Kidney exchange between Israel and the Czech Republic

 The Jerusalem Post reports another kidney exchange between Israel and the Czech Republic:

Miraculous kidney donation between friends spans continents and save lives. The complex and sensitive cross-continental operation required coordination between senior officials in both countries.   https://www.jpost.com/international/article-804396   By JERUSALEM POST STAFF  MAY 30, 2024 18:39

"it was soon discovered that Glaor was not a direct match for a transplant, and their medical details were entered into the National Transplant Center's cross-matching database. The entry resulted in an international kidney transplant exchange in which Glaor donated his kidney to a patient in the Czech Republic, and the wife of the Czech patient donated her kidney to Shitrit.

"The complex and sensitive cross-continental operation required coordination between senior officials in both countries, with an emphasis on the precise timing of operating rooms, flights, and quick security and customs arrangements.

"The operation began in the middle of the night at the Hadassah University Medical Center in Jerusalem’s Ein Kerem. It was managed and coordinated by the National Transplant Center.

"Dr. Tamar Ashkenazi, director of the National Transplant Center, was in charge of coordinating the transplant.  Alongside her on the flight to Prague were coolers containing two kidneys that were removed overnight from two Israeli donors at Hadassah Ein Kerem, which were intended for transplantation in two Czech patients. 

"In the evening, at around 10 p.m., the transplants in Israel were completed, and the Czech kidneys successfully functioned in the bodies of the Israeli recipients, as reported similarly from Prague regarding the Israeli kidneys that were transplanted in the Czech Republic.

""We planned the process precisely, and were in constant contact with our counterparts in the Czech Republic regarding the surgical issues. Every action that takes place is critical and impacts the continuation of the operation," said Dr. Ashraf Imam, a senior surgeon in the transplant unit at Hadassah, who participated in the transplant operation."

Kidney Exchange in Latin America and the Caribbean

 Kidney exchange isn't yet thriving in Latin America, but the basic infrastructure is in place. It would make a lot of sense to jumpstart kidney exchange by allowing cross border exchange, so that there would be a large enough pool of patient-donor pairs to make finding a match easy. Here's an article surveying the member countries of the Latin America and Caribbean Transplant Society.

Bastos, Juliana, David José de Barros Machado, Raquel Megale Moreira, Gustavo Fernandes Ferreira, and Elias David-Neto. "Kidney Paired Donation in Latin America and the Caribbean: An Update." Transplantation 108, no. 6 (2024): 1257-1258.

"we assess the situation of KPD in the countries affiliated with the Latin America and Caribbean Transplant Society (STALYC).

  

"Guatemala was the first country to publish a scientific report on KPD in 2018,8 with 4 kidney paired transplants performed between 2010 and 2017.

"Two reports from Argentina on local news websites reported 2-way exchanges involving 2 pairs in 20159 and 2018.10

"Costa Rica published a 2-way exchange on the hospital’s social media page in 2016,11 whereas a 2-way exchange transplantation was performed in Brazil in 2020.12

"Mexico is leading the reported KPD activity with a first experience involving 4 pairs in a chain beginning with an altruistic donor13 reported in 2019. A more recent publication reported on 22 pairs transplanted with longer chains and excellent results.14

"It is interesting to note that there are 6 countries—Panama, Ecuador, Venezuela, Peru, Chile, and Paraguay—with laws explicitly permitting KPD. Thus far, there has not been a report on KPD in those countries, which is likely due to the relatively recent publication of these legislations, all of which occurred after 2010.

...

"A recent publication has shed light on the potential of KPD in low-to-middle income countries (LMICs), strongly advocating for the promotion and encouragement of KPD programs, including considerations of cost advantages.17 Of additional relevance, valuable recommendations on initiating KPD programs in LMICs include starting with smaller chains, considering simultaneous surgeries, and implementing effective organ transport strategies.17 By adopting these strategies, LMICs can address compatibility issues and enhance their organ transplantation capabilities.

"Considering that KT is the superior and more cost-effective treatment option for patients with CKD, it is puzzling that the initiation of KPD programs remains limited in a region primarily composed of LMICs. Although some countries may have implemented KPD programs without publication, genuinely active programs beyond Mexico remain missing. It is crucial to emphasize that in most of these countries, deceased donor transplantation also falls significantly short of estimated needs.3,7 The entire infrastructure surrounding transplantation, including both living and deceased donors, continues to require substantial improvements. Particularly for KPD, initiatives such as educational campaigns for physicians, recipients, and donors, as well as investments in logistics and software in addition to a legal framework, need to be encouraged. Similar to KPD programs in Europe,5,18 collaborative efforts across countries could benefit smaller countries. Transplant societies, including STALYC, could play a vital role in supporting the advancement of paired donation, ensuring improved access to transplantation for their populations, especially with living donors."

The Path to a Match for Interventional Cardiology Fellowships

The Society for Cardiovascular Angiography & Interventions has started a fellowship match, and here's an article describing the familiar marketplace failure that led to that decision, involving unraveling of application, interview and appointment dates, with the resulting congestion and exploding offers, and the process of reaching sufficient consensus to move to a centralized match ( to be run by the NRMP).

The Path to a Match for Interventional Cardiology Fellowship: A Major SCAI Initiative  by Douglas E. Drachman MD, FSCAI (Chair) a, Tayo Addo MD b, Robert J. Applegate MD, MSCAI c, Robert C. Bartel MSc, CAE d, Anna E. Bortnick MD, PhD, MSc, FSCAI e, Francesca M. Dea d, Tarek Helmy MD, MSCAI f, Timothy D. Henry MD, MSCAI g, Adnan Khalif MD, FSCAI h, Ajay J. Kirtane MD, SM, FSCAI i, Michael Levy MD, MPH, FSCAI j, Michael J. Lim MD, MSCAI k, Ehtisham Mahmud MD, MSCAI l, Nino Mihatov MD, FSCAI m, Sahil A. Parikh MD, FSCAI i, Laura Porter CMP d, Abhiram Prasad MD n, Sunil V. Rao MD, FSCAI o, Louai Razzouk MD, MPH, FSCAI o, Samit Shah MD, PhD, FSCAI p, Adhir Shroff MD, MPH, FSCAI q, Jacqueline E. Tamis-Holland MD, FSCAI r, Poonam Velagapudi MD, FSCAI s, Fredrick G. Welt MD, FSCAI t, J. Dawn Abbott MD, FSCAI (Co-Chair), Journal of the Society for Cardiovascular Angiography & Interventions, in press.

"Abstract: The field of interventional cardiology (IC) has evolved dramatically over the past 40 years. Training and certification in IC have kept pace, with the development of accredited IC fellowship training programs, training statements, and subspecialty board certification. The application process, however, remained fragmented with lack of a universal process or time frame. In recent years, growing competition among training programs for the strongest candidates resulted in time-limited offers and high-pressure situations that disadvantaged candidates. A grassroots effort was recently undertaken by a Society for Cardiovascular Angiography & Interventions task force, to create equity in the system by establishing a national Match for IC fellowship. This manuscript explores the rationale, process, and implications of this endeavor."

"over the past several years program directors and candidates found that the process has devolved, with wide variation in application timelines and on-the-spot offers, which disadvantage candidates and programs looking to interview a range of applicants.

"The pressures and unfair features of the existing system were further fueled by the transition to virtual interviews related to the COVID-19 pandemic. With logistics of travel no longer a consideration, programs could commence interviews nearly immediately after the applications became available. This led to more candidates being interviewed in rapid succession, and a system evolved in which programs quickly assessed candidates, offered positions, and applied pressure for candidates to accept offers or be passed over for other candidates.

"In response to the shortcomings of the current system, members of Society for Cardiovascular Angiography & Interventions (SCAI) were inspired to lead a grassroots educational campaign to organize IC program directors and the broader interventional community to commit to a regulated “Match” process under the established National Resident Match Program (NRMP). This manuscript provides an account of how this process unfolded and how a Match for IC fellowship was ultimately created.

...

"From the applicant’s perspective, the lack of a structured timeline for the application process required candidates to make career decisions early in the first year of cardiovascular disease training and to compose their application materials 2 years in advance of starting IC training. With ERAS open to application submission in the fall of the second year for the December release to programs, fellows had limited time on clinical rotations to determine their interest and aptitude for IC. Additionally, letters of recommendation, written at this early stage, risked not being fully reflective of each candidate’s capacity to improve and develop the technical skills and clinical knowledge important for success in the field. There were other disadvantages to candidates in the existing system. Fellows at programs with an IC fellowship had an advantage of securing an internal spot but were often pressured to limit their exploration of the opportunities at other programs, potentially disadvantaging them in the long term.

"Another problem with the existing system was that the pressure to recruit candidates on a tight timeline limited the opportunity to interview applicants from a wide variety and diversity of programs, potentially reducing the ability to recruit underrepresented candidates from varied programs. Despite an overall increase in the diversity of physicians entering the workforce,11 there has been little change in the applicant pool for IC over the years, with fewer than 5% of applicants self-reporting as Black race or Hispanic ethnicity and only 10% identifying as women.12

"Competition among the programs, each vying for the seemingly strongest candidates, degenerated into a system that favored quick decision-making on the part of programs to offer positions as early as possible. The influence of the COVID-19 pandemic in 2020 and 2021 negatively impacted an already high-pressure application process, compounding its many weaknesses.13 Fellowship interviews were hosted virtually rather than in person, which enabled candidates to interview at a greater number of programs without the need to travel. In addition, the virtual format accelerated the tempo of an application process that was already felt to be too fast, resulting in an increase in so-called “exploding offers”—offers that required the accepted candidate to respond within a very short timeframe or risk losing the offer. This practice placed significant pressure on candidates to make quick decisions, often forcing them to determine whether to accept the offer from 1 institution before having the opportunity to participate in interviews with—let alone see and evaluate—other programs or fully understand the ramifications of accepting an offer on their personal lives. At the same time, the accelerated timetable left many programs scrambling to identify applicants, as the number of available candidates diminished rapidly due to applicants accepting time-sensitive, exploding offers.

...

"As with other national efforts of this magnitude, the path to develop consensus in favor of a Match was not without challenges. There were several program directors around the country who strongly opposed the institution of a Match. These were well-regarded academicians and clinician educators who expressed very sincere concerns about the impact on fellows in their programs. The members of the SCAI Match Task Force addressed as many concerns as possible, providing the information necessary for each program director to make the best decision for their institution. A minority of program directors remained opposed to the initiative or did not engage with Task Force members despite multiple attempts to be contacted.

"The Match campaign proved highly effective, and by November 2022, the 75% threshold of programs and positions to implement the Match was met

...

"As the sponsor of the Match, SCAI considered the pros and cons of the “All In Policy,” where registered programs must attempt to fill all ACGME positions at the program through the Match.15,16 SCAI opted out of the “All In Policy” to allow programs to have flexibility for unique situations that require commitment to a candidate outside of the Match. 

...

"As a result of the successful implementation of the Match in IC, the first Match cycle for incoming IC fellows will open in the summer of 2024. Individuals eligible to apply include cardiovascular disease fellows in their third or final year of training and graduates who have completed fellowship and are in clinical practice. This class will start IC training in July 2025"

Organs, tissues, and medical devices are regulated very differently

 Here's an article in JAMA by a Michigan doctor and his Congresswoman, on the lack of regulation for some substances of human origin.

Urgent Need for Regulatory Oversight of Human Cells, Tissues, and Cellular and Tissue–Based Products, by Robert P. Dickson, MD; Deborah A. Dingell, MS, JAMA. 2024;331(20):1703-1704. doi:10.1001/jama.2024.6834

" In 2021, an outbreak of M tuberculosis occurred in the US when contaminated bone graft material was implanted into 113 patients, 77% of whom developed clinically apparent tuberculosis.

...

[Again in 2023] "the Centers for Disease Control and Prevention (CDC) had identified additional tuberculosis-infected patients who had received implants of the same product, harvested from the same donor. At final count, 36 patients in 7 states had undergone implantation of bone graft tissue contaminated with M tuberculosis.

...

"Given the rigorous safety testing required of most medical therapies, how could 2 lethal outbreaks of tuberculosis occur in as many years, arising from the same product, distributed by the same company?

"The answer lies in the FDA’s designation of this product as a human cells, tissues, and cellular and tissue–based product (HCT/P) (Table). This class of therapies, which includes bone grafts, skin grafts, and stem cells, is not subject to the same regulatory standards as pharmaceuticals, biological products (such as blood products and monoclonal antibodies), or organ transplants. This designation has profound regulatory and clinical consequences

Sigecom Test of Time Award 2024 for AdWords and generalized online matching by Mehta, Saberi, Vazirani, and Vazirani

 The SIGecom Test of Time Award recognizes the author or authors of an influential paper or series of papers published between ten and twenty-five years ago that has significantly impacted research or applications exemplifying the interplay of economics and computation. More details and nomination procedure…

The Test of Time Award Winners for 2024 are Aranyak Mehta, Amin Saberi, Umesh Vazirani, and Vijay Vazirani  

They are cited for "introducing and solving a model of online matching with budgets that has seen many practical applications to online markets and broad and continuing impact in the literature."

in their paper

AdWords and generalized online matching, Journal of the ACM 54(5), 2007, Article 22

Abstract: How does a search engine company decide what ads to display with each query so as to maximize its revenue? This turns out to be a generalization of the online bipartite matching problem. We introduce the notion of a trade-off revealing LP and use it to derive an optimal algorithm achieving a competitive ratio of 1−1/e for this problem.

From the introduction:

"Internet search engine companies, such as Google, Yahoo and MSN, have revolutionized not only the use of the Internet by individuals but also the way businesses advertise to consumers. Typical search engine queries are short and reveal a great deal of information about user preferences. This gives search engine companies a unique opportunity to display highly targeted ads to the user.

"The online advertising mechanisms used by search engines, including Google’s AdWords, are essentially large auctions where businesses place bids for individual keywords, together with limits specifying their maximum daily budget. The search engine company earns revenue when it displays their ads in response to a relevant search query (if the user actually clicks on the ad). Indeed, most of the revenues of search engine companies are derived in this manner [Battelle 2005]. One factor in their dramatic success is that, unlike conventional advertising, search engine companies are able to cater to low-budget advertisers (who occupy the fat tail of the power law distribution governing advertising budgets of companies and organizations).

"The following computational problem, which we call the adwords problem, is a formalization of a question posed to us by M. Henzinger: There are (private communication, 2004). N bidders, each with a specified daily budget bi . Q is a set of query words. Each bidder i specifies a bid ciq for query word q ∈ Q. A sequence q1q2 · · · q M of query words q j ∈ Q arrive online during the day, and each query q j must be assigned to some bidder i (for a revenue of ciq j ). The objective is to maximize the total revenue at the end of the day while respecting the daily budgets of the bidders.

"In this article, we present a deterministic algorithm achieving a competitive ratio of 1 − 1/e for this problem, under the assumption that bids are small compared to budgets."

###########

Last year's award:

Monday, April 3, 2023

Test of Time Award 2023 to Immorlica & Mahdian, and Ashlagi, Kanoria & Leshno

#######

"Past and Present Members of the Test of Time Award Committee: Yeon-Koo Che, Yiling Chen, Nikhil Devanur, Joan Feigenbaum, Jason Hartline, Bobby Kleinberg, Paul Milgrom, Noam Nisan, Asu Ozdaglar, David Parkes, David Pennock, Alvin Roth, Tim Roughgarden, Larry Samuelson, Tuomas Sandholm, Yoav Shoham, Éva Tardos, Moshe Tennenholtz"

Marijuana policy and use in the U.S., 1979-2022, by Jonathan Caulkins, in Addiction

 Here's a paper forthcoming in the journal Addiction:

Changes in self-reported cannabis use in the United States from 1979 to 2022, by Jonathan P. Caulkins, published online 22 May 2024, https://doi.org/10.1111/add.16519 

"Abstract

Background and aims: Multiple countries are considering revising cannabis policies. This study aimed to measure long-term trends in cannabis use in the United States and compare them with alcohol use.

Design and setting: Secondary analysis of United States general population survey data.

Participants: The national surveys had a total of 1 641 041 participants across 27 surveys from 1979 to 2022.

Measurements: Rates of use reported to the US National Survey on Drug Use and Health and its predecessors are described, as are trends in days of use reported. Four milepost years are contrasted: 1979 (first available data and end of relatively liberal policies of the 1970s), 1992 (end of 12 years of conservative Reagan-Bush era policies), 2008 (last year before the Justice Department signaled explicit federal non-interference with state-level legalizations) and 2022 (most recent data available).

Findings: Reported cannabis use declined to a nadir in 1992, with partial recovery through 2008, and substantial increases since then, particularly for measures of more intensive use. Between 2008 and 2022, the per capita rate of reporting past-year use increased by 120%, and days of use reported per capita increased by 218% (in absolute terms from the annual equivalent of 2.3 to 8.1 billion days per year). From 1992 to 2022, there was a 15-fold increase in the per capita rate of reporting daily or near daily use. Whereas the 1992 survey recorded 10 times as many daily or near daily alcohol as cannabis users (8.9 vs. 0.9 M), the 2022 survey, for the first time, recorded more daily and near daily users of cannabis than alcohol (17.7 vs. 14.7 M). Far more people drink, but high-frequency drinking is less common. In 2022, the median drinker reported drinking on 4–5 days in the past month, versus 15–16 days in the past month for cannabis. In 2022, past-month cannabis consumers were almost four times as likely to report daily or near daily use (42.3% vs. 10.9%) and 7.4 times more likely to report daily use (28.2% vs. 3.8%).

Conclusions: Long-term trends in cannabis use in the United States parallel corresponding changes in cannabis policy, with declines during periods of greater restriction and growth during periods of policy liberalization. A growing share of cannabis consumers report daily or near daily use, and their numbers now exceed the number of daily and near daily drinkers."

Daily and Near Daily (DND) use

...

"That is still not as high as for cigarettes. The 2022 NSDUH survey finds that 58.7% of PM ["Past Month"] cigarette smokers smoked ‘daily’—defined as ‘smoked one or more packs of cigarettes per day’ [8]. Therefore, there are more daily cigarette smokers than DND PM marijuana users (24.1 vs 17.7 million). 3 Still, patterns of marijuana consumption have shifted from being like alcohol to being closer to cigarette use. It is also no longer a young person's drug. In 2022, people 35 and older accounted for (slightly) more days of use than did those under the age of 35."

Gonzalo Arrieta defends his dissertation

Gonzalo Arrieta defended his dissertation last week.

Here's his job market paper:

Procedural Decision-Making In The Face OfComplexity by Gonzalo Arrieta and Kirby Nielsen

Abstract: A large body of work documents that complexity affects individuals’ choices, but the literature has remained mostly agnostic about why. We provide direct evidence that individuals use different choice processes for complex and simple decisions. We hypothesize that individuals resort to “procedures”—cognitively simpler choice processes that we characterize as being easier to describe to another person—as the complexity of the decision environment increases. We test our hypothesis using two experiments, one with choices over lotteries and one with choices over charities. We exogenously vary the complexity of the decision environment and measure the describability of choice processes by how well another individual can replicate the decision-maker’s choices given the decision-maker’s description of how they chose. We find strong support for our hypothesis: Both of our experiments show that individuals’ choice processes are more describable in complex choice environments, which we interpret as evidence that decision-making becomes more procedural as complexity increases. We show that procedural decision-makers choose more consistently and exhibit fewer dominance violations, though we remain agnostic about the causal effect of procedures on decision quality. Additional secondary evidence suggests that procedural decision-making is a choice simplification that reduces the cognitive costs of decision-making."

##########

Another of his papers is a really creative investigation of human welfare:

What You Don't Know May Hurt You: A Revealed Preferences Approach by Gonzalo Arrieta and Lukas Bolte

Abstract: The dominant approach to welfare is based on revealed preferences and thus is restricted to settings where the individual knows their preferences have been fulfilled. We use a choosing-for-others framework to experimentally study welfare when what the individual believes to be true differs from what is actually true. About 42% of participants see welfare as independent of beliefs; 22% see welfare as only depending on beliefs; and 29% see a lower, but still positive, welfare effect when beliefs are fixed. Furthermore, the average participant values accurate beliefs. Our results suggest most people support the idea that welfare goes beyond awareness, which can inform media regulation, informational policies, and government communication.

 

Here's a figure from the instructions about the creation of "real" and "fake" inscribed copies of books. A third party judged the welfare to the recipient

"Our altruistically revealed preference paradigm consists of asking surrogate participants to trade off a monetary bonus given to the Receiver, and the Receiver getting the books with the original notes over those with the fake notes. The bonus amount is a surprise to the Receiver to minimize concerns that they use it to deduce which books they got (i.e., to maintain obliviousness). Our three requirements allow us to interpret the bonus amount that leaves participants indifferent between giving the original and fake notes as a measure of the change in the Receiver’s welfare. As a benchmark, we also elicit the welfare effect when the Receiver does learn which notes they get."

********

Welcome to the club, Gonzalo.

Matching for love or profit at Stanford

 Looking for a date, a marriage, a business partner?  Stanford might have the right app for you.

Here's the story from the Stanford Daily

Match, Marry, Capitalize? A catalog of Stanford’s matchmaking services, By Oriana Riley

"Here’s how matchmakers have attempted to help the Stanford community find love, friendships and business partners. 

Marriage Pact 

Perhaps the most famous Stanford matchmaking service, Marriage Pact, originated as a final project for a Stanford economics project. The annual service, which uses a survey to match compatible individuals for friendships and romantic relationships, has expanded to 88 campuses and more than 400,000 people.

...

"Founder Pact 

"Founder Pact presented an opportunity for students to try their hand not at love, but entrepreneurship. Founder Pact, created by the Business Association of Stanford Entrepreneurial Students (BASES), aimed to match entrepreneurs to realize their business ideas together. 

"The Founder Pact form, however, is now closed. 

"Wing

"A baby bird on the Stanford dating scene is Wing, announced to Stanford students via email on April 18. According to the email, Wing is built on the idea of “set[ting] up your friends.” 

Recent papers on matching: May GEB

 The May issue of Games and Economic Behavior has several papers on matching that caught my eye:

Games and Economic Behavior, Volume 145, May 2024

Strong core and Pareto-optimality in the multiple partners matching problem under lexicographic preference domains, by Péter Biró and Gergely Csáji

Abstract: We study strong core and Pareto-optimal solutions for multiple partners matching problem under lexicographic preference domains from a computational point of view. The restriction to the two-sided case is called stable many-to-many matching problem and the general one-sided case is called stable fixtures problem. We provide an example to show that the strong core can be empty even for many-to-many problems, and that deciding the non-emptiness of the strong core is NP-hard. On the positive side, we give efficient algorithms for finding a near feasible strong core solution and for finding a fractional matching in the strong core of fractional matchings. In contrast with the NP-hardness result for the stable fixtures problem, we show that finding a maximum size matching that is Pareto-optimal can be done efficiently for many-to-many problems. Finally, we show that for reverse-lexicographic preferences the strong core is always non-empty in the many-to-many case.

Bayesian stable states, by Yi-Chun Chen and Gaoji Hu 

Abstract: This paper extends the Bayesian stability notion of Liu (2020) to define the Bayesian stability of a market state, which consists of a matching outcome and an information structure. The information structure can be arbitrarily heterogeneous and can accommodate learning among agents. We first establish that a Bayesian stable matching function of Liu (2020) can be recast as Bayesian stable market states with homogeneous information. We then illustrate the usefulness of such an extension by (i) refining Liu's Bayesian efficiency notion to define the Bayesian efficiency of a market state and (ii) generalizing his result—that Bayesian stable matching functions are Bayesian efficient—to an analogous one for market states. More importantly, we show that (iii) a decentralized matching process converges to a Bayesian stable market state and thereby offer a decentralized foundation for Liu's Bayesian stable matching function.

Efficient matching under general constraints  by Kenzo Imamura, Yasushi Kawase

Abstract: We study indivisible goods allocation problems under constraints and provide algorithms to check whether a given matching is Pareto efficient. We first show that the serial dictatorship algorithm can be used to check Pareto efficiency if the constraints are matroid. To prove this, we develop a generalized top trading cycles algorithm. Moreover, we show that the matroid structure is necessary for obtaining all Pareto efficient matchings by the serial dictatorship algorithm. Second, we provide an extension of the serial dictatorship algorithm to check Pareto efficiency under general constraints. As an application of our results to prioritized allocations, we discuss Pareto improving the deferred acceptance algorithm.

Size is important in liver exchange

 Liver exchange has a lot in common with kidney exchange, in the sense that the issues involved in forming cycles and chains once you know which donors are compatible with which patients are very similar.  But a big difference is what constitutes a compatible donor: for livers, size (of the donor, and the donor liver) is very important, sensitively so.

Here's a paper forthcoming in the American Journal of Transplantation, by a team of transplant physicians and economists (with kidney exchange experience), on the importance of size.

"Enhanced Role of Multi-Pair Donor Swaps in Response to Size Incompatibility: The First Two 5-Way and the First 6-Way Liver Paired Exchanges" by Sezai Yilmaz, MD, FACS, Tayfun Sönmez, PhD, M. Utku Ünver, PhD, Volkan Ince, MD, Sami Akbulut, MD, PhD, FACS, Kemal Baris Sarici, MD, and Burak Isik, MD, American Journal of Transplantation, Brief communication, in press.

Abstract: A significant portion of liver transplantations in many countries is conducted via living-donor liver transplantation (LDLT). However, numerous potential donors are unable to donate to their intended recipients due to factors such as blood-type incompatibility or size incompatibility. Despite this, an incompatible donor for one recipient may still be a viable donor for another patient. In recent decades, several transplant centers have introduced liver paired exchange (LPE) programs, facilitating donor exchanges between patients and their incompatible donors, thereby enabling compatible transplants. Initially, LPE programs in Asia primarily involved ABO-i pairs, resulting in 2-way exchanges mainly between blood-type A and B recipients and donors. This practice has led to a modest 1-2% increase in LDLTs at some centers. Incorporating size incompatibility alongside blood-type incompatibility further enhances the efficacy and significance of multiple-pair LPEs. Launched in July 2022, a single-center LPE program established at Inönü University Liver Transplant Institute in Malatya, Türkiye, has conducted thirteen 2-way, nine 3-way, four 4-way, two 5-way, and one 6-way LPEs until February 2024. In 2023 alone, this program facilitated 64 LDLTs, constituting 27.7% of the total 231 LDLTs performed. This paper presents the world's first two 5-way LPEs and the first 6-way LPE.

*********

Another (not entirely unrelated) domain in which size is important, and exchange involves many pairs, involves the exchange of shells among hermit crabs. See these earlier posts (which included this short video):

xx

Saturday, July 21, 2012

Hermit Crab Vacancy Chains

Thursday, January 16, 2020

Vacancy chains and hermit crab housing, revisited

Tuesday, January 18, 2022

Evictions and coalitions in the housing market of hermit crabs--shell trafficking in the wild

NRMP Board of Directors (2020-2024), and a 40th anniversary

 This bit of glass marks the end of my term on the National Resident Matching Program (NRMP) Board of Directors.

One of the issues that consumed a lot of attention during my term is discussed in this post:

Friday, April 21, 2023

Transition from medical school to residency: defending the parts that work well (namely the NRMP Resident Match)

And here are all my posts about residents and fellows, going back to the beginning of this blog in 2008. (It's been interesting watching medical specialties begin to develop signaling in ways  reminiscent of signaling in the Economics job market, to deal with congestion of interviews and applications.*)

My first paper dealing explicitly with The Match suddenly seems to have been published 40 years ago:

Roth, A.E. "The Evolution of the Labor Market for Medical Interns and Residents: A Case Study in Game Theory", Journal of Political Economy, Vol. 92, 1984, 991‑1016. http://web.stanford.edu/~alroth/papers/evolut.pdf 

And the main report (with Elliott Peranson) of our redesign of The Match is now a quarter of a century old:

Roth, A.E. and E. Peranson, "The Redesign of the Matching Market for American Physicians: Some Engineering Aspects of Economic Design,” American Economic Review, 89, 4, September, 1999, 748-780. https://www.aeaweb.org/articles?id=10.1257/aer.89.4.748

*See yesterday's post for some discussion of market design interventions in job markets.

Social Media and Job Market Success: A Field Experiment on Twitter, by Qiu, Chen, Cohn, and Roth

 Here's a new working paper on SSRN:

Social Media and Job Market Success: A Field Experiment on Twitter, by Jingyi Qiu, Yan Chen, Alain Cohn, and Alvin E. Roth, May 20, 2024

"Abstract: We conducted a field experiment on Twitter to examine the impact of social media promotion on job market outcomes in economics. Half of the 519 job market papers tweeted from our research account were randomly assigned to be quote-tweeted by prominent economists. Papers assigned to be quote-tweeted received 442% more views and 303% more likes. Moreover, candidates in the treatment group received one additional flyout, with women receiving 0.9 more job offers. These findings suggest that social media promotion can improve the visibility and success of job market candidates, especially for underrepresented groups in economics such as women."

I gather that our paper has gone somewhat viral on twitter, with discussion about whether field experiments on job markets are ethical.  That's not a bad discussion to have, and of course we discussed that in the course of planning this experiment. (A similar discussion can and should be be had about any intervention in a market, not just an experiment.*)

Here is what we had to say about that in the paper.

"Despite the positive outcomes, one might question the ethics of our intervention, which randomly promotes a subset of JMPs on social media. However, we observe that senior economists naturally promote their own students and coauthors on Twitter. In comparison, we tweeted every JMP in our sample from our dedicated research account. Furthermore, while 80% of the influencers in our sample come from top 30 institutions, they quote-tweeted JMPs from a broader spectrum of academic institutions, thus allocating attention more equitably. Given that 92% of the JMCs in both the treatment and control groups accepted a job, it is unlikely that our treatment displaced those in the control group. The current focus on diversity, equity, and inclusion suggests that highlighting suitable candidates could potentially expand the number of job openings, making the job market for economists not entirely zero-sum. Lastly, the differential benefit of our treatment for women contributes to fostering a more inclusive economics profession. In summary, we argue that the knowledge gained from our experiment outweighs the potential cost."

*I've been involved in several operational (i.e. not experimental) interventions in job markets, including  the job market for new Econ Ph.D.s (e.g. signaling and the scramble):  see 

 Coles, Peter, John H. Cawley, Phillip B. Levine, Muriel Niederle, Alvin E. Roth, and John J. Siegfried, “The Job Market for New Economists: A Market Design Perspective,” Journal of Economic Perspectives, 24,4, Fall 2010, 187-206.  https://www.aeaweb.org/articles?id=10.1257/jep.24.4.187

Gaming the health care system; David Cutler's concerns

 The eminent Harvard health economist  David Cutler is worried by, among other things, the takeover of many healthcare facilities by private equity

Financial Games in Health Care—Doing Well Without Doing Good, by David M. Cutler, , JAMA Health Forum. 2024;5(5):e241591. doi:10.1001/jamahealthforum.2024.1591

"One form of gaming is asset looting—businesses taking money out of health care and then extorting state governments to replenish the funds. In an earlier publication,1 Song and I discussed how this works. Typically, a private equity firm owning a hospital sells the land the hospital is on and agrees to lease it back to the hospital at a high interest rate. The money from the sale is paid out to private equity investors; the hospital is saddled with the debt. If the hospital cannot repay the loan, the private equity firm threatens to close the facility unless the government covers the debt. Quality suffers during this process. Quality indicators at hospitals and nursing homes bought by private equity firms worsened after these changes in ownership.

...

"A third gaming strategy involves “coding intensity” and “upcoding,” which is coding and billing for more complex (and thus more expensive) care. These practices seek to maximize risk-adjusted reimbursements based on diagnostic codes. With coding intensity, the insurer codes all diagnoses ever received by an individual so that disease-based reimbursement is higher. Medicare pays private plans based on the health risks of their enrollees (measured by reported diagnoses). Thus, private insurers participating in Medicare Advantage spend enormous sums to find and code additional diagnoses. Estimates are that coding intensity will cost Medicare $50 billion in 2024.⁶

...

However, addressing coding practices is challenging because it may encourage risk selection. If payments for care provided to a patient are less than the costs incurred for that patient, insurers and clinicians may seek to treat only profitable patients and drive away the unprofitable ones. There are countless ways to do this. At the plan level, leaving prestigious hospitals out of a network and putting expensive medications in high cost-sharing tiers will drive away sicker patients.^9,10 Clinicians engage in risk selection as well. Widespread nonparticipation in Medicaid is evidence of the consequences when profitability varies with patient insurance status.

Because setting optimal health care reimbursement is difficult, less scrupulous clinicians and insurers will always have incentives to cut corners. Recently, it seems that the norms preventing this tendency are fraying. Thus, policymakers need to deter the idea that doing well can come at the expense of doing good. Whenever possible, malfeasance must be prevented in advance and punished when it occurs. Such a strategy will require willpower on the part of policymakers, not just tough words."

Britain's Infected Blood Inquiry Report: Prime Minister's apology, and the benefits and perils of hindsight

 After the publication  yesterday of Britain's Infected Blood Inquiry Report, the UK's Prime Minister apologized to the nation. Here's the BBC story:

PM apologises after infected blood scandal cover-up  By Nick Triggle and Jim Reed, BBC News

"Prime Minister Rishi Sunak says he is truly sorry for the failures over the infected blood scandal, calling it a decades-long moral failure.

"He was responding to the public inquiry's report into the scandal, which has seen 30,000 people infected from contaminated blood treatments.

"It found authorities covered up the scandal and exposed victims to unacceptable risks.

"Mr Sunak described it as a "day of shame for the British state".

...

""Today's report shows a decades-long moral failure at the heart of our national life. I want to make a wholehearted and unequivocal apology."

"He said the attitude of denial was hard to comprehend and was to "our eternal shame".

...

Labour leader Sir Keir Starmer apologised too, describing it as one of the "gravest injustices" the country had seen and saying victims had "suffered unspeakably".

***********

I've now had the opportunity to read some of the (2000 page) report, and it leaves me in two minds.  On the one hand, as summarized in various news stories about the report, it deals with a long history during which British clinicians could have responded faster to growing evidence about hepatitis and HIV in the blood supply, and the various British governing coalitions could certainly have acknowledged earlier and more fully that people had been infected.

On the other hand, some of the harms to people who were infected by blood-borne pathogens are clearer in hindsight than they were at the times that they began to occur.

The cases of hemophila patients (many of them children, many of them at Treloar's, a school for disabled children including many with severe hemophilia) are particularly jarring.  Many of those children are no longer living, having been infected with HIV in the  1980's, before it was positively identified as the cause of AIDS (but after there was evidence that something in the blood carried the infection). The clotting factors (extracted from plasma pooled from many donors) that were being explored to treat hemophilia patients, are  (today standard treatments for hemophilia, but in the period covered by the report they were subjects of research, and were, tragically, infected with HIV, and hepatitis C before it's virus had been identified.

Here's a passage (from Vol. 1, p23) of the report that crystallizes why I think it's easier to assess blame in hindsight than it was at the time: (NANBH stands for non-A non-B Hepatitis, as Hep C was still something of a mystery.)

"By 1978 there were a number of reports showing that NANBH was linked to persistent liver damage. Amongst them was a paper published in September 1978 in The Lancet, authored by Dr Eric Preston and colleagues in Sheffield. In his oral evidence to the Inquiry, Dr Mark Winter said that this paper “blew out of the water instantly the idea that this [NANB hepatitis] was nothing to worry about because their study showed, as did other studies, that most of these patients had very significant chronic liver disease”. He thought doctors had been unwilling to think that NANBH might be a problem, because factor concentrate had brought “such spectacular benefits”: it was this reluctance to face the facts described in scientific journals that had prevented earlier acceptance of the seriousness of the problem."

The report also dwells on the difficulties that the UK faced in becoming self-sufficient in non-commercial plasma and clotting factor from domestic sources.  But self sufficiency is a world-wide problem today in states that depend on unpaid domestic donors. So it's not clear how culpable the British blood services should be considered on that account.

And it's a complicated question, because some of the U.S. commercial suppliers started heat treating their plasma to effectively destroy many pathogens, before this became common in the U.K.

The report states (Vol 1, p49)

"Some clinicians were reluctant to embrace commercial heat-treated products. There was as yet little direct evidence of how reliable the claims about commercial heat-treated products were in practice. Although there was no evidence of side-effects after a year of use in the US, heat-treated commercial products were not licensed for use in the UK until early in 1985. It is not difficult to see why clinicians may have preferred to wait for domestic product rather than change their treatment practices. Further, commercial products were believed to be more likely to carry hepatitis than domestic ones. Understandable though this reluctance may have been, it did not excuse continued use of unheated products beyond a short period into 1985."

So, British physicians were caught between desire for domestic plasma (from unpaid donors, which they believed was safer), and reluctance to use U.S. commercial plasma as it became the safer alternative.  And British plasma processors waited until 1985 to start producing their own heat treated plasma products. The results were tragic, but (unlike some of the later delays and evasions that the report spells out) I don't see that there is in every instance a clear case of blame.

The chair of the Infected Blood Inquiry is Sir Brian Langstaff , "a former judge of the High Court of England and Wales."  Judges have experience at hearing evidence, and may have some professional inclination to explain events in terms of guilt.  Not that there isn't plenty to apologize for.

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Here are all my posts on blood plasma.

Britain's Infected Blood Inquiry Report published today

 The UK commissioned a report on infections in its blood supply in the 1970's and 80's, and on the government's belated responses during and afterwards, as some 3,000 people died from HIV and other infections.  It's a long and complicated report, which came out today, and is available at

Infected Blood Inquiry Report

I've started to read it, and hope have more to say in a few days.  (It condemns many past decisions about maintaining the blood supply, providing medical care, and then failing to acknowledge past harms, which the current report is particularly aimed at addressing.)

In the meantime, here are some news reports.

From the BBC:

NHS and government covered up infected blood scandal By Nick Triggle and Jim Reed, BBC News

From the NYT:

Report Finds ‘Catalog of Failures’ in U.K. Contaminated Blood Scandal - A six-year inquiry found that the deaths of about 3,000 people and the infection of tens of thousands of others could have mostly been avoided.  By Aurelien Breeden  May 20, 2024

The labor market for OnlyFans chatters

 Here's a story by a professional writer and journalist, who appears to be a middle-aged dad, about his efforts to find and then master a job impersonating a 20-something female sex performer chatting with her fans on the website OnlyFans.

Wired has the story:

.I Went Undercover as a Secret OnlyFans Chatter. It Wasn’t Pretty. Your online influencer girlfriend is actually a rotating cast of low-wage workers. I became one of them. by BRENDAN I. KOERNER

"Like many of OnlyFans’ top earners, she had hired a management agency to help keep up with her customers’ demands for personal attention. “The chat specialists they give you, that was a huge deal for me,” she said. The agency provided a team of contractors whose sole job is to masquerade as the creator while swapping DMs with her subscribers. These textual conversations are meant to be the main way that OnlyFans users can interact with the models they adore.

"The existence of professional OnlyFans chatters wouldn’t have surprised me so much if I’d given just a few moments’ thought to the mathematical realities of the platform. OnlyFans has thrived by promising its reported 190 million users that they can have direct access to an estimated 2.1 million creators. It’s impossible for even a modestly popular creator to cope with the avalanche of messages they receive each day. The $5.6 billion industry has solved this logistical conundrum by entrusting its chat duties to a hidden proletariat, a mass of freelancers who sustain the illusion that OnlyFans’ creators are always eager to engage—sexually and otherwise—with paying customers.

...

"Gradually I realized that my best shot at understanding how chatters operate would be to join their ranks. As an English major who’s been fortunate enough to make a living with words for more than 20 years, I naively assumed I was qualified to land a gig. And as a writer, I was curious to learn what kind of artistry the job would require—what it takes to ensure that OnlyFans users never doubt they’re really interacting with the objects of their desire.

"AS I EMBARKED on my job hunt, I asked the owner of a top-tier OnlyFans agency for tips on how to make myself an appealing candidate. He was pessimistic about my odds of getting hired, mainly because I’m American. He said agencies tend to favor contractors who reside in lower-wage countries. That insight was borne out as I poked around the online communities where chatters find help-wanted ads; though the vast majority of OnlyFans users live in the US, the bulk of my competitors were based in places like the Philippines and Venezuela. Judging by their posts on the r/OnlyFansChatter subreddit and in an invite-only Facebook group, these workers are relatively well-educated, with university-level English and ace typing skills that some developed in high-pressure call centers. They also put up with all manner of abuses: OnlyFans agencies are notorious for stiffing their freelancers, forcing them to work 70-hour weeks, and summarily firing them if they miss a shift due to a power outage."

IVF for sex selection: legal in the U.S

Slate has the story:

The Parents Who Want Daughters—and Daughters Only. Sex selection with IVF is banned in much of the world. Not in the U.S. by Emi Nietfeld

"Sex selection was once controversial in the U.S. and is banned in almost every other country. Many Americans unaware of the process still assume that it’s that way. In reality, it has now become a standard part of IVF here. For some, the option to sex select is a perk of an otherwise exacting process. For others, it’s the whole point of doing IVF in the first place.

...

"Still, “the very act of sex selection is sexist,” argues Arianne Shahvisi, a professor of philosophy at Brighton and Sussex Medical School in the U.K., where elective sex selection is illegal.

...

"It’s not just the U.K. Virtually all the industrialized world—including Canada, Australia, and every European country besides Cyprus—bans sex selection except in rare medical cases. Most nations prohibit the practice on the grounds that it promotes sexism and that the children born from it may be harmed by gendered expectations. Widespread preference for a certain sex can also skew the population—as in India and China, where abortion and infanticide of girls have resulted in tens of millions more men than women. 

...

"In 1994 the American Society for Reproductive Medicine, the nonprofit that provides the industry’s professional guidelines, condemned sex selection for nonmedical reasons. Yet with no enforcement power, the guidelines remained just that. Unlike in most peer nations, IVF in America is mostly privately paid and weakly regulated. Instead, market forces dominate. By 2018, despite the ASRM’s recommendation that they not offer sex selection, 75 percent of clinics continued to provide the service. Since then, the ASRM’s ethics committee has updated its position to a neutral stance."

Top Trading Cycles (TTC) is characterized by strategy proofness and individual rationality on a large set, by Özgün Ekici

 Here's a very nice result about TTC:

 Pair-efficient reallocation of indivisible objects, by Özgün Ekici, Theoretical Economics 19 (2024), 551–564

Abstract: We revisit the classical object reallocation problem under strict preferences. When attention is constrained to the set of Pareto-efficient rules, it is known that top trading cycles (TTC) is the only rule that is strategyproof and individually-rational. We relax this constraint and consider pair-efficiency. A rule is pair-efficient if it never induces an allocation at which a pair of agents gain from trading their assigned objects. Remarkably, even in the larger set of pair-efficient rules, we find that TTC is still the only rule that is strategyproof and individually-rational. Our characterization result gives strong support to the use of TTC in object reallocation problems.