Transplant Allocation Research Articles

MO923PREDICTING POST-TRANSPLANT HRQOL TO OPTIMIZE OUTCOMES IN OLDER KIDNEY TRANSPLANT RECIPIENTS

Abstract Background and Aims Kidney transplantation (KT) is the optimal treatment for older patients in need for kidney replacement therapy, with favorable outcomes both on survival, and health-related quality of life (HRQoL). Given the current organ scarcity, allocation of transplants should prioritize patients who are expected to benefit most from KT and identifying reliable predictors of post-transplant HRQoL outcomes is essential to optimize the selection process. Method Patients ≥ 65 years, who were enlisted for KT between January 2013 and November 2016 at the Norwegian national transplant center, were asked to participate. Self-reported HRQoL was assessed using the Kidney-Disease Quality of Life Short Form version 1.3 (KDQOL-SF) survey. Pre-transplant comorbidity was assessed by the Liu comorbidity index (LCI). Linear mixed-effect models were used to detect HRQoL changes over time (pre-KT, at -6, -12 and -36 months post-KT), and to identify pre-transplant predictors of post-transplant outcomes. Results By November 2020, 220 (76%) out of 289 enrolled participants, were transplanted. The mean age at KT was 71.8 (4.1) years, 154 (70%) were males, 57 (26%) were transplanted pre-emptively and 30 (13.6%) received a transplant from a living donor. Longer dialysis vintage was independently associated with impaired physical function post-transplantion (Figure 1). Pre-transplant LCI score ≥ 7 consistently predicted poorer HRQoL outcomes at baseline and after 3-years, compared with LCI score < 7 (Figure 2). At 3- years post-transplant, increasing LCI score was lineary associated with decreasing SF-36 scores. Recipients on dialysis for ≥ 1 year with LCI ≥ 7 experienced the worst outcomes, with a marked and sustained post-transplant physical deterioration (Figure 3). Conclusion Older wait-listed candidates either on dialysis for >1 year or with elevated pre-transplant LCI are at high risk for impaired HRQoL post-transplant outcomes and should be re-evaluated with respect to transplantability on a regular basis. The identification of criteria to optimize the selection of older transplant candidates should be the scope of future studies

The Heterogenous Effect of COVID-19 on Liver Transplantation Activity and Waitlist Mortality in the United States.

Background: The COVID-19 pandemic curtailed the practice of liver transplantation (LT), which lacks a temporizing life-saving measure for candidates on the waitlist.Aims/Objectives: The objective of this research was to (1) determine the effect of decreased LT activity on waitlist mortality in the United States and (2) assess if this effect was homogenous across the country.Methods: We conducted a retrospective, cross-sectional analysis utilizing United Network for Organ Sharing (UNOS) data assessing 3,600 liver transplants from January 1, 2020 to June 2, 2020. COVID-19 incidence data was taken directly from the New York Times case count.Results: During weeks 10 to 15 of 2020, there was a 38% reduction in the number of LTs performed nationally, which was temporally associated with a transient 97% increase in waitlist mortality. When stratified by UNOS region, waitlist mortality was inversely correlated with the number of LTs performed in all 11 regions. However, the range of the association strength (r) was large (Pearson correlation coefficient range: −0.73 to −0.01).Conclusion: Interruptions in LT activity due to COVID-19 were associated with rapid increases in waitlist mortality, and these effects were unevenly distributed among candidates across the United States. The transplant community can utilize these results to mitigate inequalities in transplant allocation between UNOS regions and advocate for the uninterrupted practice of LT should another pandemic surge or COVID-19 variant arise.

A novel prognostic model to predict outcome of artificial liver support system treatment

The prognosis of Artificial liver support system (ALSS) for hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is hard to be expected, which results in multiple operations of ALSS and excessive consumption of plasma, increase in clinical cost. A total of 375 HBV-ACLF patients receiving ALSS treatment were randomly divided a train set and an independent test set. Logistic regression analysis was conducted and a decision tree was built based on 3-month survival as outcome. The ratio of total bilirubin before and after the first time of ALSS treatment was the most significant prognostic factor, we named it RPTB. Further, a decision tree based on the multivariate logistic regression model using CTP score and the RPTB was built, dividing patients into 3 main groups such as favorable prognosis group, moderate prognosis group and poor prognosis group. A clearly-presented and easily-understood decision tree was built with a good predictive value of prognosis in HBV-related ACLF patients after first-time ALSS treatment. It will help maximal the therapeutic value of ALSS treatment and may play an important role in organ allocation for liver transplantation in the future.

Changes in Wait List Mortality, Transplantation Rates and Early Post-Transplant Outcomes in LVAD BTT with New Heart Transplant Allocation Score. A UNOS Database Analysis

PurposeTo evaluate the effect of the new heart transplant allocation system on LVAD supported patients listed as bridge to transplantation (BTT).MethodsAdult patients, who were listed for heart transplant between October 1,2016 and September 30, 2019, and were supported with an LVAD, enrolled in the UNOS database were enrolled in this study. Patients were classified according in the old or new system if they were listed or transplanted before or after October 18, 2018.ResultsA total of 2184 LVAD patients were listed for transplant. Of these, 1229 were classified in the old and 955 in the new system. The cumulative incidence of death or removal from the transplant list due to worsening clinical status, 1 year after listing, was lower in the new system (5% vs. 9%, p<0.001). Patients listed in the new system had a lower frequency of transplantation within 1 year of listing (52% vs. 60%, p=0.004) (Figure 1). A total of 1086 and 853 patients were transplanted in the old and new systems, respectively. Patients who were transplanted in the new system were more likely to receive a Hep C (+) donor heart and had a longer ischemic time. The 6 months post-transplant survival was 93.2% and 91.5% for the old and new systems, respectively (p=0.18).ConclusionWith the implementation of the new HT allocation system, LVAD-BTT patients have a lower frequency of transplantation and similar short-term post-transplant survival. LVAD-BTT patients are more likely to receive Hep C (+) donor hearts. To evaluate the effect of the new heart transplant allocation system on LVAD supported patients listed as bridge to transplantation (BTT). Adult patients, who were listed for heart transplant between October 1,2016 and September 30, 2019, and were supported with an LVAD, enrolled in the UNOS database were enrolled in this study. Patients were classified according in the old or new system if they were listed or transplanted before or after October 18, 2018. A total of 2184 LVAD patients were listed for transplant. Of these, 1229 were classified in the old and 955 in the new system. The cumulative incidence of death or removal from the transplant list due to worsening clinical status, 1 year after listing, was lower in the new system (5% vs. 9%, p<0.001). Patients listed in the new system had a lower frequency of transplantation within 1 year of listing (52% vs. 60%, p=0.004) (Figure 1). A total of 1086 and 853 patients were transplanted in the old and new systems, respectively. Patients who were transplanted in the new system were more likely to receive a Hep C (+) donor heart and had a longer ischemic time. The 6 months post-transplant survival was 93.2% and 91.5% for the old and new systems, respectively (p=0.18). With the implementation of the new HT allocation system, LVAD-BTT patients have a lower frequency of transplantation and similar short-term post-transplant survival. LVAD-BTT patients are more likely to receive Hep C (+) donor hearts.

Best Possible Use of a Donor Organ: Is There a Need for Age Matching in Heart Transplant Allocation?

<h3>Purpose</h3> The rate of heart transplantation (HTx) in adults, particularly in patients 65 years and older is rapidly increasing, 40% in the last five years. The purpose of this study is to characterize the donors used by older adults and investigate the effect of donor age on post-transplant survival for different age recipients. <h3>Methods</h3> The United Network for Organ Sharing (UNOS) database was used to identify HTx recipients ≥18yo from 1987 to 2020. Recipients were divided into four groups [18-49, 50-59, 60-64, and ≥65 years old (yo)]. Corresponding donors were divided into three groups (12-24, 25-39, ≥40yo). Post-transplant benefit was compared between combinations of recipient and donor age groups. <h3>Results</h3> 66,201 heart transplant recipients were identified. Recipient age groups: 18-49yo (34%, n=22,341), 50-59yo (35%, n=23,358), 60-64yo (18%, n=11,999), ≥65yo (13%, n=8,503). ≥65yo recipients were 13% of all transplants, utilized 10% of 12-24yo donors, 12% of 25-39yo donors and 17% of ≥40yo donors. Younger donor age provided greater benefit for younger recipients [<b>Figure</b>]. The improvement in median post-transplant survival (years) from using a 12-24yo donor instead of a ≥40yo donor was greatest in the 18-49yo recipient group (3yr benefit) compared to the ≥65yo recipient group (1yr benefit): 18-49yo recipients [13.8yrs (95% CI:13.3-14.2) with 12-24yo donors to 10.9yrs (10.4-11.4) with ≥40yo donors] vs. ≥65yo recipients [10.3yrs (9.8-10.0) with 12-24yo donors to 9.0yrs (8.5-9.6) with ≥40yo donors]. <h3>Conclusion</h3> There is a disproportionate (3x) benefit in median survival by using a younger donor heart (12-24yo) in younger recipients (18-49yo) compared to ≥65yo recipients. The potential gain in number of total post-transplant years by an age-specific organ allocation should be considered in this supply-constrained climate of transplant "economics".

Contemporary Outcomes for Cardiogenic Shock Patients Bridged to Advanced Heart Therapies with Temporary Mechanical Circulatory Support

<h3>Purpose</h3> The use of temporary mechanical circulatory support (tMCS) as a bridge to advanced heart replacement therapies (HRT) has increased in the context of the new heart transplant allocation system. As such, it is important to assess contemporary outcomes for this patient population. The purpose of this study was to assess outcomes of cardiogenic shock patients that were bridged with tMCS to HRT since the allocation system changes. <h3>Methods</h3> All adult cardiogenic shock patients that were bridged with tMCS to either heart transplantation (OHT) or durable left ventricular assist device (LVAD) at our center between October 2018 and September 2020 were identified. The tMCS devices included extracorporeal membrane oxygenation (ECMO), Impella, or temporary surgical VAD. Early and late clinical outcomes were assessed. <h3>Results</h3> A total of 33 cardiogenic shock patients were bridged to HRT using tMCS devices (OHT = 12, LVAD = 21). Most patients were male (84.9%) and the median age for all patients was 53 years. In terms of initial tMCS therapy, ECMO was used most commonly (64%) followed by Impella (24%) and temporary surgical VAD (12%). Ten patients (30%) required a second bridge-to-bridge device prior to HRT. Median duration of tMCS support for OHT and LVAD patients were 15.5 days (IQR 6.25-25) and 8 days (IQR 5-18.5), respectively. There were no in-hospital or 30-day mortality events. There was one late death in the VAD group at 16 months. Kaplan-meier curve (Figure 1) shows overall survival with median follow up of 8 months. <h3>Conclusion</h3> Cardiogenic shock patients can be bridged to HRT using contemporary tMCS technology and management with excellent early- and mid-term outcomes.

Heart Transplant Allocation Change Results in Increased Cost and Initial Decrease in Transplant Volume: The Florida Experience

PurposeIn October 2018, the United Network for Organ Sharing (UNOS) implemented a change in orthotopic heart transplant allocation policy in an effort to better stratify the most urgent transplant candidates.MethodsWe aimed to identify the impact of this policy change in Florida using an Interrupted Time Series Analysis (ITSA) technique. The 2016-2019 Florida Agency for Health Care Administration Inpatient data was queried for patients undergoing orthotopic heart transplantation. Patients <18 years of age were excluded in analysis. Patient demographics, before and after implementation of the UNOS allocation policy change, were evaluated using chi square and t-test; p≤0.05 was considered significant. These included Charlson Comorbidity Index, various post-operative outcomes, and hospital length of stay (LOS). Separate ITSA models were implemented to compare unit change in the number of transplants and total gross hospital charges.ResultsA total of 759 heart transplants were performed in Florida from 2016-2019. Data were compared before and after the allocation change: between 2016Q1-2018Q3 and 2018Q4-2019Q4. We found no difference with respect to post-operative outcomes, anesthesia or ICU charges, or total LOS (40.7 vs 39.3 days; p>0.05) before and after the policy change; however, total hospital charges differed significantly ($932,930 vs $1,167,889; p<0.05). ITSA modeling revealed a significant increase in total transplant charges after policy change, with an initial decrease in transplant volume (-17.8 transplants; 95% CI, -8.9 to -26.8, p<0.001) (Figure 1).ConclusionThe change in UNOS heart transplant allocation policy resulted in a decrease in transplant volume along with a significant increase in total transplant charges but without an associated increase in hospital LOS or ICU charges. These increased charges may be due to an increase in transport/travel charges. In October 2018, the United Network for Organ Sharing (UNOS) implemented a change in orthotopic heart transplant allocation policy in an effort to better stratify the most urgent transplant candidates. We aimed to identify the impact of this policy change in Florida using an Interrupted Time Series Analysis (ITSA) technique. The 2016-2019 Florida Agency for Health Care Administration Inpatient data was queried for patients undergoing orthotopic heart transplantation. Patients <18 years of age were excluded in analysis. Patient demographics, before and after implementation of the UNOS allocation policy change, were evaluated using chi square and t-test; p≤0.05 was considered significant. These included Charlson Comorbidity Index, various post-operative outcomes, and hospital length of stay (LOS). Separate ITSA models were implemented to compare unit change in the number of transplants and total gross hospital charges. A total of 759 heart transplants were performed in Florida from 2016-2019. Data were compared before and after the allocation change: between 2016Q1-2018Q3 and 2018Q4-2019Q4. We found no difference with respect to post-operative outcomes, anesthesia or ICU charges, or total LOS (40.7 vs 39.3 days; p>0.05) before and after the policy change; however, total hospital charges differed significantly ($932,930 vs $1,167,889; p<0.05). ITSA modeling revealed a significant increase in total transplant charges after policy change, with an initial decrease in transplant volume (-17.8 transplants; 95% CI, -8.9 to -26.8, p<0.001) (Figure 1). The change in UNOS heart transplant allocation policy resulted in a decrease in transplant volume along with a significant increase in total transplant charges but without an associated increase in hospital LOS or ICU charges. These increased charges may be due to an increase in transport/travel charges.

Improved Access to Heart Re-Transplantation with the New Heart Transplant Allocation System

<h3>Purpose</h3> To evaluate the effect of the new heart transplant allocation system on patients listed for re-transplantation. <h3>Methods</h3> Adult patients, who were listed for heart re-transplant between Jan 1, 2017 and September 30, 2019, enrolled in the UNOS database were included in this study. Patients were classified in the old or new system if they were listed or re-transplanted before or after October 18, 2018, respectively. <h3>Results</h3> A total of 214 patients were listed for re-transplant in the study period. Of these, 127 and 87 patients were classified in the <i>old</i> and <i>new</i> systems, respectively. Patients listed in the new system had a higher frequency of transplantation within 1 year of listing (HR: 1.63 (1.23-2.17), p=0.001) (Figure 1A). Patient listed for re-transplant in the new system had a higher frequency of ECMO (16.1% vs. 6.8%, p=0.037) and IABP (20.7% vs. 4.7%, p=0.001) support. A total of 72 and 93 patients were re-transplanted in the old and new systems, respectively. Clinical characteristics did not differ between re-transplanted patients in old vs. new systems. The 1-year post-transplant survival was 91.5% and 86.4% for the old and new systems, respectively (Figure 1B, p=0.35). <h3>Conclusion</h3> With the implementation of the new HT allocation system, Patients listed for re-transplantation have an increased access to a second heart transplant with similar 1-year post-re-transplant survival.

Impact of the New UNOS Heart Transplant Allocation System on Waitlist and Early Post-Transplant Mortality among Adults with Congenital Heart Disease

<h3>Purpose</h3> Adults with congenital heart disease (ACHD) are more likely to die or be delisted while awaiting heart transplant, less likely to receive a heart transplant and more likely to die in the early (30-day) post-transplant period compared to non-ACHD patients. On October 18, 2018; the UNOS heart allocation system was redesigned providing unique listing status for ACHD patients. The impact of this change on outcomes is unstudied. <h3>Methods</h3> Using the Scientific Registry of Transplant Recipients we compared ACHD patients listed for the first-time for heart transplant from 2 eras of equal duration (new era: October 18, 2018 to June 2, 2020 and prior era: March 3, 2017 to October 17, 2020). Patients with transplants occurring in the new era who were initially listed in the prior era were excluded. We compared baseline characteristics, Kaplan Meier curves and log-rank tests to assess differences in early post-transplant mortality and the composite of waitlist mortality or delisting due to clinical worsening among those with CHD between both eras. <h3>Results</h3> Out of 535 ACHD patients listed, 293 were in the new era (4.7% of total listings) and 242 were in the prior era (3.7%). Age, sex, racial distribution, renal function, hemodynamics and need for ECMO were identical between the two groups. 163 (56%) ACHD patients in the new era versus 150 (62%) in the prior era were transplanted; 11 (3.8%) versus 15 (6.2%) died on the waitlist; 32 (11%) versus 35 (14%) were delisted and 15 (9.2%) versus 19 (12.7%) died within 30 days of transplant respectively. In the new era, ACHD patients were significantly less likely to experience waitlist mortality or delisting due to clinical worsening but had similar early post-transplant mortality compared to the prior era. <h3>Conclusion</h3> The new UNOS heart transplant allocation system improved waitlist outcomes among ACHD patients listed for heart transplant.

The Waiting Game: Waitlist Times and Outcomes for Highly Sensitized Patients in the New Heart Transplant Allocation System

<h3>Purpose</h3> In 2018, United Network of Organ Sharing (UNOS) changed the heart allocation system to better stratify higher acuity patients and provide more equitable geographic distribution. However, they did not prioritize recipient allosensitization which can be a barrier to organ access. We analyzed outcomes based on sensitization in the modern era and the impact of the new allocation system on sensitized patients. <h3>Methods</h3> UNOS data from 3/31/2015-6/12/2020 was analyzed. Multi-organ transplants were excluded. Recipient, donor, and transplant characteristics were analyzed. Patients were stratified by cPRA level 0, 1-49, 50-79, and ≥ 80. Waitlist days prior to transplant, survival, and treated rejection pre and post allocation system change were analyzed. Survival was estimated using Kaplan-Meier methods and the log-rank test. <h3>Results</h3> Total of 10598 patients were included and evaluated by cPRA (Table). Patients with higher cPRA were more likely to be younger, African American, and female. Higher cPRA patients weighed less and were more likely to have non-ischemic cardiomyopathy, congenital disease, or be a retransplant. Waitlist days were significantly lower in the new allocation system for cPRA groups 0, 1-49, and 50-79 (p<0.0001) and there was a trend toward fewer waitlist days for cPRA ≥ 80 (p=0.062). Treated rejection during the transplant hospitalization and in the first year was significantly higher as cPRA increased (p<0.0001). However, when compared pre- and post-allocation change, there was no significant difference in long term survival across cPRA groups (p=0.531). <h3>Conclusion</h3> The new heart allocation system did not discriminate against sensitization, but rather facilitated a reduction in wait time for all but the most highly sensitized recipients. This may relate to increased access to appropriately matched donor organs through broader geographic sharing, but further investigation is needed.

Racial Differences in In-Hospital Outcomes after the Use of Temporary Mechanical Circulatory Support as a Bridge to Heart Transplant

Purpose The use of temporary mechanical circulatory support (tMCS) as a bridge to heart transplant (HTx) (BTT) has increased over time, especially after implementation of the new adult heart allocation system. We sought to assess if racial differences existed in in-hospital outcomes among patients BTT with a tMCS. Methods The National Inpatient Sample was queried for all patients who were BTT with a tMCS [intra-aortic balloon pumps (IABP), percutaneous left-ventricular assist device (PVAD), or extracorporeal membrane oxygenation (ECMO)] between 2008 and 2017. Patients were stratified by race and evaluated for in-hospital, death, MACE, discharge disposition, and costs. Multivariable logistic regression was used to identify predictors of in-hospital mortality for each of the tMCS devices. Results Out of 5,063 HTx, 17.8% (901) who were bridged with a tMCS (IABP 577, ECMO 366, PVAD 80). The incidence of MACE (9.7% White vs. 8.6% Black vs. 9.0% Hispanic vs. 7.6% Others; p value 0.520), non-home discharge (17.5% White vs. 17.1% Black vs. 12.6% Hispanic vs. 15.5% Others; p value 0.056) and procedural costs [White $354,406.72 vs. Black $329,752.47 vs. Hispanic $482,146.45 vs. Others $384,841.00; p value p Conclusion Among patients BTT with a tMCS, there was no racial difference in in-hospital complications or death, irrespective of the type of tMCS used. With the recent change in the transplant allocation system, the use of tMCS as a BTT has increased, and the results herein highlight that in-patient outcomes prior to the allocation system change are similar among racial groups and may ensure equitable access to transplantation in the new system.

Renal transplantation outcomes in obese patients: a French cohort-based study

BackgroundWhilst there are a number of publications comparing the relationship between body mass index (BMI) of kidney transplant recipients and graft/patient survival, no study has assessed this for a French patient cohort.MethodsIn this study, cause-specific Cox models were used to study patient and graft survival and several other time-to-event measures. Logistic regressions were performed to study surgical complications at 30 days post-transplantation as well as delayed graft function.ResultsAmong the 4691 included patients, 747 patients were considered obese with a BMI level greater than 30 kg/m2. We observed a higher mortality for obese recipients (HR = 1.37, p = 0.0086) and higher risks of serious bacterial infections (HR = 1.24, p = 0.0006) and cardiac complications (HR = 1.45, p < 0.0001). We observed a trend towards death censored graft survival (HR = 1.22, p = 0.0666) and no significant increased risk of early surgical complications.ConclusionsWe showed that obesity increased the risk of death and serious bacterial infections and cardiac complications in obese French kidney transplant recipients. Further epidemiologic studies aiming to compare obese recipients versus obese candidates remaining on dialysis are needed to improve the guidelines for obese patient transplant allocation.

Use of Measurable Residual Disease to Evolve Transplant Policy in Acute Myeloid Leukemia: A 20-Year Monocentric Observation.

Simple SummaryUpfront genetics/cytogenetics and minimal measurable disease (MRD) are becoming relevant biomarkers in the process of post-remission transplant allocation in AML. However, until recently the transplantation choice relied on the availability of a fully matched familiar donor, whereas individual patient- and disease-related characteristics played a secondary role in transplant allocation. In this paper we analyzed the evolution of the transplantation policy at our center in a 20-year time interval. At the beginning of our observation patients were submitted to allogeneic transplant, per protocol, mostly if a fully matched family donor was available or to autologous transplant if no fully matched family donor was identified (“donor vs. no donor” strategy) regardless of upfront genetics/cytogenetics or MRD status. Thereafter, persistence of MRD after consolidation cycle was included in the decision-making process for transplant selection. Patients with favorable and intermediate-risk cytogenetic risk were to receive allogeneic or autologous stem cell transplantation if MRD positive or negative, respectively, (“transplant vs. no transplant” strategy). In this cohort, patients with FLT3-ITD or adverse risk karyotype were submitted to allogeneic transplant as well. Measurable residual disease (MRD) is increasingly employed as a biomarker of quality of complete remission (CR) in intensively treated acute myeloid leukemia (AML) patients. We evaluated if a MRD-driven transplant policy improved outcome as compared to a policy solely relying on a familiar donor availability. High-risk patients (adverse karyotype, FLT3-ITD) received allogeneic hematopoietic cell transplant (alloHCT) whereas for intermediate and low risk ones (CBF-AML and NPM1-mutated), alloHCT or autologous SCT was delivered depending on the post-consolidation measurable residual disease (MRD) status, as assessed by flow cytometry. For comparison, we analyzed a matched historical cohort of patients in whom alloHCT was delivered based on the sole availability of a matched sibling donor. Ten-years overall and disease-free survival were longer in the MRD-driven cohort as compared to the historical cohort (47.7% vs. 28.7%, p = 0.012 and 42.0% vs. 19.5%, p = 0.0003). The favorable impact of this MRD-driven strategy was evident for the intermediate-risk category, particularly for MRD positive patients. In the low-risk category, the significantly lower CIR of the MRD-driven cohort did not translate into a survival advantage. In conclusion, a MRD-driven transplant allocation may play a better role than the one based on the simple donor availability. This approach determines a superior outcome of intermediate-risk patients whereat in low-risk ones a careful evaluation is needed for transplant allocation.

Increased frequency of heart transplantation, shortened waitlist time and preserved post-transplant survival in adults with congenital heart disease, on the new heart transplant allocation system.

Historically, adult congenital patients have longer waitlist time and worse outcomes on the heart transplant waitlist as well as poorer early post-transplant survival. A new heart transplantation allocation system was implemented in the United States on October 18, 2018. The effect of the new allocation system on adult congenital patients is unknown. Adult congenital patients listed for transplantation between November 1, 2015 and September 30, 2019 registered in the United Network for Organ Sharing were included in the study. October 18, 2018 was used as the limit to distribute listed and transplanted patients into old and new groups. A total of 399 patients were listed for heart transplant only, 284 in the old system and 115 in the new system. Clinical characteristics were similar between both groups. The cumulative incidence of poor outcome on the transplant list was similar in both groups (P=.23), but the cumulative incidence of transplant was higher in the new system group (P<.009) and was associated with a shorter waitlist time. The one-year post-transplant outcome was similar between old and new groups (P=.37). The new allocation system has benefited adult congenital patients with increased cumulative frequency of transplantation without worsening short-term survival after transplantation.

Editorial introductions.

Editorial introductions.

Implantation Strategies to Protect the Total Artificial Heart for Subsequent Heart Transplantation

Re-entry into the chest after one or more previous operative interventions can result in prolonged dissection, blood loss, structural damage, and catastrophic injuries, resulting in MOF and even death. Previous implantation of mechanical circulatory assist devices may lead to development of dense adhesions and solid scar tissue. This is certainly true for cases involving previous placement of the total artificial heart (TAH). Implantation of this device is on the rise, as is it is the only viable options for patients with biventricular failure, as the number of heart transplantations is stagnant worldwide. With the new heart transplantation allocation system in the United States, more and more patients with an implanted TAH are waiting for cardiac transplantation. Therefore, patients having an implanted TAH presenting for transplantation are at risk for complications during sternal re-entry or for complications as a result of prolonged ischemic time due to extended times of mediastinal dissection. Thoughtful and preemptive preparation of the surgical field at the time of initial implantation of the TAH has not only the potential, but a proven track record of decreasing operative time, duration of mediastinal dissection as well as risks for complications and adverse events in patients with subsequent heart transplantation. In conclusion, the measures for TAH protection taken at the time of implantation allow for expeditious and safe redo sternotomy, efficient mediastinal dissection, rapid identification and exposure of structures necessary for initiation of cardiopulmonary bypass and finally and importantly expeditious device removal in order to avoid delay in donor organ implantation and prolonged ischemic time.

Adversarial Learning on Incomplete and Imbalanced Medical Data for Robust Survival Prediction of Liver Transplant Patients

The scarcity of liver transplants necessitates prioritizing patients based on their health condition to minimize deaths on the waiting list. Recently, machine learning methods have gained popularity for automatizing liver transplant allocation systems, which enables prompt and suitable selection of recipients. Nevertheless, raw medical data often contain complexities such as missing values and class imbalance that reduce the reliability of the constructed model. This paper aims at eliminating the respective challenges to ensure the reliability of the decision-making process. To this aim, we first propose a novel deep learning method to simultaneously eliminate these challenges and predict the patients’ survival chance. Secondly, a hybrid framework is designed that contains three main modules for missing data imputation, class imbalance learning, and classification, each of which employing multiple advanced techniques for the given task. Furthermore, these two approaches are compared and evaluated using a real clinical case study. The experimental results indicate the robust and superior performance of the proposed deep learning method in terms of F-measure and area under the receiver operating characteristic curve (AUC).

SURVIVAL TREE SCORE: A NOVEL APPROACH TO PREDICT MORTALITY IN CIRRHOTIC PATIENTS

Although Model for End-Stage Liver Disease (MELD) score is adopted worldwide for liver transplant allocation, but it has prognostic limitations. The aim of this study was to apply the survival tree analysis to evaluate interaction between variables related to mortality in cirrhotics patients enlisted for liver transplantation, and to develop a new mortality predictive score. Demographic, clinical and laboratory data of cirrhotic patients waiting for liver transplantation during a 12-year period were considered. Charts from 765 patients were reviewed. The interaction between prognostic covariates was obtained using a survival tree analysis. In order to develop the predictive score, Cox regression analysis was performed applying significant data obtained by the survival tree analysis. The prognostic covariates evaluated in the survival tree were MELD score, Child-Pugh score, serum sodium, viral disease etiology, hepatocellular carcinoma diagnosis and generated a coefficient for each. Based on the survival tree analysis, MELD = 15 was the primary root variable (p&lt;0.001). The survival tree provided eight prognostic groups. The higher mortality hazard ratio (HR) risk was observed in the MELD &gt;28 group (HR= 16.7). The new score (Survival Tree Score – STS) was obtained according to the coefficients provided. The STS prognostic performance was superior to MELD score (AUROC 0.713 vs 0.653, p&lt;0.001). STS, could be a useful tool to accurately identify individual mortality risk in advanced liver disease.

Navigating the COVID-19 pandemic: Initial impacts and responses of the Organ Procurement and Transplantation Network in the United States.

COVID‐19 has been sweeping the globe, hitting the United States particularly hard with a state of emergency declared on March 13, 2020. Transplant hospitals have taken various precautions to protect patients from potential exposure. OPTN donor, candidate, and transplant data were analyzed from January 5, 2020 to September 5, 2020. The number of new waiting list registrations decreased, with the Northeast seeing over a 50% decrease from the week of 3/8 versus the week of 4/5. The national transplant system saw near cessation of living donor transplantation (−90%) from the week of 3/8 to the week of 4/5. Similarly, deceased donor kidney transplant volume dropped from 367 to 202 (−45%), and other organs saw similar decreases: lung (−70%), heart (−43%), and liver (−37%). Deceased donors recovered dropped from 260 to 163 (−45%) from 3/8 compared to 4/5, including a 67% decrease for lungs recovered. The magnitude of this decrease varied by geographic area, with the largest percent change (−67%) in the Northeast. Despite the pandemic, discard rates across organ has remained stable. Although the COVID‐19 pandemic continues to evolve, OPTN data show recent evidence of stabilization, an indication that an early recovery of the number of living and deceased donors and transplants has ensued.

Changes in Heart Transplant Allocation Policy: "unintended" Consequences but Maybe Not so "unexpected…".

To the Editor: We read with great interest the article of JR Trivedi & MS Slaughter, which reported a dramatic increase in the number of patients listed and transplanted on acute mechanical support and in posttransplant mortality following the implementation of the new US heart transplantation (HTx) allocation scheme.1 Although not intended, these results may not be unexpected. Allocation schemes that prioritize patients according to the medical therapy they receive have always influenced medical practice. Gaming the waitlist by using unnecessary multiple inotrope therapy has already been demonstrated in the United States.2 Whereas its hemodynamic impact is minimal and it has not been shown to have any survival benefit in cardiogenic shock, the intraaortic balloon pump (IABP) has been given a high priority status in the new scheme.3 We believe that IABP represents a prototypal candidate for gaming the waitlist since the benefits in prioritization clearly outweigh the risks associated with this minimally invasive support. On reflection, the proportion of patients transplanted with IABP increased from 9% to 33%. The prioritization of HTx candidates based on an individual score, not taking into account medical practices but keeping the same principle of the “sickest first,” as has been the case in France since 2018, may be an attractive approach to avoid these drifts.4 A remaining key challenge for allocation is to estimate posttransplant mortality to avoid futile transplantations. The high scrutiny of US agencies has always been effective in maintaining excellent posttransplant results,5 but the recent scheme changes may have increased the number of high-risk HTx. In France, the high priority status given to patients on extracorporeal membrane oxygenator (ECMO) has been initially associated with very high-risk transplantations with unacceptably high posttransplant mortality.6 This has led to HTx being contraindicated for ECMO patients with a glomerular filtration rate below 40 ml/min. In our current allocation scheme, an individual scoring system allows the stratification of the risk of early posttransplant death and contraindicates very high-risk HTx.7 We believe that cardiac transplantation in patients previously stabilized with ECMO should not be seen as the devil, and the concept is different from bridging stable patients to transplantation with ECMO support, with the letter making no sense. Carefully selected ECMO patients can be excellent candidates for a direct HTx strategy. After the implementation of a specific ECMO protocol, which includes systematic reperfusion, percutaneous cannulation, IABP to unload the left ventricle, and an awake strategy, we reported favorable posttransplant outcomes for pre-HTx ECMO patients, comparable to those of patients without ECMO.8 In addition, survival benefit (the difference between survival after HTx and waiting list survival without HTx), which appears to be a more clinically relevant metric than the standard one-year posttransplant survival, is maximal for these patients.9,10 We think that the field of organ allocation would greatly benefit from international collaborative research, not only at the level of national agencies, but especially at the level of centers, which can provide both the heterogeneity between cohorts and highly phenotyped databases that are required to improve risk stratification and allocations schemes.