financial stability for families experiencing medical hardship.

"Solid organ transplantation is one of the greatest medical achievements of the 20th century and has transformed many terminal illnesses to treatable conditions. Yet almost 70 years after the first successful transplant surgery, this procedure remains out of reach for too many. As the nation continues to grapple with racism and classism, medicine must continue to identify and reform policies and procedures that contribute to health inequities. Withholding a transplant from those with inadequate insurance, limited financial resources, or both, is a tragic example of ongoing injustice."

Kidney Paired Donation Chains Initiated by Deceased Donors

 Starting kidney exchange chains with a deceased donor is a good idea whose time is coming.  

Wen Wang, Alan B. Leichtman, Michael A. Rees, Peter X.-K. Song, Valarie B. Ashby, Tempie Shearon, John D. Kalbfleisch,  Kidney Paired Donation Chains Initiated by Deceased Donors, Kidney International Reports, 2022, https://doi.org/10.1016/j.ekir.2022.03.023.

(https://www.sciencedirect.com/science/article/pii/S2468024922012438)

"Abstract:

• Introduction: Rather than generating one transplant by directly donating to a candidate on the waitlist, deceased donors (DD) could achieve additional transplants by donating to a candidate in a kidney paired donation (KPD) pool, thereby, initiating a chain that ends with a living donor (LD) donating to a candidate on the waitlist. We model outcomes arising from various strategies that allow DDs to initiate KPD chains. 

• Methods: We base simulations on actual 2016-2017 US DD and waitlist data and use simulated KPD pools to model DD initiated KPD chains. We also consider methods to assess and overcome the primary criticism of this approach, namely the potential to disadvantage Blood Type O waitlisted candidates. 

• Results: Compared to shorter DD initiated KPD chains, longer chains increase the number of KPD transplants by up to 5% and reduce the number of DDs allocated to the KPD pool by 25%. These strategies increase the overall number of Blood Type O transplants and make LDs available to candidates on the waitlist. Restricting allocation of Blood Type O DDs to require ending KPD chains with LD Blood Type O donations to the waitlist markedly reduces the number of KPD transplants achieved. 

• Conclusion: Allocating fewer than 3% of DD to initiate KPD chains could increase the number of kidney transplants by up to 290 annually. Such use of DDs allows additional transplantation of highly sensitized and Blood Type O KPD candidates. Collectively, patients of each blood type, including Blood Type O, would benefit from the proposed strategies."

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Earlier:

Monday, November 22, 2021

A naturally occurring deceased-donor-initiated kidney exchange chain, by Maghen and Veale

Sunday, August 23, 2020

More on Deceased donors as non‐directed donors in kidney exchange chains

Tuesday, August 7, 2018

Deceased donor chains: Market design language is entering transplantation

Monday, April 11, 2016

Using deceased donor kidneys to start living donor kidney exchange chains

Science Talent Search in the schools, after 100 years

 When I was in high school in the 1960's, I participated in a long-established student competition called the Science Talent Search, which in those days was sponsored by Westinghouse.  In subsequent years it was sponsored by Intel, and lately by Regeneron.  Winners of the competition were feted in Washington and received college scholarships, but it was a fun experience also for the many more of us who just got to spend time studying and building things that helped us appreciate science.

It turns out that that competition is 100 years old now. Here's a press release, and here's a searchable site of notable alumni, among whom are two winners of the Fields Medal, and fourteen Nobel prize winners, so far. The site doesn't identify which noted alumni won awards as students, but my guess is that for most of us participation itself was the prize.  And I wonder what can be learned about science and math education from these competitions. (My sense is that you can certainly learn something about American immigration, and about the growing participation of girls and women from the student participants and prizewinners, and the notable alums in each decade...)

Here are this year's student winners: Students Win $1.8 Million at Regeneron Science Talent Search 2022 for Exceptional Research on Neutron Star—Black Hole Systems, Narrowband Radar, and Ribosome Movement in Protein Translation

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Earlier:

Friday, March 19, 2021

Matching theorist wins high school science talent search

Tuesday, January 30, 2018

Science talent search finalists (and some alumni)

MIT reinstates standardized tests, to increase diversity

 Here's the MIT announcement:

We are reinstating our SAT/ACT requirement for future admissions cycles by Stu Schmill '86 in order to help us continue to build a diverse and talented MIT

"After careful consideration, we have decided to reinstate our SAT/ACT requirement for future admissions cycles. Our research shows standardized tests help us better assess the academic preparedness of all applicants, and also help us identify socioeconomically disadvantaged students who lack access to advanced coursework or other enrichment opportunities that would otherwise demonstrate their readiness for MIT. We believe a requirement is more equitable and transparent than a test-optional policy."

...

"not having SATs/ACT scores to consider tends to raise socioeconomic barriers to demonstrating readiness for our education,

"⁠04 Although our analysis is specific to MIT, our findings directionally align with a major study conducted by the University of California’s Standardized Testing Task Force, which found that including SAT/ACT scores predicted undergraduate performance better than grades alone, and also helped admissions officers identify well-prepared students from less-advantaged backgrounds. It is also consistent with independent research compiled by education researcher Susan Dynarski that shows standardized testing can be an effective way to identify talented disadvantaged students who would otherwise go unrecognized. Of course, there may be institutions for whom this research does not hold true, but the findings are very robust for MIT, and have been for many, many years.relative to having them, given these other inequalities"

National Living Donor Assistance Center (NLDAC) support for lost wages and dependent care

 NLDAC, the National Living Donor Assistance Center, is spreading the word on the new ways it can reimburse expenses incurred by living organ donors who meet a means test and have no other sources of support.  Here are two relevant pages from their recent brochure:

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Earlier post (in connection with which matching budget increases have since come through):

Sunday, September 27, 2020

Removing financial disincentives to living organ donation: HRSA publishes Final Rule

Matching refugees to homes: Oxford celebrates Alex Teytelboym's work with HIAS

Here's a timely short video from Oxford celebrating Alex Teytelboym's work with the venerable refugee resettlement organization HIAS. 

 

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Earlier:  

Monday, April 29, 2019

Refugee resettlement in the U.S., by HIAS, using matching technology

Two courses on matching and market design in Stanford's MS&E department, by Ashlagi and Saberi (first meeting is today)

Itai Ashlagi and  Amin Saberi are offering courses on matching theory and market design this quarter. First meetings are today, in the morning and in the afternoon:

MS&E 230: Market design for engineers

Itai Ashlagi  T-Thu 9:45-11:15

Course description:  Marketplaces use algorithms and sets of rules in order to allocate resources among self-interested agents, who often hold necessary information. This course will provide key principles in engineering a marketplace, to identify relation between the rules in the marketplace and market failures, and how to redesign them to achieve desirable outcomes.  The course provides foundations of resource allocation systems building on game theoretic analysis.  The course explores economic and algorithmic tools from matching, mechanism design, auction theory and information design. Cases of existing and future marketplaces will be discussed, including ride-sharing systems, school choice programs, online dating, online advertising and organ allocation.

Some applied questions include: How should we assign students to schools? How should we match doctors to residency programs? Shall we price roads and the impact of tolls? How should we allocate affordable housing and arrange waiting lists? How should we incentivize hospitals to collaborate on kidney exchanges? How should we allocate food to food banks? How should reduce organ discards?  How can we assist in migration?  Why is some marketplace decentralized (college admissions) and others are more controlled? How should platforms set incentives? What incentives and frictions arise in blockchains? 

 **********

MS&E 319: Matching Theory
Amin Saberi  T Th 01:30p-03:00p

The theory of matching with its roots in the work of mathematical giants like Euler and Kirchhoff has played a central and catalytic role in combinatorial optimization for decades. More recently, the growth of online marketplaces for allocating advertisements, rides, or other goods and services has led to new interest and progress in this area.  

The course starts with classic results characterizing matchings in bipartite and general graphs and explores connections with algebraic graph theory and discrete probability. Those results are complemented with models and algorithms developed for modern applications in market design, online advertising, and ride-sharing.

Topics include: 

Matching, determinant, and Pfaffian
Matching and polynomial identity testing
Isolating lemma and matrix inversion, matching in RNC

Combinatorial and polyhedral characterizations 
The assignment problem and its dual, primal-dual, and auction algorithms
Tutte’s theorem, Edmond’s LP, and the Blossom algorithm

The Gallai-Edmonds decomposition, Berge-Tutte formula, and applications in Nash bargaining

The stable marriage problem
Gale-Shapley theorem, incentive and fairness issues
LP characterization, counting stable matchings

Matching in dynamic environments
Online matching under various arrival models
Applications in ride-sharing and online advertising

 

Computation of matching  

Combinatorial vs continuous algorithms, near-linear time algorithms

Matchings in sub-linear time, streaming computational models

Sparsifiers and stochastic matching 

Counting matchings  
The Van der Waerden conjecture, Bregman-Minc’s inequality
Deterministic approximations, counting matchings in planar graphs
Markov chain Monte Carlo algorithms, sequential importance sampling
The Ising model, applications, and basic properties

***********

 

 

Pay for the last period of repeated game experiments with stationary probability of ending, by Chandrasekhar and Xandri

 Here's a recent paper by Arun Gautham Chandrasekhar & Juan Pablo Xandri on how to preserve stage-game payoffs in an experiment implementing a repeated game that ends with a fixed probability after each stage. They show that paying participants for all periods, which works for risk neutral players, isn't as robust as playing for the (randomly determined) last period only.

 A note on payments in the lab for infinite horizon dynamic games with discounting. Economic Theory (2022). https://doi.org/10.1007/s00199-021-01409-x

Abstract: "It is common for researchers studying infinite horizon dynamic games in a lab experiment to pay participants in a variety of ways, including but not limited to outcomes in all rounds or for a randomly chosen round. We argue that these payment schemes typically induce different preferences over outcomes than those of the target game, which in turn would typically implement different outcomes for a large class of solution concepts (e.g., subgame perfect equilibria, Markov equilibria, renegotiation-proof equilibria, rationalizability, and non-equilibrium behavior). For instance, paying subjects for all rounds generates strong incentives to behave differently in early periods as these returns are locked in. Relatedly, a compensation scheme that pays subjects for a randomly chosen round induces a time-dependent discounting function. Future periods are discounted more heavily than the discount rate in a way that can change the theoretical predictions both quantitatively and qualitatively. We rigorously characterize the mechanics of the problems induced by these payment methods, developing measures to describe the extent and shape of the distortions. Finally, we prove a uniqueness result: paying participants for the last (randomly occurring) round, is the unique scheme that robustly implements the predicted outcomes for any infinite horizon dynamic game with time separable utility, exponential discounting, and a payoff-invariant solution concept."

"Infinite horizon dynamic games are typically implemented in the lab using the random termination method and paying for all rounds or a random round. Typically, a participant plays a round of a game which then continues to the subsequent round with a given probability (Roth and Murnighan 1978). To incentivize behavior, the experimenter pays the participant as a function of the history of play. The central problem is that in the lab payments are made after the experiment and therefore not consumed between stages of the game (as they would be in the realm of the model). Experiments in the literature, following Murnighan and Roth (1983), usually pay subjects for all rounds. More recently Azrieli et al. (2018) systematically catalogue work in a collection of top journals and show that 56% pay for all rounds and 37.5% pay for one or several randomly chosen rounds.

"Paying for all rounds is only valid when agents are assumed to be risk neutral (Murnighan and Roth 1983). While a section of the literature is interested in worlds respecting risk-neutrality, paying individuals for all rounds was (and often is) standard even when the models being tested explicitly deviated from risk neutrality. This lead to a dissonance between the theoretical ambitions and experimental implementation of such work. Indeed, Azrieli et al. (2018) document that 48% of the papers they examine do not justify their payment scheme in the given experiment whatsoever/

...

"In Sect. 3, we introduce and study the scheme wherein individuals are paid for the last round in a random-termination dynamic game. It implements all such models.2 The reason why this works is due to the (standard) observation that when we have exponential discounting, myopia with respect to the future is isomorphic to random termination of the game with some probability.3 Further, we show that in fact last round payment is the unique payment scheme that implements the game robustly. What this means is that for a given environment, one can find some agent and some history where for some preference (e.g., small amounts of curvature in some cases) the scheme fails to implement the target game. That is, the preference ordering for the agent in that situation is muddled and does not reflect that within the target game.

"Next, in Sect. 4, we provide a rigorous analysis of two payment schemes used in the literature – either payment for a randomly chosen round or all rounds – and show how these may induce games different from the target game."

Guns (concealed carry) and marijuana (recreational): two US maps

 In both maps, brown is the color of permissiveness.  E.g. on the northern border, only Maine and Montana don't require permits/prescriptions for either guns or marijuana...

The gun map is from this Washington Post story: Nearly half the country requires no permit to carry a concealed weapon — and it’s a growing trend By Kim Bellware

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from https://mjbizdaily.com/map-of-us-marijuana-legalization-by-state/

Queuing for ridesharing and organ allocation

 Queues for ridesharing drivers at airports (where some trips are much better than others) lead to lots of rejected trips by those at the head of the line, while they wait for a good one.  This is of course something that also occurs in deceased donor waiting lists.

Here's a paper that tackles the ridesharing problem:

Randomized FIFO Mechanisms by Francisco Castro, Hongyao Ma, Hamid Nazerzadeh, Chiwei Yan

Abstract: "We study the matching of jobs to workers in a queue, e.g. a ridesharing platform dispatching drivers to pick up riders at an airport. Under FIFO dispatching, the heterogeneity in trip earnings incentivizes drivers to cherry-pick, increasing riders' waiting time for a match and resulting in a loss of efficiency and reliability. We first present the direct FIFO mechanism, which offers lower-earning trips to drivers further down the queue. The option to skip the rest of the line incentivizes drivers to accept all dispatches, but the mechanism would be considered unfair since drivers closer to the head of the queue may have lower priority for trips to certain destinations. To avoid the use of unfair dispatch rules, we introduce a family of randomized FIFO mechanisms, which send declined trips gradually down the queue in a randomized manner. We prove that a randomized FIFO mechanism achieves the first best throughput and the second best revenue in equilibrium. Extensive counterfactual simulations using data from the City of Chicago demonstrate substantial improvements of revenue and throughput, highlighting the effectiveness of using waiting times to align incentives and reduce the variability in driver earnings."

"Many ridesharing platforms now maintain virtual queues at airports for drivers who are waiting in  designated  areas,  and  dispatch  drivers  from  the  queue  in  a  first-in-first-out  (FIFO)  manner.4 This resolves the congestion issues and is also considered more fair by many since drivers who havewaited the longest in the queue are now the first in line to receive trip offers.  At major U.S. airports,however, a driver at the head of the queue will receive the next trip offer in a few seconds under FIFO dispatching, if she declines an offer from the platform (see Figure 12).  As we shall see, thislowered cost of cherry-picking substantially exacerbates existing problems on incentive alignment.

...

"During busy hours, instead of accepting an average trip, drivers who are close to the head of the queue are better off declining most trip offers and waiting for only the highest earning trips.  Riders, however, have finite patience, despite being willing to wait for some time for a match.  When each driver decline takes an average of 10 seconds, 2 minutes had passed after a trip with low or moderate earnings (e.g.  trips to downtown Chicago) was offered to and declined by the top 12 drivers in the queue.5 At this point, it is very likely that the rider cancels her trip request, not knowing when a driver will be assigned, if at all.

...

"To  achieve  optimal  throughput  and  revenue  without  the  use  of  an  unfair  dispatch  rule,  weintroduce a family ofrandomized FIFO mechanisms.  A randomized FIFO mechanism is specifiedby a set of “bins” in the queue (e.g., the top 10 positions, the 10th to 20th positions, and so on).Each trip request is first offered to a driver in the first bin uniformly at random.  After each decline, the mechanism then offers the trip to a random driver in the next bin.  By sending trips gradually down the queue in this randomized manner, the randomized FIFO mechanisms appropriately align incentives using waiting times,  achieving the first best throughput and second best net revenue: the option to skip the rest of the line incentivizes drivers further down the queue to accept trips with  lower  earnings;  randomizing  each  dispatch  among  a  small  group  of  drivers  increases  each individual driver’s waiting time for the next dispatch, thereby allowing the mechanism to prioritize drivers closer to the head of the queue for trips to every destination without creating incentives for excessive cherry-picking."

Scott Kominers on entrepreneurial market design (podcast)

 Scott Kominers is interviewed on the Things to Know podcast, about the arc of his career, and how it led him to market design, and crypto, NFTs, and beyond.

"Market design is a sort of wrapper around economics..."

 

Practical market design and public policy

 Market designers who want to influence practice have some things in common with makers of public policy. Here are some reflections, in Nature, by Chen Chien-jen, a distinguished epidemiologist who recently finished a term as Vice President of Taiwan.

Taiwan’s pandemic vice-president — from lab bench to public office and back. Successful policy and preparedness require more diverse evidence than researchers often encounter. by Chen Chien-jen

"The first lesson: scientific training teaches us to seek out all the variables that might affect a system. My work as a minister taught me to expand that list of variables far beyond what is typical. Budgets, laws, staffing levels and more enter the picture. So do values and priorities.

...

"The second lesson: science is never enough to bring about a thriving society. That takes trust, robust institutions and social cohesion. 

...

"The third lesson: infectious and toxic agents have impacts that last for decades, so long-range investments in scientific infrastructure pay off. But action must be quick.

...

"For treatments to be effective, patients must receive them, which depends on where they are offered, what patients have to pay and what makes them inconvenient and uncomfortable."

U.S. kidney transplant statistics for 2020

 Here's a recent report in the American Journal of Transplantation: 

OPTN/SRTR 2020 Annual Data Report: Kidney

K. L. Lentine,J. M. Smith,A. Hart,J. Miller,M. A. Skeans,L. Larkin,A Robinson,K. Gauntt,A. K. Israni,R. Hirose,J. J. Snyder First published: 10 March 2022 https://doi.org/10.1111/ajt.16982

Abstract: "The year 2020 presented significant challenges to the field of kidney transplantation. After increasing each year since 2015 and reaching the highest annual count to date in 2019, the total number of kidney trans- plants decreased slightly, to 23642, in 2020. The decrease in total kidney transplants was due to a decrease in living donor transplants; the number of deceased donor transplants rose in 2020. The number of patients waiting for a kidney transplant in the United States declined slightly in 2020, driven by a slight drop in the number of new candidates added in 2020 and an increase in patients removed from the waiting list owing to death-important patterns that correlated with the COVID-19 pandemic. The complexities of the pandemic were accompanied by other ongoing challenges. Nationwide, only about a quarter of waitlisted patients receive a deceased donor kidney transplant within 5 years, a proportion that varies dramatically by donation service area, from 14.8% to 73.0%. The nonutilization (discard) rate of recovered organs rose to its highest value, at 21.3%, despite a dramatic decline in the discard of organs from hepatitis C-positive donors. Nonutilization rates remain particularly high for Kidney Donor Profile Index ≥85% kidneys and kidneys from which a biopsy specimen was obtained. Due to pandemic-related disruption of living donation in spring 2020, the number of living donor transplants in 2020 declined below annual counts over the last decade. In this context, only a small proportion of the waiting list receives living donor transplants each year, and racial disparities in living donor transplant access persist. As both graft and patient survival continue to improve incrementally, the total number of living kidney transplant recipients with a functioning graft exceeded 250,000 in 2020. Pediatric transplant numbers seem to have been impacted by the COVID-19 pandemic. The total number of pediatric kidney transplants performed decreased to 715 in 2020, from a peak of 872 in 2009. Despite numerous efforts, living donor kidney transplant remains low among pediatric recipients, with continued racial disparities among recipients. Of concern, the rate of deceased donor transplant among pediatric waitlisted candidates continued to decrease, reaching its lowest point in 2020. While this may be partly explained by the COVID-19 pandemic, close attention to this trend is critically important. Congenital anomalies of the kidney and urinary tract remain the leading cause of kidney disease in the pediatric population. While most pediatric de- ceased donor recipients receive a kidney from a donor with KDPI less than 35%, most pediatric deceased donor recipients had four or more HLA mis- matches. Graft survival continues to improve, with superior survival for living donor recipients versus deceased donor recipients."

Transplant coordinators

 Those of us adjacent to kidney exchange know that transplant coordinators are heroes, and I'm reminded of that by some recent news stories.

This is one, from YNET, by Tamar Ashkenazi, who runs the Israeli transplant organization. Transplant coordinators are nurses, and these flew to the Ukraine-Polish border to help care for refugees in transit:

Meet Israeli organ transplant coordinators who rushed to aid Ukrainian refugees  b yDr. Tamar Ashkenazi

"Among the earliest delegations Israel sent to Ukraine was one consisting of a group of organ transplant coordinators, who refused to remain neutral in the wake of the horrors of war. 

********

And here are some stories about Charles Bearden, one of the first transplant coordinators in the U.S.:

Life-saving matchmaker By KEN BECK For the Grundy County Herald

"Bearden, the longest-practicing organ transplant coordinator in the U.S., has observed a world of changes in organ transplants since he began his career in the 1970s."

***********

Transplant coordinator Charles Bearden has placed nearly 3,000 organs  by KEN BECK news@wilsonpost.com

"Organ transplant coordinators typically work 24-hour shifts 15 days a month. If Bearden makes it to the end of 2022, he will have fulfilled that role 45 years."

*********

 And here's an old post containing a poem by Marisol Robles (one of the first kidney recipients in a global kidney exchange) about Susan Rees, the transplant coordinator for the Alliance for Paired Kidney Donation:

Thursday, November 3, 2016

La maga de riñones: The kidney conjurer (a poem about kidney exchange by Marisol Robles)

Economics in a war zone: Tymofiy Mylovanov interviewed by Scott Kominers

 What's the first thing an economist has to think about when his country is invaded?  Supply chains.

Scott Kominers interviews Tymofiy Mylovanov, via Twitter, at Bloomberg.

How a Ukrainian Economist Is Fighting the Russians. Since the bombs started to drop, Kyiv School of Economics President Tymofiy Mylovanov has been working on the nightmare logistics of humanitarian aid in a war zone. By Scott Duke Kominers

"For the past three weeks Tymofiy Mylovanov, president of the Kyiv School of Economics in Ukraine, has been witnessing the effects of Russia’s invasion of Ukraine firsthand -- working from within a war zone to bring desperately needed medical supplies to the country. Mylovanov, an economics professor and former minister of Economic Development, Trade and Agriculture for the Ukrainian government, is directing fundraising and other aid efforts from his base in Lviv in western Ukraine. 

...

"Mylovanov: If you want to get something done during war, it must be project-based. A lot of people are just completely lost. People have all kinds of ideas that the government has to do something, or someone else has to do something, and so they don’t do anything. You really have to focus on a specific project and the entire logistical supply project chain. We rely a lot on trust. And this trust was developed over the last eight years. I started working with Ukraine in 2014. I was at [the University of Pittsburgh] when the invasion of Crimea happened and I felt I had to get engaged with Ukraine. And I developed some expertise on how things work in extreme circumstances. So that helps me a little bit now. For example, we knew what to do with finances. In 2014, I raised $50,000, and a lot of academics were giving me checks of $1,000, $2,000 just to help Ukrainians in 2014. And none of it was wasted.

"We don’t need food or paper towels. What the army needs is munitions and people need medical supplies, specific medical supplies. Most people die from blood loss after a cluster bomb or after some kind of ballistic missile falls.  There may be 20 or 200 people wounded. It’s a little bit like when an airplane cabin loses pressure, the masks fall down — and what you need to do is to put the mask on yourself and then help others. So in this case, the mask analogy is a medical kit, which allows you to stop bleeding. So you really have to ensure that you are not bleeding, and then that people next to you are not bleeding.

"So you have to have a lot of these medical kits, and they usually cost 10 or 20 bucks. But now of course they cost 100 bucks because it’s surge pricing and no one can deliver. So we are trying to focus on this specifically. Civilian authorities need them and even railroads are asking for these medical kits because evacuation trains get shelled and people die without this specific kit. We will deliver them. We have connections, there’ll be no [extra overhead charges]. It doesn’t get stolen on the way. And [your donation] is also tax deductible in the U.S. So for $100, you’ll save a life and get your taxes back.

"So that’s what we are doing. But the first thing is to make sure we can pay [for supplies]. Because it’s wartime, there are capital controls and no one can make payments [in the usual way]. So you have to figure out how we’re going to pay. Then you need to figure out how you’re going to collect [fundraising] money. You need to figure out how to do crypto. So I am [talking to] European currency exchanges and charitable foundations and [universities] in the U.S. and Ukraine and the central bank of Ukraine and other banks and CEOs to ensure that the financial monitoring [for sanctions] doesn’t stop me because it’s all automatically blocking everything.

"And you need to get suppliers. In war, there are so many intermediaries and fees. So you have to establish a procurement department to figure out who is serious. Once you have suppliers, you have to figure out all the [wartime] export licenses,  all these government regulations. And of course things get stolen on the way. For example, one large, well-known American charity sends 95 pallets of medical supplies to Ukraine. When it arrives, it’s only two pallets because 93 of them got stolen somewhere. Not in Ukraine — either in Poland or even in New Jersey. So you have to watch for this. You actually have to put your own people in Warsaw or in New Jersey, in Israel, in Sweden, to check what has been loaded at every point so that it doesn’t get stolen. It’s a logistical nightmare. And when you finally get it to Ukraine, people are shooting at you at checkpoints.

...

"All the fundraising goes directly to logistics. I have a website at the university of the charitable foundation [Kyiv School of Economics Humanitarian Relief Fund], and there is a Twitter post at my account. If I get a hundred dollars on that charitable foundation, it goes towards medical kits and it’s likely going to save a life."

Surrogacy disrupted in Ukraine

Along with all the other stories of struggle and courage coming to us from the Russian invasion of Ukraine, are those about surrogates, surrogate agencies, and intended parents trying to complete the transaction by uniting parents with newborns.

The WSJ has the story:

Ukraine Is a World Leader in Surrogacy, but Babies Are Now Stranded in a War Zone By Isabel Coles

"In the basement beneath one apartment block in Kyiv, 19 newborns lie in plastic cots, their cries mingling with the blare of air-raid sirens warning of incoming Russian strikes.

"The war in Ukraine has prevented their biological parents, in Canada, Germany, France and elsewhere from claiming babies born via the country’s many surrogate mothers.

“The number is growing every day,” said Denys Herman, legal adviser to Ukraine’s largest surrogacy agency, BioTexCom. It works with 600 surrogate mothers, some of whom gave birth to the babies being kept there. They are currently in the care of Ukrainian nannies.

"As Russia ramps up a violent push to take strategic cities, the fate of hundreds of surrogate mothers carrying babies, and newborns, across the country is becoming increasingly perilous. Hundreds of expectant parents are struggling to reach them.

...

"Surrogacy is big business in the country. While commercial surrogacy is legal in the U.S., Ukraine is a more affordable option for many couples looking for surrogate mothers. The process costs $43,000 in Ukraine, compared with $130,000 in the U.S., according to a 2020 study conducted by Australia’s Monash University. That has helped turn Ukraine into the second-most popular international surrogacy destination after the U.S., according to the study."

Unraveling and reneging in the summer internship market

 There are some costs to unraveling of offer dates, and some of them are borne by the companies that make very early offers. The WSJ has the story:

Summer Interns Jilt Companies as Better Offers Come Along. Some young professionals in training are job-hopping between internships before they even start, frustrating companies and campus career advisers.  By Lindsay Ellis

"Many college students are juggling multiple summer internship offers as companies try to lock in entry-level talent. So fierce is this year’s competition, recruiters and career advisers said, that some students are reneging on summer stints they accepted back in the fall as recruiters barrage them with interview requests and richer offers. Companies and colleges say reneging is still rare, but it is becoming more pervasive in the current recruiting frenzy.

...

"Some 15% of students who had accepted a 2022 internship offer in November said they were still “actively searching” for another offer, according to a survey of more than 100 students by research and analytics company Veris Insights.

"Corporate recruiters, including at Liberty Mutual Insurance Co. and General Mills Inc. , said more students are backing out of internship offers this year. Liberty Mutual said it is reviewing pay benchmarks. Other employers and campus career offices said some companies have boosted intern pay for certain in-demand students. Still more employers are stepping up contact with students between the time they accept offers and when they start jobs to keep them engaged.

...

"Students used to feel sheepish about backing out of offers, but Elizabeth Diley, campus talent acquisition leader at General Mills, said she has observed less remorse. The cereal and food maker usually hires about 150 interns each year; now it plans to over-hire, betting that some percentage of interns will renege on offers before their summer jobs start, she said.

"Companies typically recruit summer interns early in the academic year to lock in potential talent. The problem this year with commitments made months ago is that the hot job market is generating lots of new offers that can lure students away."