Four international kidney exchange programs: 3 achieve substantial success

 Here's a paper reporting on the experience of four cross-border kidney exchange programs, whose experience teaches an important lesson.  In particular (see the figure below), one of  the programs is run by Spain, Italy and Portugal, whose  total population of approximately 118 million people is far larger than the combined population of the other three*, but manages to do less than 5% of the total cross-border exchanges, far fewer than any of the others.  Despite its size, the Spain-Italy-Portugal program only tries to match hard-to-match patient-donor pairs with other hard-to-match pairs, unlike the other three programs.

 International Kidney Paired Donation Programs: Evolution and Practices of 4 Large Collaborations
Klimentova, Xenia PhD1; Domínguez-Gil, Beatriz MD, PhD2; Viana, Ana PhD1,3; Manlove, David PhD4; Andersson, Tommy PhD5; Ashkenazi, Tamar RN, PhD6; Berlakovich, Gabriela MD7; Böhmig, Georg A. MD8; Burton, Jo RN, PGDip9; Coll, Elisabeth MD, PhD2; Dittmer, Ian FRACP9; Fiaschetti, Pamela MD10; Fronek, Jiri MD, PhD11; Hughes, Peter D. MBBS, PhD12,13; Ivo da Silva, Margarida MD14; Mor, Eytan MD15; Viklický, Ondřej MD, PhD16; Weinreich, Ilse Duus BMLS17; Ferrari, Paolo MD, FRACP18,19
Transplantation ():10.1097/TP.0000000000005602, December 24, 2025. | DOI: 10.1097/TP.0000000000005602

"Plain Language Summary: Kidney paired donation (KPD) programs are organized in various countries to facilitate the donation of kidneys from willing but incompatible donors by matching them with pairs in similar situations. These programs often struggle with an accumulation of difficult-to-match recipients and small pools of incompatible pairs. To address this, several international collaborations have emerged to expand the pool sizes and increase the number of transplants by “exchanging” donors’ kidneys across countries. We identified 4 established international KPD programs, each supported by protocols and agreements signed by the participating parties. Each program is presented separately, detailing its historical establishment, operational aspects, and statistics on pool characteristics and performance. Following this, we provide a comparative analysis of key aspects across the 4 programs. Each program has its unique context and specificities. Even though 3 of 4 collaborations started just before the COVID-19 pandemic, they have collectively facilitated >450 transplants. This underscores the importance of further developing these collaborations to share practices and experiences, and to facilitate more transplants, particularly for difficult-to-match recipients. Three of the 4 presented collaborations are either fully operated or led by European countries. This highlights the crucial role of ongoing international cooperation in the development of KPDs, in particular in Europe. By further promoting collaboration among countries, we can facilitate pan-European exchanges and improve access to live kidney transplants for patients in need.

 ...

"A fundamental difference between the programs is their collaboration model. STEP, ANZKX, and the Czech-Austrian-Israeli collaboration operate as “merged pool” model, where all participating pairs are combined for joint matching runs. For STEP and ANZKX, no other matching runs are conducted by partners at any level (hospital or national), whereas in the Czech-Austrian-Israeli collaboration, the Austrian and Israeli partners report performing local exchanges whenever compatible pairs are identified.
 

"In contrast, KEPSAT uses a “sequential pool” model, where national matches are attempted first, and only unmatched pairs are entered into the international pool. It is recognized that the last 2 strategy strategies may lead to a fragmented market, potentially limiting matches for highly sensitized patients, as easier-to-match pairs are removed beforehand."

 It's ironic that a program that appears to be intended primarily to help hard-to-match pairs is organized in a way that limits them in this way.

The paper concludes on an optimistic note (with which I fully agree):

"In conclusion, ongoing international cooperation is essential for advancing KPD programs globally. Expanding cross-border exchanges and improving access to kidney transplants can greatly benefit patients worldwide. Additional strategies, such as NDADs, desensitization protocols, and the inclusion of compatible pairs, can further enhance the effectiveness of both national and international programs. Oversight of these initiatives is crucial to safeguarding the welfare of both donors and recipients, as well as to maximizing the success rates of kidney transplants.
 

"Looking ahead, new initiatives, and projects, funded by international health organizations, such as the European Kidney Paired Exchange Programme project (https://www.hnbts.hu/euro-kep/project), funded by EU4Health and starting in November 2024, aim to expand global collaboration among KPD programs, building on and strengthening existing partnerships. This increased international cooperation is expected to create additional opportunities for patients in need of kidney transplants worldwide, making life-saving transplants accessible to more individuals regardless of their geographic location."

 ########

Earlier: Portuguese transplant docs noted the problem and argued for more global kidney exchange:

Tuesday, March 12, 2024 Kidney exchange between Portugal and Spain, and prospects for global kidney exchange

 ######### 

*Notes on population:

Spain: 49 million; Italy 59 million; Portugal 10 million ; KEPSAT total pop =  approx 118 million

 Australia 28 million; NZ 5 million: ANZKX total pop approx 33 million

Austria: 9 million, Czech Republic  11 million, Israel 10 million: AT-CZ-IL total 30 million

Sweden: 11 million; Norway:  6 million; Denmark 6 million; Finland  6 million: STEP total approx 29 mil

Debate on international surrogacy in Norway

 In Norway, where surrogacy is illegal, there is a debate about whether surrogacy conducted legally in other countries should also be criminalized for Norwegians.

The Norwegian Broadcasting Co. (NRK) has the story (with a little help from Google translate):

Familieminister mener surrogati skal kunne være straffbart The Minister of Family Affairs believes that surrogacy should be punishable by Chris Burke Marthe  and Ingrid Tinmannsvik

"The debate about surrogacy has created debate in Norway over several years. In 2022, surrogacy is illegal in Norway.

"Minister for Children and Families Kjersti Toppe (Sp) believes it should still be illegal to have children in this way.

...

"surrogacy in itself can be compared to human trafficking. A commercial industry where there is a great danger of exploiting vulnerable women. Shall we make children an item you can order and buy?"

...

"No one knows how many surrogate children come to Norway each year. But last year, 61 Norwegian fathers said that they became the father of a child in one of the countries it is most common to go to for surrogacy. It shows figures the Ministry of Foreign Affairs has obtained from the foreign service missions.

"About 10 years ago, the Storting passed an exemption which means that people who have children through surrogacy abroad cannot be punished.

"Tops voted against the law change and still disagrees.

...

"Anette Trettebergstuen (Labor Party), Minister of Culture and Gender Equality, reacts to Toppe's comparison of surrogacy and human trafficking.

...

"She believes a ban on punishment would not work in practice.

"- Should parents who bring a baby to the country be imprisoned? It will definitely be against the best interests of the child. And even if fines were imposed, many would probably think it was worth it", she says."

HT: Øivind Schøyen

Assortative mating plus efficient wealth management in Norway, by Fagereng, Guiso & Pistaferri

 Here's a recent NBER working paper that sheds some further light on how assortative mating leads to divergence in family wealth. (Apparently the spouse who managed pre-marital wealth better has more weight in managing the family finances...). Among other things we learn that Norwegian data on income and wealth is really good.

Assortative Mating and Wealth Inequality  by Andreas Fagereng, Luigi Guiso & Luigi Pistaferri, NBER WORKING PAPER 29903 DOI 10.3386/w29903, April 2022

We use population data on capital income and wealth holdings for Norway to measure asset positions and wealth returns before individuals marry and after the household is formed. These data allow us to establish a number of novel facts. First, individuals sort on personal wealth rather than parents' wealth. Assortative mating on own wealth dominates, and in fact renders assortative mating on parental wealth statistically insignificant. Second, people match also on their personal returns to wealth and assortative mating on returns is as strong as that on wealth. Third, post-marriage returns on family wealth are largely explained by the return of the spouse with the highest pre-marriage return. This suggests that family wealth is largely managed by the spouse with the highest potential to grow it. This is particularly true for households at the top of the wealth distribution at marriage. We use a simple analytical example to illustrate how assortative mating on wealth and returns and wealth management task allocation between spouses affect wealth inequality.

College as a Marriage Market, by Lars Kirkebøen, Edwin Leuven, Magne Mogstad

Here's a recent working paper about college and marriage in Norway:

College as a Marriage Market, by Lars Kirkebøen, Edwin Leuven, Magne Mogstad

Abstract: Recent descriptive work suggests the type of college education (field or institution) is an important but neglected pathway through which individuals sort into homogeneous marriages. These descriptive studies raise the question of why college graduates are so likely to marry someone within their own institution or field of study. One possible explanation is that individuals match on traits correlated with the choice of education, such as innate ability, tastes or family environment. Another possible explanation is that the choice of college education causally impacts whether and whom one marries, either because of search frictions or preferences for spousal education. The goal of this paper is to sort out these explanations and, by doing so, examine the role of colleges as marriage markets. Using data from Norway to address key identification and measurement challenges, we find that colleges are local marriage markets, mattering greatly for whom one marries, not because of the pre-determined traits of the admitted students but as a direct result of attending a particular institution at a given time.

 Here's a summary from the Becker-Friedman Institute:

College as a Marriage Market, by Larn Kirkebøen, Edwin Leuven, Magne Mogstad

"The context of the authors’ study is Norway’s postsecondary education system. The centralized admission process and the rich nationwide data allow them to observe not only people’s choice of college education (institution and field) and workplace, but also if and who they marry (or cohabit with), and to credibly study effects of college enrollment. The authors find the following:

"The type of postsecondary education is empirically important in explaining whom but not whether one marries. 

"Enrolling in a particular institution makes it much more likely to marry someone from that institution. These effects are especially large if individuals overlapped in college, are sizable even for those who studied a different field and are not driven by geography.

"Enrolling in a particular field increases the chances of marrying someone within the field but only insofar as the individuals attended the same institution. Enrolling in a field makes it no more likely to marry someone from other institutions with the same field. 

The effects of enrollment on educational homogamy (or marriage between people from similar backgrounds) and assortativity vary systematically across fields and institutions, and tend to larger in more selective and higher paying fields and institutions. 

Only a small part of the effect of enrollment on educational homogamy can be attributed to matches within the same workplace.

Lastly, the effects on the probability of marrying someone within their institution and field vary systematically with cohort-to-cohort variation in sex ratios within institutions and fields. This finding is at odds with the assumption in canonical matching models of large and frictionless marriage markets.

Taken together, these findings suggests that colleges are effectively local marriage markets, mattering greatly for the whom one marries, not because of the pre-determined traits of the students that are admitted but as a direct result of attending a particular institution at a given time."