A novel two-stage network data envelopment analysis model for kidney allocation problem under medical and logistical uncertainty: a real case study.

Organ transplantation is one of the most complicated and challenging treatments in healthcare systems. Despite the significant medical advancements, many patients die while waiting for organ transplants because of the noticeable differences between organ supply and demand. In the organ transplantation supply chain, organ allocation is the most significant decision during the organ transplantation procedure, and kidney is the most widely transplanted organ. This research presents a novel method for assessing the efficiency and ranking of qualified organ-patient pairs as decision-making units (DMUs) for kidney allocation problem in the existence of COVID-19 pandemic and uncertain medical and logistical data. To achieve this goal, two-stage network data envelopment analysis (DEA) and credibility-based chance constraint programming (CCP) are utilized to develop a novel two-stage fuzzy network data envelopment analysis (TSFNDEA) method. The main benefits of the developed method can be summarized as follows: considering internal structures in kidney allocation system, investigating both medical and logistical aspects of the problem, the capability of expanding to other network structures, and unique efficiency decomposition under uncertainty. Moreover, in order to evaluate the validity and applicability of the proposed approach, a validation algorithm utilizing a real case study and different confidence levels is used. Finally, the numerical results indicate that the developed approach outperforms the existing kidney allocation system.

Implications of the Composite Allocation Score System for Lung Transplantation in the United States: Review of the New System.

Due to criticism regarding undue adherence to fixed geographic boundaries, the Lung Allocation Score system was recently replaced by the more holistic allocation via continuous distribution (CD). This review highlights the historical evolution of US lung allocation paradigms, outlines rationale for CD under the Composite Allocation Score system and discusses expected implications of this new system.

Crossing national borders for transplantation: A focused evaluation of deceased donor lung exports from the United States.

Organ transplantation is a life-saving treatment for end-stage organ failure patients, but the United States (US) faces a shortage of available organs. US policies incentivize identifying recipients for all recovered organs. Technological advancements have extended donor organ viability, creating new opportunities for long-distance transport and international sharing. We aimed to assess organ exports from deceased US donors to candidates abroad, a component of allocation policy allowed without suitable domestic candidates. Based on the national Scientific Registry of Transplant Recipients data from January 2014 to September 2023, 388 342 organs were recovered for transplantation, with 511 (0.13%) exported. Most exported organs were lungs (80%). Exported lung donors were older (41 vs 34 years, P < .001), more likely hepatitis C positive (22% vs 4%, P < .001), and more likely donors after circulatory death (20% vs 7%, P < .001). Lungs that were eventually exported were offered to more US potential transplant recipients (median = 65) than those kept in the US (median = 21 and 41 for lungs recovered by nonexporting and exporting organ procurement organizations, respectively; P < .001). Our study highlights the necessity for further research and clear policy initiatives to balance the benefits of cross-border sharing while considering potential opportunities for more aggressive organ allocation within the US.

Introduction of the donor centre virtual crossmatch in Eurotransplant.

On 24 January 2023, Eurotransplant has introduced the virtual crossmatch for kidney and pancreas allocation as a better alternative for the physical Complement Dependent Cytotoxicity (CDC) crossmatches at the donor centre, which were associated with a longer cold ischaemia time and false positive reactions. For the time being, the physical CDC crossmatch at the recipient centre will remain in place as the final histocompatibility check. While Eurotransplant is certainly not the first organ allocation organisation to introduce virtual crossmatching, several novel aspects have been introduced, such as calculation of the virtual panel reactive antibody (vPRA) on 11 loci at the second-field level in addition to the serological broad and split level, electronic HLA typing data transmission using Histoimmunogenetics Markup Language (HML) file format, and the actual virtual crossmatch based on ambiguous, second-field HLA typing of the donor on all 11 loci. This short communication will focus on these novel aspects of the virtual crossmatch in Eurotransplant.

Impact of removing OPTN region from vascularized composite allograft allocation.

On 6/18/2020, the Organ Procurement and Transplantation Network (OPTN) implemented new policy replacing OPTN region with a 500 nautical mile (NM) circle around the donor hospital for the purpose of vascularized composite allograft (VCA) allocation. We used OPTN data to assess deceased donor VCA transplants in the 3 years pre- (6/19/2017-6/17/2020) vs. post-implementation (6/18/2020-6/17/2023). A total of 19 deceased donor VCA transplants were performed pre-policy (10 uterus, 3 bilateral upper limb, 1 unilateral upper limb, 3 face, 1 abdominal wall and 1 penis), and 11 post-policy (4 uterus, 1 bilateral upper limb, 2 face, 1 trachea, 2 abdominal wall, and 1 bilateral upper limb and face). Median distance from donor hospital to transplant hospital increased from 70 NM (range: 0-524 NM) pre-policy to 119 NM (range: 0-464 NM) post-policy. The majority of transplants in both policy eras were within 500 NM of the donor hospital [89.5% (N = 17/19) vs. 100% (N = 11/11)] and most remained within the same OPTN region as the donor hospital [68.4% (N = 13/19) vs. 90.9% (N = 10/11)]. Although it is difficult to draw strong conclusions about the policy's impact due to the low transplant volume and timing of implementation relative to the COVID-19 pandemic, data in the 3 years post-implementation suggest that 500 NM circles were a reasonable replacement for OPTN region in VCA allocation. The OPTN will continue to review data to monitor the policy's impact and inform future changes to VCA allocation, such as the transition to continuous distribution, a points-based framework expected to replace the current framework.

The Equitable Benefit Approach to guide the assessment of medical and psychosocial factors in liver transplant candidacy.

Lack of available organs poses a significant challenge in meeting the needs of patients with life-threatening liver disease who could benefit from liver transplantation (LT). Psychosocial vulnerability markers have been linked to post-transplant outcomes, raising questions about their use in patient selection. However, their incorporation into selection criteria raises concerns about health equity and potential discrimination. As a result, there is a pressing need to refine fair allocation systems that consider both clinical and psychosocial factors to ensure equitable access and optimize post-transplant outcomes. The Equitable Benefit Approach (EBA) proposed in this paper by the multidisciplinary group of clinical experts in LT from the Italian Society for the Study of the Liver seeks to address these concerns. It presents four procedural principles, the two allocative principles usually applied in transplantation (urgency and utility) and introduces a new one, the principle of health equity. The EBA aims to prioritize patients with the highest transplant benefit while addressing health inequalities. It emphasizes evidence-based decision-making and standardized assessment tools to reliably evaluate psychosocial risk factors. Implementing the EBA involves a multi-step process, including stakeholder engagement, prospective studies to validate its efficacy, development of institutional policies and algorithms, and ongoing monitoring and revision. By following these steps, health care providers can ensure that LT allocation decisions are transparent and responsive to evolving clinical and social contexts. Ultimately, the EBA should offer a comprehensive framework for fair patient selection in LT, considering both biomedical and psychosocial aspects.

Kidney transplant candidates' perspectives on the implementation of a Canadian Willingness to Cross program: A strategy to increase access to kidney transplantation for highly sensitized patients.

BACKGROUND: Kidney transplantation is the optimal treatment for end-stage renal disease. However, highly sensitized patients (HSPs) have reduced access to transplantation, leading to increased morbidity and mortality on the waiting list. The Canadian Willingness to Cross (WTC) program proposes allowing transplantation across preformed donor specific antibodies (DSA) determined to be at a low risk of rejection under the adaptive design framework. This study collected patients' perspectives on the development of this program. METHODS: Forty-one individual interviews were conducted with kidney transplant candidates from three Canadian transplant centers in 2022. The interviews were digitally recorded and transcribed for subsequent analyses. RESULTS: Despite limited familiarity with the adaptive design, participants demonstrated trust in the researchers. They perceived the WTC program as a pathway for HSPs to access transplantation while mitigating transplant-related risks. HSPs saw the WTC program as a source of hope and an opportunity to leave dialysis, despite acknowledging inherent uncertainties. Some non-HSPs expressed concerns about fairness, anticipating increased waiting times and potential compromise in kidney graft longevity due to higher rejection risks. Participants recommended essential strategies for implementing the WTC program, including organizing informational meetings and highlighting the necessity for psychosocial support. CONCLUSION: The WTC program emerges as a promising strategy to enhance HSPs' access to kidney transplantation. While HSPs perceived this program as a source of hope, non-HSPs voiced concerns about distributive justice issues. These results will help develop a WTC program that is ethically sound for transplant candidates.

Effect of the opioid crisis on the liver transplantation donor pool: A national analysis.

BACKGROUND: Over the last decade there has been a surge in overdose deaths due to the opioid crisis. We sought to characterize the temporal change in overdose donor (OD) use in liver transplantation (LT), as well as associated post-LT outcomes, relative to the COVID-19 era. METHODS: LT candidates and donors listed between January 2016 and September 2022 were identified from the Scientific Registry of Transplant Recipients database. Trends in LT donors and changes related to OD were assessed pre- versus post-COVID-19 (February 2020). RESULTS: Between 2016 and 2022, most counties in the United States experienced an increase in overdose-related deaths (n = 1284, 92.3%) with many counties (n = 458, 32.9%) having more than a doubling in drug overdose deaths. Concurrently, there was an 11.2% increase in overall donors, including a 41.7% increase in the number of donors who died from drug overdose. In pre-COVID-19 overdose was the 4th top mechanism of donor death, while in the post-COVID-19 era, overdose was the 2nd most common cause of donor death. OD was younger (OD: 35 yrs, IQR 29-43 vs. non-OD: 43 yrs, IQR 31-56), had lower body mass index (≥35 kg/cm2, OD: 31.2% vs. non-OD: 33.5%), and was more likely to be HCV+ (OD: 28.9% vs. non-OD: 5.4%) with lower total bilirubin (≥1.1 mg/dL, OD: 12.9% vs. non-OD: 20.1%) (all p < .001). Receipt of an OD was not associated with worse graft survival (HR .94, 95% CI .88-1.01, p = .09). CONCLUSIONS: Opioid deaths markedly increased following the COVID-19 pandemic, substantially altering the LT donor pool in the United States.

OPTN/SRTR 2022 Annual Data Report: Lung.

For the first time since the COVID-19 pandemic, the annual number of lung transplants performed in the United States increased. The year 2022, encompassed in this report, marks the last full calendar year where the Lung Allocation Score was used for ranking transplant candidates based on their estimated transplant benefit and donor lung allocation in the United States. In March 2023, a major change in transplant allocation policy occurred with the implementation of the Composite Allocation Score. Transplant rates have increased over the past decade, although there is variability among age, diagnosis, racial and ethnic, and blood groups. Over half of candidates received a lung transplant within 3 months of placement on the waiting list, with nearly 75% of candidates accessing transplant by 1 year. Pretransplant mortality rates remained stable, with approximately 13% of lung transplant candidates dying or being removed from the waiting list within a year of listing. Posttransplant survival remained stable; however, variability exists by age, diagnosis, and racial and ethnic groups.

Do Infectious Diseases After Kidney Retransplantation Differ From Those After First Kidney Transplantation?

Background: Infectious diseases (IDs) are highly relevant after solid organ transplantation in terms of morbidity and mortality, being among the most common causes of death. Patients undergoing kidney retransplantation (re-K-Tx) have been already receiving immunosuppressive therapy over a prolonged period, potentially facilitating subsequent infections. Comparing ID events after re-K-Tx and first kidney transplantation (f-K-Tx) can delineate patterns and risks of ID events associated with prolonged immunosuppression. Methods: We included adult patients with records on f-K-Tx and re-K-Tx in the Swiss Transplant Cohort Study. We analyzed ID events after f-K-Tx and re-K-Tx within the same patients and compared infection rates, causative pathogens, and infection sites. Recurrent time-to-event analyses were performed for comparison of infection rates. Results: A total of 59 patients with a median age of 47 years (range, 18-73) were included. Overall, 312 ID events in 52 patients occurred. In multivariable recurrent event modeling, the rate of ID events was significantly lower after re-K-Tx (hazard ratio, 0.70; P = .02). More bacterial (68.9% vs 60.4%) and fungal (4.0% vs 1.1%) infections were observed after f-K-Tx but fewer viral infections (27.0% vs 38.5%) as compared with re-K-Tx (P = .11). After f-K-Tx, urinary and gastrointestinal tract infections were more frequent; after re-K-Tx, respiratory tract and surgical site infections were more frequent (P < .001). Conclusions: ID events were less frequent after re-K-Tx. Affected sites differed significantly after f-K-Tx vs re-K-Tx.

Smart match: revolutionizing organ allocation through artificial intelligence.

In this transformative era of organ transplantation, integrating Smart Match and artificial intelligence (AI) emerges as a pivotal advancement, revolutionizing organ allocation processes. Smart Match employs AI algorithms, enhancing organ matching precision and optimizing transplantation outcomes. Leveraging machine learning addresses complexities in donor-recipient pairing, immunosuppression management, and post-operative care, promising to minimize waitlist mortality and improve patient wellbeing. The multifaceted potential of Smart Match lies in its ability to not only streamline current practices but also pave the way for future innovations in solid organ transplantation. As technology continues to evolve, the collaboration between Smart Match and AI exemplifies a beacon of progress, promising increased efficiency, equitable organ distribution, and improved patient care. This article delves into the paradigm shift facilitated by Smart Match and AI, emphasizing their transformative impact on the landscape of organ allocation and patient outcomes.

Impact of the Kidney Allocation Revision on Access to Kidney Transplantation and Outcomes in the United States.

BACKGROUND: The 2014 Kidney Allocation System (KAS) revision aimed to enhance equity in organ allocation and improve patient outcomes. This study assesses the impacts of the KAS revision on renal transplantation demographics and outcomes in the United States. METHODS: We conducted a retrospective study utilizing the Organ Procurement and Transplantation Network/Scientific Registry of Transplant Recipients (OPTN/SRTR) database from 1998 to 2022. We compared recipient and donor characteristics, and outcomes (graft failure and recipient survival) pre- and post-KAS revision. RESULTS: Post-KAS, recipients were significantly older (53 vs 48, P < .001) with an increase in Medicaid beneficiaries (7.3% vs 5.5%, P < .001). Despite increased graft survival, HR = .91 (95% CI 0.80-.92, P < .001), overall recipient survival decreased, HR = 1.06 (95% CI 1.04-1.09, P < .001). KAS revision led to greater racial diversity among recipients and donors, enhancing equity in organ allocation. However, disparities persist in graft failure rates and recipient survival across racial groups. DISCUSSION: The 2014 Kidney Allocation System revision has led to important changes in the renal transplantation landscape. While progress has been made towards increasing racial equity in organ allocation, further refinements are needed to address ongoing disparities. Recognizing the changing patient profiles and socio-economic factors will be crucial in shaping future policy modifications.

Evaluation of a delayed liver transplantation strategy for patients with HCC receiving bridging therapy: the DELTA-HCC study.

BACKGROUND & AIMS: To maximize utility and prevent premature liver transplantation (LT), a delayed LT strategy (DS) was adopted in France in 2015 in patients listed for any single HCC treated with resection or thermal ablation during the waiting phase. The DS involves postponing LT until recurrence. The purpose of this study was to evaluate the DS to make sure that it did not hamper pre- and post-LT outcomes. METHODS: Patients listed for HCC in France between 2015 and 2018 were studied. After data extraction from the national LT database, 2,025 patients were identified and classified according to six groups: single tumor entering DS, single tumor not entering DS, multiple tumors, no curative treatment, untreatable HCC or T1 tumors. Kaplan-Meier estimates of the 18-month risk of dropout for death, too sick to be transplanted or tumor progression before LT, 5-year post-LT HCC recurrence and post-LT survival rates were compared. RESULTS: Median waiting-time in the DS group was 910 days. Pre-LT dropout probability was significantly lower in the DS group compared to other groups (13% vs. 19%, p = 0.0043) and significantly higher in the T1 group (25.4%, p = 0.05). Post-LT HCC recurrence rate in the multiple nodules group was significantly higher (19.6%, p = 0.019), while 5-year post-LT survival did not differ among groups and was 74% in the DS group (p = 0.22). CONCLUSION: The DELTA-HCC study shows that DS does not negatively impact either pre- nor post-LT patient outcomes, and has the potential to allow for redistribution of organs to patients in more urgent need of LT. It can reasonably be proposed and pursued. The unexpectedly high risk of dropout in T1 patients seems related to the MELD-based offering rules underserving this subgroup. IMPACTS AND IMPLICATIONS: To maximize utility and prevent premature liver transplantation (LT), a delayed LT strategy was adopted in France in 2015. It involves postponing LT until recurrence in patients listed for any single HCC curatively treated by surgical resection or thermal ablation. The DELTA-HCC study was conducted to evaluate this nationwide strategy. It shows in a European LT program that delayed strategy does not negatively impact pre- nor post-LT patient outcomes and is relevant to up to 20% of LT candidates; thus, it could potentially enable the redistribution of organs to patients in more urgent need of LT. Such a delayed strategy can reasonably be pursued and extended to other LT programs. Of note, an unexpectedly high risk of dropout in T1 patients, seemingly related to MELD-based offering rules which underserve these patients, calls for further scrutinization and revision of allocation rules in this subgroup.

Impact of removing donation service area and region from pancreas allocation.

On March 15, 2021, the Organ Procurement and Transplantation Network (OPTN) replaced donation service area (DSA) and OPTN region as units of pancreas (PA) allocation with a 250 nautical mile (NM) circle with proximity points. We analyzed OPTN data for kidney-pancreas (KP) and PA candidates, transplants, and donors in the 2 years pre-policy (March 16, 2019, to March 14, 2021) and post-policy (March 15, 2021, to March 14, 2023). As expected, more transplants occurred at hospitals outside the recovering organ procurement organization's DSA post-policy (KP: 32.1% vs 57.3%, P < .001; PA: 61.6% vs 69.3%, P = .09), but the majority stayed within 250 NM (KP: 79.7% vs 85.0%, P < .001; PA: 55.4% vs 61.5%, P = .19). Median preservation time increased from 9.5 to 10.3 hours for KP (P < .001); there was little change for PA (8.5 vs 8.6 hours; P = .99). There were no statistically significant differences in 1-year posttransplant patient mortality or graft failure after implementation for KP (mortality: 3.6% vs 3.2%, P = .60; kidney graft failure: 4.9% vs 5.0%, P = .95; PA graft failure: 9.5% vs 8.9%, P = .65) or PA (mortality: 1.7% vs 2.2%, P = .72; PA graft failure: 12.2% vs 12.6%, P = .88). The removal of DSA and OPTN region from PA allocation has resulted in broader distribution with minimal impact on preservation time or posttransplant outcomes.

Sarcopenia in cirrhotic patients: Does frailty matter while waiting for a liver transplant?

Sarcopenia reflects patient frailty and should be routinely assessed due to its high prevalence in cirrhotic patients awaiting liver transplants. Pre-transplant nutritional optimization should be tailored for patients with a definitive diagnosis of sarcopenia, therefore improving functional status at transplant and reducing post-transplant mortality. Hepatologists and transplant surgeons should have raised awareness regarding sarcopenia and the reflected frailty that hinder posttransplant outcomes. The policymakers should also take into account when modifying the organ allocation model that sarcopenia or frailty might become a decisive factor in allocating organs for cirrhotic patients, in order to ensure post-transplant survival and quality of life.

The impact of high volumes of COVID-related lung transplant on waitlist mortality for non-COVID candidates in the United States.

Some patients with coronavirus disease 19 (COVID) develop serious, irreversible lung disease, including acute respiratory distress syndrome or pulmonary fibrosis. For select candidates, lung transplant is the only option to improve quality and length of life. Because of the severity of end-stage COVID-related lung disease, these candidates receive high allocation priority in the United States, including higher priority than many patients without COVID-related lung disease. This study assessed whether transplant centers with a large volume of COVID-related lung transplants experienced an increase in waitlist mortality for non-COVID transplant candidates. Nineteen centers were included as high-volume programs, defined as being in the top third of centers who transplanted COVID patients. Of the 2867 non-COVID patients waitlisted at these centers, there was no significant difference in waitlist mortalities of non-COVID transplant candidates between the pre-COVID transplant era (January 2018-February 2020) and during the period of high COVID transplant volume (March 2020-October 2022) (subhazard ratio: .92 [95% CI = .81-1.05], p = .22). Among high volume centers, the decision to transplant and to prioritize patients with COVID-related lung disease did not significantly impact the waitlist mortality of other candidates.

ABO-adjusted cPRA metric for kidney allocation in an Asian-predominant population.

Recent studies showed that ABO-adjusted calculated panel reactive antibody (ABO-cPRA) may better reflect the histocompatibility level in a multi-ethnic population, but such data in Asians is not available. We developed an ABO-adjusted cPRA metric on a cohort of waitlist kidney transplant patients (n = 647, 99% Chinese) in Hong Kong, based on HLA alleles and ABO frequencies of local donors. The concordance between the web-based ABO-cPRA calculator and the impact on kidney allocation were evaluated. The blood group distribution for A, B, O and AB among waitlist kidney candidates were 26.2%, 27.5%, 40.1%, and 6.1%, and their chances of encountering incompatible blood group donors were 32.6%, 32.4%, 57.6%, and 0%, respectively. There is poor agreement between web-based ABO-cPRA calculator and our locally developed metrics. Over 90% of patients showed an increase in cPRA after ABO adjustment, most notably in those with cPRA between 70% and 79%. Blood group O patients had a much greater increase in cPRA scores after adjustment while patients of blood group A and B had similar increment. 10.6% of non-AB blood group waitlist patients had ABO-cPRA elevated to ≥80%. A local ABO-adjusted cPRA metric is required for Asian populations and may improve equity in kidney distribution for patients with disadvantageous blood groups. The result from the current study potentially helps other countries/localities in establishing their own unified ABO-cPRA metrics and predict the impact on kidney allocation.

Review of the allocation criteria for heart transplant in Spain in 2023. SEC-Heart Failure Association/ONT/SECCE consensus document.

Heart transplant (HT) remains the best therapeutic option for patients with advanced heart failure (HF). The allocation criteria aim to guarantee equitable access to HT and prioritize patients with a worse clinical status. To review the HT allocation criteria, the Heart Failure Association of the Spanish Society of Cardiology (HFA-SEC), the Spanish Society of Cardiovascular and Endovascular Surgery (SECCE) and the National Transplant Organization (ONT), organized a consensus conference involving adult and pediatric cardiologists, adult and pediatric cardiac surgeons, transplant coordinators from all over Spain, and physicians and nurses from the ONT. The aims of the consensus conference were as follows: a) to analyze the organization and management of patients with advanced HF and cardiogenic shock in Spain; b) to critically review heart allocation and priority criteria in other transplant organizations; c) to analyze the outcomes of patients listed and transplanted before and after the modification of the heart allocation criteria in 2017; and d) to propose new heart allocation criteria in Spain after an analysis of the available evidence and multidisciplinary discussion. In this article, by the HFA-SEC, SECCE and the ONT we present the results of the analysis performed in the consensus conference and the rationale for the new heart allocation criteria in Spain.