Kidney Exchange to Overcome Financial Barriers to Kidney Transplantation.

Organ shortage is the major limitation to kidney transplantation in the developed world. Conversely, millions of patients in the developing world with end-stage renal disease die because they cannot afford renal replacement therapy-even when willing living kidney donors exist. This juxtaposition between countries with funds but no available kidneys and those with available kidneys but no funds prompts us to propose an exchange program using each nation's unique assets. Our proposal leverages the cost savings achieved through earlier transplantation over dialysis to fund the cost of kidney exchange between developed-world patient-donor pairs with immunological barriers and developing-world patient-donor pairs with financial barriers. By making developed-world health care available to impoverished patients in the developing world, we replace unethical transplant tourism with global kidney exchange-a modality equally benefitting rich and poor. We report the 1-year experience of an initial Filipino pair, whose recipient was transplanted in the United states with an American donor's kidney at no cost to him. The Filipino donor donated to an American in the United States through a kidney exchange chain. Follow-up care and medications in the Philippines were supported by funds from the United States. We show that the logistical obstacles in this approach, although considerable, are surmountable.

Incentivizing Authorization for Deceased Organ Donation With Organ Allocation Priority: The First 5 Years.

The allocation system of donor organs for transplantation may affect their scarcity. In 2008, Israel's Parliament passed the Organ Transplantation Law, which grants priority on waiting lists for transplants to candidates who are first-degree relatives of deceased organ donors or who previously registered as organ donors themselves. Several public campaigns have advertised the existence of the law since November 2010. We evaluated the effect of the law using all deceased donation requests made in Israel during the period 1998-2015. We use logistic regression to compare the authorization rates of the donors' next of kin in the periods before (1998-2010) and after (2011-2015) the public was made aware of the law. The authorization rate for donation in the period after awareness was substantially higher (55.1% vs. 45.0%, odds ratio [OR] 1.43, p = 0.0003) and reached an all-time high rate of 60.2% in 2015. This increase was mainly due to an increase in the authorization rate of next of kin of unregistered donors (51.1% vs. 42.2%). We also found that the likelihood of next-of-kin authorization for donation was approximately twice as high when the deceased relative was a registered donor rather than unregistered (89.4% vs. 44.6%, OR 14.27, p < 0.0001). We concluded that the priority law is associated with an increased authorization rate for organ donation.

Utilization of Deceased Donor Kidneys to Initiate Living Donor Chains.

We propose that some deceased donor (DD) kidneys be allocated to initiate nonsimultaneous extended altruistic donor chains of living donor (LD) kidney transplants to address, in part, the huge disparity between patients on the DD kidney waitlist and available donors. The use of DD kidneys for this purpose would benefit waitlisted candidates in that most patients enrolled in kidney paired donation (KPD) systems are also waitlisted for a DD kidney transplant, and receiving a kidney through the mechanism of KPD will decrease pressure on the DD pool. In addition, a LD kidney usually provides survival potential equal or superior to that of DD kidneys. If KPD chains that are initiated by a DD can end in a donation of an LD kidney to a candidate on the DD waitlist, the quality of the kidney allocated to a waitlisted patient is likely to be improved. We hypothesize that a pilot program would show a positive impact on patients of all ethnicities and blood types.

Historical Matching Strategies in Kidney Paired Donation: The 7-Year Evolution of a Web-Based Virtual Matching System.

Failure to convert computer-identified possible kidney paired donation (KPD) exchanges into transplants has prohibited KPD from reaching its full potential. This study analyzes the progress of exchanges in moving from "offers" to completed transplants. Offers were divided into individual segments called 1-way transplants in order to calculate success rates. From 2007 to 2014, the Alliance for Paired Donation performed 243 transplants, 31 in collaboration with other KPD registries and 194 independently. Sixty-one of 194 independent transplants (31.4%) occurred via cycles, while the remaining 133 (68.6%) resulted from nonsimultaneous extended altruistic donor (NEAD) chains. Thirteen of 35 (37.1%) NEAD chains with at least three NEAD segments accounted for 68% of chain transplants (8.6 tx/chain). The "offer" and 1-way success rates were 21.9 and 15.5%, respectively. Three reasons for failure were found that could be prospectively prevented by changes in protocol or software: positive laboratory crossmatch (28%), transplant center declined donor (17%) and pair transplanted outside APD (14%). Performing a root cause analysis on failures in moving from offer to transplant has allowed the APD to improve protocols and software. These changes have improved the success rate and the number of transplants performed per year.

Call to develop a standard acquisition charge model for kidney paired donation.

We propose a Medicare Demonstration Project to develop a standard acquisition charge for kidney paired donation. A new payment strategy is required because Medicare and commercial insurance companies may not directly pay living donor costs intended to lead to transplantation of a beneficiary of a different insurance provider. Until the 1970s, when organ procurement organizations were empowered to serve as financial intermediaries to pay the upfront recovery expenses for deceased donor kidneys before knowing the identity of the recipient, there existed similar limitations in the recovery and placement of deceased donor organs. Analogous to the recovery of deceased donor kidneys, kidney paired donation requires the evaluation of living donors before identifying their recipient. Tissue typing, crossmatching and transportation of living donors or their kidneys represent additional financial barriers. Finally, the administrative expenses of the organizations that identify and coordinate kidney paired donation transplantation require reimbursement akin to that necessary for organ procurement organizations. To expand access to kidney paired donation for more patients, we propose a model to reimburse paired donation expenses analogous to the proven strategy used for over 30 years to pay for deceased donor solid organ transplantation in America.

Nonsimultaneous chains and dominos in kidney- paired donation-revisited.

Since 2008, kidney exchange in America has grown in part from the incorporation of nondirected donors in transplant chains rather than simple exchanges. It is controversial whether these chains should be performed simultaneously 'domino-paired donation', (DPD) or nonsimultaneously 'nonsimultaneous extended altruistic donor, chains (NEAD). NEAD chains create 'bridge donors' whose incompatible recipients receive kidneys before the bridge donor donates, and so risk reneging by bridge donors, but offer the opportunity to create more transplants by overcoming logistical barriers inherent in simultaneous chains. Gentry et al. simulated whether DPD or NEAD chains would produce more transplants when chain segment length was limited to three transplants, and reported that DPD performed at least as well as NEAD chains. As this finding contrasts with the experience of several groups involved in kidney-paired donation, we performed simulations that allowed for longer chain segments and used actual patient data from the Alliance for Paired Donation. When chain segments of 4-6 transplants are allowed in the simulations, NEAD chains produce more transplants than DPD. Our simulations showed not only more transplants as chain length increased, but also that NEAD chains produced more transplants for highly sensitized and blood type O recipients.

Kidneys for sale: who disapproves, and why?

The shortage of transplant kidneys has spurred debate about legalizing monetary payments to donors to increase the number of available kidneys. However, buying and selling organs faces widespread disapproval. We survey a representative sample of Americans to assess disapproval for several forms of kidney market, and to understand why individuals disapprove by identifying factors that predict disapproval, including disapproval of markets for other body parts, dislike of increased scope for markets and distrust of markets generally. Our results suggest that while the public is potentially receptive to compensating kidney donors, among those who oppose it, general disapproval toward certain kinds of transactions is at least as important as concern about specific policy details. Between 51% and 63% of respondents approve of the various potential kidney markets we investigate, and between 42% and 58% want such markets to be legal. A total of 38% of respondents disapprove of at least one market. Respondents who distrust markets generally are not more disapproving of kidney markets; however we find significant correlations between kidney market disapproval and attitudes reflecting disapproval toward certain transactions-including both other body markets and market encroachment into traditionally nonmarket exchanges, such as food preparation.

Outcomes in Bariatric and Metabolic Surgery: an Updated 5-Year Review.

PURPOSE OF REVIEW: Knowledge regarding postoperative outcomes after bariatric and metabolic surgery continues to evolve. This review highlights key findings in outcomes research over the last 5 years related to weight loss, remission of obesity-related disease, reflux, revisional surgery, robotic-assisted surgical platforms, and adolescent populations. RECENT FINDINGS: Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) produce similar weight loss patterns at 5 years, while duodenal switch (BPD/DS) and related procedures are associated with maximal weight loss overall and optimal resolution of obesity-related comorbidities. Remission of type 2 diabetes mellitus (T2DM) following surgery is more likely in patients who are not insulin dependent prior to surgery. Bariatric and metabolic surgery offers a significant protective effect against coronary artery disease (CAD) and associated interventions in both diabetic and nondiabetic patients, as well as heart failure (HF). Gastroesophageal reflux disease (GERD) and dysphagia following SG are common, and routine endoscopic surveillance for Barrett's esophagus may be of significant utility. Robotic-assisted laparoscopic platforms concur similar outcomes to laparoscopic intervention, with a potential benefit in high BMI patients. Revisional surgery is most commonly performed for weight regain and/or inadequate weight loss following an index procedure, or reflux, and generally characterized by higher postoperative complication rates and longer inpatient lengths of stay (LOS). Surgical intervention in adolescent populations has similar weight loss and postoperative complication profiles to those seen in adult populations, with improved outcomes related to T2DM. Bariatric and metabolic surgery continues to evolve as a treatment for obesity and obesity-related comorbidities. While effective for weight loss and remission of obesity-related disease, SG is associated with high rates of postoperative GERD.

Toward a theory of bargaining: an experimental study in economics.

Contemporary economic theories of bargaining depend on aspects of the bargainers' preferences that are difficult to observe. This makes these theories difficult to test in natural environments. It has proved possible, however, to design experiments to test these theories in a controlled, laboratory environment. The results of these experiments reveal shortcomings and incompleteness in the descriptive power of currently available theories of bargaining. However, these results also suggest important regularities in bargaining behavior. Together with recent theoretical developments, these results suggest some directions in which a more descriptively powerful theory of bargaining might be developed.

New physicians: a natural experiment in market organization.

The National Resident Matching Program is a centralized clearinghouse through which new medical graduates in the United States obtain their first positions. The history of this market, from the market failures that the centralized system was designed to address, to the present, is discussed, and a hypothesis about the behavior of such markets is presented. New evidence is then presented from a set of similar centralized markets in the United Kingdom. Because some of these latter markets have failed, while others have succeeded, they provide a natural experiment that permits the hypothesis to be tested. The new evidence also suggests directions in which modifications of existing procedures might be considered.

Beneficial non-targeted effects of BCG--ethical implications for the coming introduction of new TB vaccines.

Non-targeted effect of BCG: Several recent studies suggest that BCG has beneficial non-targeted effects on general child survival in low-income countries. Studies of the effect of BCG on morbidity in humans are scarce; some found a positive effect of BCG and others show no effect. Non-targeted effects of vaccines-possible bias and confounding: The major argument against comparing vaccinated and unvaccinated groups is that there is a beneficial social selection bias for vaccinated children-the "Healthy vaccinee effect". However, controlling for various social and health-related background factors in the survival analyses had no effect on the estimates, making this source of bias less likely. A more powerful argument that the findings are not due to the healthy vaccinee effect is that differential non-targeted effects of other vaccines have been observed; diphteria-tetanus-pertussiss vaccination has marked negative effects on child survival, whereas measles vaccine has a positive effect in several studies. Several studies have shown better survival for children reacting to their BCG vaccination with a BCG scar or tuberculin skin test reaction (TST). It could be argued that the reacting children were immunologically stronger and therefore more likely to survive-the "Healthy reactor effect". However, recent findings show that a BCG scar and a TST reaction depend to a large extent on the vaccination technique. Hence, the BCG responses may reflect a true vaccine effect and not merely the health status of the children. Since HIV-1 has been shown to suppress both TST and BCG scar reaction in response to BCG, it is an obvious contributor to the healthy reactor effect, but excluding deaths of children with HIV-1 infection from analysis did not affect the beneficial effect of having a positive TST. Excluding children exposed to tuberculosis (TB) in the household did not affect the estimates either. Furthermore, there are strong sex-differential effects of BCG in both mortality and morbidity data, BCG being more beneficial for girls. These observations cannot consistently be explained by the healthy vaccinee or healthy reactor effects. Ethical implications: For future TB-vaccine studies, these findings imply that: These recommendations might be considered to delay or to be a too large obstacle for the development and trials of new TB vaccines. However, most of the non-targeted beneficial effects of BCG have been observed in children below 2 years of age, which is not a long follow-up time in a TB-vaccine trial. Furthermore, considering the difficulty in setting the TB diagnose in children and the lack of reliable TB-protection markers, it does not seem unreasonable to argue for monitoring of general morbidity and survival in future TB-vaccine trials.

A natural experiment in the organization of entry-level labor markets: regional markets for new physicians and surgeons in the United Kingdom.

The histories of seven regional markets for new physicians and surgeons in the United Kingdom are considered. Like the American market, these markets have experienced failures that led to the adoption of centralized market mechanisms. Because different regions employ different centralized mechanisms, these markets provide a test of the hypothesis that the success of the American market is related to the fact that it produces matches which are stable in the sense that no two agents mutually prefer to be matched to one another than to their assigned partners. Even in the more complex U.K. markets, this kind of stability plays an important role. Centralized markets that produced unstable matches in environments in which agents could act upon instabilities fared no better than the decentralized markets they replaced.

Structure and coarsening at the surface of a dry three-dimensional aqueous foam.

We utilize total-internal reflection to isolate the two-dimensional surface foam formed at the planar boundary of a three-dimensional sample. The resulting images of surface Plateau borders are consistent with Plateau's laws for a truly two-dimensional foam. Samples are allowed to coarsen into a self-similar scaling state where statistical distributions appear independent of time, except for an overall scale factor. There we find that statistical measures of side number distributions, size-topology correlations, and bubble shapes are all very similar to those for two-dimensional foams. However, the size number distribution is slightly broader, and the shapes are slightly more elongated. A more obvious difference is that T2 processes now include the creation of surface bubbles, due to rearrangement in the bulk, and von Neumann's law is dramatically violated for individual bubbles. But nevertheless, our most striking finding is that von Neumann's law appears to holds on average, namely, the average rate of area change for surface bubbles appears to be proportional to the number of sides minus six, but with individual bubbles showing a wide distribution of deviations from this average behavior.

Bubble statistics and coarsening dynamics for quasi-two-dimensional foams with increasing liquid content.

We report on the statistics of bubble size, topology, and shape and on their role in the coarsening dynamics for foams consisting of bubbles compressed between two parallel plates. The design of the sample cell permits control of the liquid content, through a constant pressure condition set by the height of the foam above a liquid reservoir. We find that in the scaling regime, all bubble distributions are independent not only of time, but also of liquid content. For coarsening, the average rate decreases with liquid content due to the blocking of gas diffusion by Plateau borders inflated with liquid; we achieve a factor of 4 reduction from the dry limit. By observing the growth rate of individual bubbles, we find that von Neumann's law becomes progressively violated with increasing wetness and decreasing bubble size. We successfully model this behavior by explicitly incorporating the border-blocking effect into the von Neumann argument. Two dimensionless bubble shape parameters naturally arise, one of which is primarily responsible for the violation of von Neumann's law for foams that are not perfectly dry.

Coarsening of a two-dimensional foam on a dome.

In this paper we report on bubble growth rates and on the statistics of bubble topology for the coarsening of a dry foam contained in the narrow gap between two hemispheres. By contrast with coarsening in flat space, where six-sided bubbles neither grow nor shrink, we observe that six-sided bubbles grow with time at a rate that depends on their size. This result agrees with the modification to von Neumann's law predicted by J. E. Avron and D. Levine [Phys. Rev. Lett. 69, 208 (1992)]. For bubbles with a different number of sides, except possibly seven, there is too much noise in the growth rate data to demonstrate a difference with coarsening in flat space. In terms of the statistics of bubble topology, we find fewer three-, four-, and five-sided bubbles, and more bubbles with six or more sides, in comparison with the stationary distribution for coarsening in flat space. We also find good general agreement with the Aboav-Weaire law for the average number of sides of the neighbors of an n-sided bubble.

Abrasion of flat rotating shapes.

We report on the erosion of flat linoleum "pebbles" under steady rotation in a slurry of abrasive grit. To quantify shape as a function of time, we develop a general method in which the pebble is photographed from multiple angles with respect to the grid of pixels with a digital camera. This reduces digitization noise and allows the local curvature of the contour to be computed with a controllable degree of uncertainty. Several shape descriptors are then employed to follow the evolution of different initial shapes toward a circle, where abrasion halts. The results are in good quantitative agreement with a simple model, where we propose that points along the contour move radially inward in proportion to the product of the radius and the derivative of radius with respect to angle.