United Network For Organ Sharing Database Research Articles

Bridge to Heart Transplant With Temporary Mechanical Circulatory Support: Trends and Outcomes in the 2018 Allocation Policy Era.

The United Network for Organ Sharing (UNOS) 2018 heart allocation policy prioritizes patients receiving temporary mechanical circulatory support (tMCS) given the high waitlist mortality rate of this group. This study evaluates national trends and waitlist outcomes for patients receiving tMCS under the UNOS 2018 allocation policy. Adult patients waitlisted for isolated heart transplantation were included using the UNOS database. The prevalence of tMCS, 90 day waitlist mortality, 90 day incidence of transplantation, and posttransplant 1 year mortality were analyzed. A total of 27,343 patients were waitlisted during the study period (pre-policy change: 13,004 vs. post-policy change: 14,339). The prevalence of tMCS increased from 7.4% (n: 956) to 22.4% (n: 3,186) after the policy change (p < 0.001). The use of Impella increased proportionally among tMCS modalities. Patients on tMCS had lower adjusted odds of waitlist mortality (p < 0.001), higher adjusted incidence of transplantation (p < 0.001), and similar posttransplant mortality (p = 0.10) under the 2018 policy. Patients on extracorporeal membrane oxygenation (ECMO) support had the highest odds of 90 day waitlist mortality (p < 0.05) but also the highest incidence of transplantation in the post-policy change cohort (p < 0.05). In conclusion, the use of tMCS as bridge to heart transplantation increased threefolds and is associated with lower waitlist mortality and higher incidence of transplantation following the UNOS 2018 allocation policy change.

Short-Term Outcomes Among Lung Transplant Recipients from SARS-CoV-2+ Donors and Evaluation of Lung Function Among SARS-CoV-2+ Donors

There are reports of successful lung transplants using SARS-CoV-2+ donors, but the data on their overall outcome is limited. We used the United Network for Organ Sharing Database (UNOS) to identify all lung transplant patients who received lungs from SARS-CoV-2+ donors between 2020 and 2023. There was no difference in survival between those who received lungs from SARS-CoV-2- and SARS-CoV-2+ donors (p=0.60). In addition, the timing of the SARS-CoV-2 test for donors did not affect the outcomes among recipients. Among all SARS-CoV-2+ donors identified since 2020, the lungs used came from younger donors, had better chest x-ray findings, and had a higher P/F ratio. Our data suggest that organ function may be more important than SARS-CoV-2 status when using lungs from SARS-CoV-2+ donors. Further research and follow-up are still needed to adequately address the use of lungs from SARS-CoV-2+ donors, thus further increasing the donor pool.

Sex-mismatching in isolated heart transplantation confers no postoperative risk

BackgroundFor heart transplantation, optimal donor-recipient matching is an important factor in the ongoing development of the United Network for Organ Sharing (UNOS) continuous distribution framework. Donor-recipient sex-mismatch has decreased since the 1990s, but this may be related to the risk posed by size mismatching, particularly when donor hearts are undersized. Thus, the impact of sex-mismatching, controlling for other factors including size mismatch, is uncertain. MethodsAdult first-time, isolated heart transplant patients from the UNOS database between October 1, 1987 and December 31, 2022 were analyzed. Cohorts were separated into male and female recipients. Propensity score matching on known preoperative risk factors was performed. Equivalence testing via Two One-Sided Testing (TOST) was performed to assess between-arm equivalence in postoperative outcomes. Survival differences were measured by the between-arm ratio of Restricted Mean Survival Time and binary outcome differences by the Odds Ratio (OR). ResultsIn the propensity matched cohort, we found significant equivalence between arms in both male (TOST P<0.001) and female (TOST P<0.001) recipients for overall survival at all temporal endpoints, postoperative treatment for rejection within one year, and pre-discharge dialysis. ConclusionsSex-mismatch in isolated heart transplantation confers no additional risk to postoperative outcomes when controlling for other factors, including size mismatch. Consequently, sex-mismatch should not factor into individual assessments of organ acceptance or be incorporated into any national organ allocation policy. Increasing the acceptance of sex-mismatched donors has the potential to expand the donor pool and increase female donor utilization.

Long-Term Outcomes After Lung Transplantation in Children With Intellectual Disabilities.

The United Network for Organ Sharing (UNOS) started recording data on intellectual disability status in 2008. This study aimed to characterize the long-term outcomes for children with intellectual disabilities (IDs) undergoing lung transplantation. All pediatric patients (under 18 years old) undergoing bilateral lung transplantation were identified using the UNOS database. The patients were grouped into the following categories: no cognitive delay, possible cognitive delay, and definite cognitive delay. The primary endpoint was graft survival at 3-year posttransplantation. Multivariate Cox proportional hazards modeling was used to estimate the independent effect of cognitive disability on graft survival. Five hundred four pediatric patients who underwent lung transplantation between March 2008 and December 2022 were retrospectively analyzed. 59 had a definite cognitive delay (12%), 23 had a possible delay (5%), and 421 had no delay (83%). When comparing these three groups, there was no significant difference in 60-day graft survival (p = 0.4), 3-year graft survival (p = 0.6), 3-year graft survival for patients who survived at least 60-day posttransplantation (p = 0.9), distribution of causes of death (p = 0.24), nor distribution treatment of rejection within 1-year posttransplantation (p = 0.06). Intellectual disability does not impact long-term outcomes after bilateral lung transplantation. Intellectual disability should not be a contraindication to bilateral lung transplantation on the basis of inferior graft survival.

Survival outcomes following urgent lung transplantation in France and the USA

IntroductionLung graft allocation can be based on a score (Lung Allocation Score) as in the USA or sequential proposals combined with a discrete priority model as in France. We aimed...

Influence of socioeconomic factors on liver transplant survival outcomes in patients with autoimmune liver disease in the United States

Introduction and ObjectivesAutoimmune liver diseases (AILDs): autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC) have different survival outcomes after liver transplant (LT). Outcomes are influenced by factors including disease burden, medical comorbidities, and socioeconomic variables. Materials and MethodsUsing the United Network for Organ Sharing database (UNOS), we identified 13,702 patients with AILDs listed for LT between 2002 and 2021. Outcomes of interest were waitlist removal, post-LT patient survival, and post- LT graft survival. A stepwise multivariate analysis was performed adjusting for transplant recipient gender, race, diabetes mellitus, model for end-stage liver disease (MELD) score, and additional social determinants including the presence of education, reliance on public insurance, working for income, and U.S. citizenship status. ResultsLack of college education and having public insurance increased the risk of waitlist removal (HR, 1.13; 95 % CI, 1.05–1.23, and HR, 1.09; 95 % CI, 1.00–1.18; respectively), and negatively influenced post-LT patient survival (HR, 1.16; 95 % CI, 1.06–1.26, and HR, 1.15; 95 % CI, 1.06–1.25; respectively) and graft survival (HR, 1.13; 95 % CI, 1.05–1.23, and HR, 1.15; 95 % CI, 1.06–1.25; respectively). Not working for income proved to have the greatest detrimental impact on both patient survival (HR, 1.41; 95 % CI, 1.24–1.6) and graft survival (HR, 1.21; 95 % CI, 1.09–1.35). ConclusionsOur study highlights that lack of college education and public insurance have a detrimental impact on waitlist mortality, patient survival, and graft survival. Not working for income negatively affects post-LT survival outcomes. Not having U.S. citizenship does not affect survival outcomes in AILDs patients.

Predictors of Survival After Heart Transplant in the New Allocation System: A UNOS Database Analysis.

Clinical predictors of posttransplant graft loss since the United Network for Organ Sharing (UNOS) heart allocation system change have not been well characterized. Single organ adult heart transplants from the UNOS database were identified (n = 10,252) and divided into a test cohort (n = 6,869, 67%) and validation cohort (n = 3,383, 33%). A Cox regression analysis was performed on the test cohort to identify recipient and donor risk factors for posttransplant graft loss. Based on the risk factors, a score (max 16) was developed to classify patients in the validation cohort into risk groups of low (≤1), mid (2-3), high (≥4) risk. Recipient factors of advanced age, Black race, recipient blood group O, diabetes, etiology of heart failure, renal dysfunction, elevated bilirubin, redo-transplantation, elevated pulmonary artery pressure, transplant with a durable ventricular assist device, or transplant on extracorporeal membrane oxygenation (ECMO) or ventilator were associated with more posttransplant graft loss. Donor factors of ischemic time and donor age were also associated with outcomes. One year graft survival for the low-, mid-, high-risk groups was 94%, 91%, and 85%, respectively. In conclusion, easily obtainable clinical characteristics at time of heart transplant can predict posttransplant outcomes in the current era.

Increased disparities in waitlist and post-heart transplantation outcomes according to socioeconomic status with the new heart transplant allocation system

The study objective was to assess disparities in outcomes in the waitlist and post-heart transplantation (HT) according to socioeconomic status (SES) in the old and new U.S. HT allocation systems. Adult HT candidates in the United Network for Organ Sharingdatabase from 2014 through 2021 were included. Old or new system classification was according to listing before or after October 18, 2018. SES was stratified by patient ZIP code and median household income via U.S. Census Bureau and classified into terciles. Competing waitlist outcomes and post-transplantation survival were compared between systems. In total, 26,450 patients were included. Waitlisted candidates with low SES were more frequently younger, female, African American, and with higher body mass index. Reduced cumulative incidence (CI) of HT in the old system occurred in low SES (53.5%) compared to middle (55.7%, p=0.046), and high (57.9%, p<0.001). In the new system, the CI of HT was 65.3% in the low SES vs middle (67.6%, p=0.002) and high (70.2%, p<0.001), and SES remained significant in the adjusted analysis. In the old system, CI of death/delisting was similar across SES. In the new system, low SES had increased CI of death/delisting (7.4%) vs middle (6%, p=0.012) and high (5.4%, p=0.002). The old system showed similar 1-year survival across SES. In the new system, recipients with low SES had decreased 1-year survival (p=0.041). SES affects waitlist and post-transplant outcomes. In the new system, all SES had increased access to HT; however, low SES had increased death/delisting due to worsening clinical status and decreased post-transplant survival.

Donor supply for partial heart transplantation in the United States.

Congenital heart disease (CHD) is the most common cause of birth defects worldwide. Valvular defects are a common form of CHDs, and, at this time, treatment options for children with unrepairable valve disease are limited. Issues with anticoagulation, sizing, and lack of growth in valve replacement options can lead to high mortality rates and incidence of reoperations. Partial heart transplantation, or transplantation of fresh valve allografts, has recently been described as a strategy to provide a durable and non-thrombogenic alternative to conventional prostheses and provide growth potential in pediatric patients. The United Network for Organ Sharing (UNOS) database was queried to analyze the number of pediatric donor hearts that were not recovered but had viable valves (n=3565) between January 2010 and September 2021. Recoverable valves were grouped by donor age: infants (age<1year), toddlers (age ≥1 and <3years), and children (age ≥3 and <18years). Demographic characteristics of donors were analyzed between age groups. Infants, toddlers, and children had a total of 344, 465, and 2756 hearts with recoverable valves, respectively, over the study period, representing an average of 29, 39, and 230 hearts with recoverable valves per year. The results of our study identify the minimum donor supply for partial heart transplantation. The actual number is likely higher because it includes hearts not entered in the UNOS database and domino transplants from orthotopic heart transplant recipients. Partial heart transplantation is logistically feasible as there are recoverable valves available for all age groups, fulfilling a clinical need in pediatric patients with unrepairable valve disease.

Utilization and outcomes of rescue hepatectomy among U.S. liver retransplant candidates.

The frequency and outcomes of anhepatic patients listed for transplantation in the United States have not been studied. The United Network for Organ Sharing (UNOS) records anhepatic status for patients listed as Status 1A for hepatic artery thrombosis (HAT) or primary non-function (PNF). Using the UNOS database from 2005 to 2020, demographics and waitlist outcomes of anhepatic candidates relisted as Status 1A for HAT or PNF were assessed. Among 1364 adult Status 1A patients relisted for PNF or HAT across 120 distinct transplant centres, 75 (5.5%) patients were anhepatic and 1289 (94.5%) were non-anhepatic. A substantial number of centres (n=51) had experience with ≥1 anhepatic patient relisted for either PNF or HAT, with individual centre rates ranging from 0% to 11.4%. Waitlist mortality was more than twice as high for anhepatic patients: 42.5%versus 17.0% non-anhepatic patients (p<.001). The post-transplant outcomes of anhepatic patients were markedly inferior to non-anhepatic patients. For example, 41.9% of anhepatic patients died during the index admission versus 23.4% of the non-anhepatic group (p=.006). Patient survival for the anhepatic and non-anhepatic groups was 48.3%versus 66.2% at 1-year and 29.3%versus 46.2% at 5-years, respectively (log-rank test for overall survival p=.014). Rescue hepatectomy after initial liver transplantation is not only associated with high waitlist mortality, but also markedly worse post-transplant outcomes. With less than half of anhepatic patients surviving to the first year post-LT, further research is warranted to better delineate which patients should be considered for rescue hepatectomy.

Association of Donors With US Public Health Service Risk Criteria and Outcomes After Adult vs Pediatric Cardiac Transplant

The United Network for Organ Sharing (UNOS) evaluates donor risk for acute transmission of HIV, hepatitis B, or hepatitis C based on US Public Health Services (PHS)-specific criteria. However, recent data regarding use and outcomes of those donors with PHS risk criteria among pediatric and adult heart transplant recipients are lacking. To compare use and outcomes of graft from donors with PHS risk criteria vs those with a standard-risk donor (SRD) in children vs adults in a contemporary cohort. This cohort was a nationwide analysis of heart transplants in the US that used data from the UNOS database. Participants were children (<18 years old) and adults (≥18 years old) who received a heart transplant from January 1, 2010, to December 31, 2021. UNOS-defined donor risk status. Trend analysis compared changes in PHS risk criteria use among children and adults. Patient survival was analyzed using Kaplan-Meier curves with log rank and Cox proportional hazards to compare PHS risk-criteria outcomes vs SRD-criteria outcomes in children and adult heart transplant recipients. Additional analysis was performed among adults who received a PHS-risk criteria graft that was previously declined for pediatric recipients. Of 5115 pediatric transplant recipients (donor without PHS risk median [IQR] age, 5 [0-13] years and donor with PHS risk median [IQR] age, 8 [0-14] years) and 30 289 adult heart transplant recipients (donor without PHS risk median [IQR] age, 56 [46-63] years and donor with PHS risk median [IQR] age, 57 [47-63] years), PHS risk criteria comprised 8% in children vs 25% in adults. PHS criteria are being increasingly used over the past decade with the proportion of recipients transplanted with PHS risk-criteria donors being approximately 3 times greater among adult recipients than children recipients. Pediatric recipients of a PHS risk-criteria donor had greater pretransplant ventilatory support, whereas adult recipients of a PHS risk-criteria donor had greater pretransplant extracorporeal membrane oxygenation use. Patient survival was similar between pediatric recipients of PHS risk-criteria grafts vs SRD-criteria grafts and slightly higher among adult recipients of PHS risk-criteria grafts vs SRD-criteria grafts. The 1778 adult recipients who received a PHS criteria-risk donor that was previously declined for pediatric recipients had similar patient survival recipients compared with SRD-criteria donors (HR, 0.92; 95% CI, 0.81-1.03; P = .18). In the current era, a 3-fold greater proportion of adult recipients receive a PHS risk-criteria graft compared with children despite similar posttransplant patient survival. The ongoing organ donor shortage underscores the need for consideration of PHS risk criteria where these donors remain underused.

Characteristics, Predictors, and Outcomes of Early mTOR Inhibitor Use After Heart Transplantation: Insights From the UNOS Database.

BackgroundThe clinical characteristics of mTOR (mammalian target of rapamycin) inhibitors use in heart transplant recipients and their outcomes have not been well described.Methods and ResultsWe compared patients who received mTOR inhibitors within the first 2 years after heart transplantation to patients who did not by inquiring the United Network for Organ Sharing (UNOS) database between 2010 and 2018. The primary end point was all‐cause mortality with retransplantation as a competing event. Rejection, malignancy, hospitalization for infection, and renal transplantation were secondary end points. There were 1619 (9%) and 15 686 (81%) mTOR inhibitors+ and mTOR inhibitors− patients, respectively. Body mass index, induction, cardiac allograft vasculopathy, calculated panel reactive antibody, and fewer days in 1A status were independently associated with mTOR inhibitors+ status. Over a follow‐up of 10.4 years, there was no difference in all‐cause mortality after adjusting for donor and recipient characteristics (adjusted subdistribution hazard ratio, 1.03 [0.90–1.19]; P=0.66). mTOR inhibitors+ were independently associated with increased risk for rejection (odds ratio [OR], 1.43 [1.11–1.83]; P=0.005) and basal skin cancer (OR, 1.35 [1.19–1.51]; P=0.012) but not for infection or renal transplantation.ConclusionsmTOR inhibitors are used in <10% patients in the first 2 years after heart transplantation and are noninferior to contemporary immunosuppression regimens in terms of all‐cause mortality, infection, malignancy, or renal transplantation. They are associated with risk for rejection.

Solid organ transplantation from COVID positive donors in the United States: Analysis of United Network for Organ Sharing database.

BackgroundSignificant uncertainties remain regarding the utilization of organs for solid organ transplantation (SOT) from donors with coronavirus disease 2019 (COVID‐19). The aim of this study was to assess the trends in utilization of organs from donors with COVID‐19 and their short‐term outcomes.MethodsDeceased donors between March 2020 and December 2021 with a positive COVID nucleic acid test from respiratory tract within 14 days of transplantation were analyzed using the de‐identified United Network for Organ Sharing (UNOS) database. Donor and recipient characteristics of COVID‐19 positive (COVID+) organs were compared to COVID‐19 negative (COVID−) organs during this period. We analyzed the trends in the utilization of SOT from COVID+ donors across the United States, donor characteristics, and the quality of donor organ and recipient outcomes (length of hospitalization, rates of organ rejection, delayed graft function, 30‐day graft/patient survival).ResultsDuring the study period, 193 COVID+ donors led to the transplantation of 281‐kidneys, 106‐livers, and 36‐hearts in 414 adult recipients. COVID+ patients donated a median of two organs. These donors were younger and had a lower median Kidney Donor Profile Index (0.37 vs. 0.50, p < .001), lower median serum creatinine (0.8 vs. 1.0 mg/dl, p = .003), similar median serum total bilirubin (0.6 mg/dl, p = .46), and similar left ventricular ejection fraction (60%, p = .84) when compared to COVID− donors. Short‐term outcomes, including 30‐day graft/patient survival, were similar in both groups.ConclusionsAnalysis of short‐term outcomes from the UNOS database indicates that a positive COVID test in an otherwise medically suitable donor should not preclude consideration of non‐lung solid organ transplantation.

#10 Variation in Antibiotic Use and Incidence of Surgical Site Infections in Pediatric Liver Transplant Recipients

Abstract Background Surgical site infections (SSIs) are an important source of early complication after liver transplantation (LT). Peri-operative antibiotics to prevent SSI is considered standard of care, yet there are limited data on the frequency of SSI and no consensus on a standardized regimen. A major barrier is the lack of a large cohort of pediatric LT recipients. Leveraging merged data from the Pediatric Health Information System (PHIS) and the United Network for Organ Sharing (UNOS) we assembled a large cohort of pediatric LT patients to describe the frequency of SSI, variation in antibiotic prophylaxis practices and associated factors. Method The source cohort included all patients under 18 years in the UNOS database who received a LT at a PHIS-participating institution between January 1st 2006 to August 6th, 2017. We excluded those undergoing multi-visceral transplantation and/or re-transplantation. Patient data were merged using a probabilistic merge algorithm using the following present in both datasets: transplant center, date of birth, gender and date of transplant. Our primary outcome was any SSI present during the first 30 days of the hospitalization in which the LT was performed. SSI was defined using ICD 9 and ICD-10 diagnosis codes for post-operative surgical site infection, in addition to procedure codes for incision and drainage or return to the operating room. Peri-operative prophylaxis regimens were inclusive of antibiotic(s) received on the day of or day after LT. After all unique antibiotic regimens were identified, we further categorized into 6 levels of clinically relevant antibiotic combinations ranging from narrowest (Level 1 was cefazolin) to broadest spectrum (Level 6 was carbapenems). Patients receiving agents from more than one category defaulted to the broadest spectrum group. Vancomycin/linezolid administration was collected as a distinct covariate. Data collected on baseline factors included age at LT, sex, race, specifics of the LT type, and severity of illness (SOI) defined as receiving ICU level care on at least one day in the week prior to LT. Results Data from PHIS was successfully merged to 3055 (94%) of patients in the UNOS cohort. We excluded 264 multi-visceral transplants and/or re-transplants and 205 LT recipients without a categorizable antibiotic regimen with a final cohort of 2586 patients. This cohort was 50.8% female, 11.6% Black and 65% White with median age of 2 years (IQR of 0,9). 11.6% of patients required at least one ICU level of care day in the week prior to LT and the median hospital stay from day of transplant was 20 days (IQR: 13, 35). An SSI was identified during the hospital stay in 284 (11%) patients. As we discovered that patients less than 1-year of age at transplant were almost twice as likely to experience an SSI compared to patients over 1 year (16.2% versus 8.6%), the distribution of other covariates by antibiotic category was assessed after stratifying &amp;lt;1 year versus &amp;gt;=1 year (Table 1A and Table 1B).Category 5 was the most commonly represented antibiotic group.Significant differences in antibiotic regimen included donor type and type of liver transplanted , receipt of dialysis the week prior, and in those meeting SOI criteria. In older patients, differences in antibiotics administered were additionally noted within race category and if there was concern for donor infection. Conclusion SSI was common and varied by age, with children under one more likely to sustain an SSI. Antibiotic regimens administered varied withing each of these age groups. Factors associated broader-spectrum categories included receipt of a living donor LT, dialysis in the week prior to LT, and needing at least one ICU-level of care day in the week prior to LT. Additional multivariate analyses are warranted and will focus on investigating the degree to which center-specific differences are driving variation and will explore the comparative effectiveness of different antibiotic prophylaxis categories on SSI risk.

Impact of utilization of hepatitis C positive organs in liver transplant: Analysis of united network for organ sharing database.

BACKGROUNDThe utility of hepatitis C virus (HCV) organs has increased after the Food and Drug Administration approval of direct acting anti-viral (DAA) medications for the HCV treatment. The efficacy of DAA in treating HCV is nearly 100%. AIMTo analyze the United Network for Organ Sharing (UNOS) database to compare the survival rates between the hepatitis C positive donors and negative recipients and hepatitis C negative donors and recipients. METHODSWe analyzed the adult patients in UNOS database who underwent deceased donor liver transplant from January 2014 to December 2017. The primary endpoint was to compare the survival rates among the four groups with different hepatitis C donor and recipient status: (Group 1) Both donor and recipient negative for HCV (Group 2) Negative donor and positive recipient for HCV (Group 3) Positive donor and negative recipient for HCV (Group 4) Both positive donor and recipient for HCV. SAS 9.4 software was used for the data analysis. Kaplan Meier log rank test was used to analyze the estimated survival rates among the four groups. RESULTSA total of 24512 patients were included: Group 1: 16436, Group 2: 6174, Group 3: 253 and Group 4: 1649. The 1-year (Group 1: 91.8%, Group 2: 92.12%, Group 3: 87%, Group 4: 92.8%), 2-year (Group 1: 88.4%, Group 2: 88.1%, Group 3: 84.3%, Group 4: 87.5%), 3-year (Group 1: 84.9%, Group 2: 84.3%, Group 3: 75.9%, Group 4: 83.2%) survival rates showed no statistical significance among the four groups. Kaplan Meier log rank test did not show any statistical significance difference in the estimated survival rates between Group 3 vs all the other groups. CONCLUSIONThe survival rates in hepatitis C positive donors and negative recipients are similar as compared to both hepatitis C negative donors and recipients. This could be due to the use of DAA therapy with cure rates of nearly 100%. This study supports the use of hepatitis C positive organs in the selected group of recipients with and without HCV infection. Further long-term studies are needed to further validate these findings.

A Machine Learning Model for Post-Transplant Lymphoproliferative Disorder Using the UNOS Database

<h3>Purpose</h3> Post Transplant Lymphoproliferative Disorder (PTLD) is a complication noted in cardiac allograft recipients. This study was undertaken to generate a risk prediction model for PTLD at 1, 3 and 5 years post heart transplant using machine learning models. The United Network for Organ Sharing (UNOS) database was used for data generation <h3>Methods</h3> The UNOS database was probed from 1987 to 2015<b>.</b> After excluding retransplants and those with incomplete information regarding malignancy, 39696 adult patients were identified out of which 884 patients had PTLD. A Random Under-sampling Boosting ("RUSBoost") technique in combination with Decision Tree models ("ensemble of models") was used to create a PTLD prediction model. Random Under-sampling technique was combined with boosting (AdaBoost M2) to enhance the prediction model. Variables with higher predictive power were used for testing and training. A 5-fold cross validation was performed to train and test them on five different subsets of data. Model performance was evaluated using average Area Under the Curve (AUC) using Receiver Operating Curves (ROC) for the 5 test subsets <h3>Results</h3> The significant continuous variables for predicting PTLD were ischemic time, recipient serum creatinine, and presence of B2, DR1,DR2 antigens in recipient serum. Of the categorical variables investigated gender, diabetes in the recipient, ethnicity, CMV status of the donor and induction with azathioprine, OKT3,thymoglobulin or cyclosporine were significant. The AUCs ranged from 0.76 to 0.79 and 0.66 to 0.7 in the testing or validation batch respectively. <h3>Conclusion</h3> This is the first report of using machine learning algorithms to derive a risk prediction model for PTLD. This model has a robust AUC for predicting PTLD at years 1, 3 and 5 posttransplant. The limitations of this study are its retrospective nature and that it needs external validation.

The heart transplant allocation change attenuates but does not eliminate blood group O waitlist outcome disadvantage.

BackgroundPatients with blood group O have historically been disadvantaged in the United Network for Organ Sharing (UNOS) heart transplant allocation system. We sought to determine whether the new UNOS allocation system implemented in 2018 had an impact on waitlist and post‐transplant outcomes among blood groups.MethodsUsing the UNOS database we included all adult patients listed and transplanted with first‐time single‐organ heart transplant between 10/17/15 and 10/1/21. For post‐transplant outcomes, we separately evaluated all adult patients transplanted with the same time‐frame. We used exclusion criteria and censoring to limit biases from changing clinical practices around the allocation change (10/18/2018), and from unequal or inadequate follow‐up. We compared clinical characteristics and outcomes before and after the allocation change among each blood group. Fine‐Gray and Cox regression models were used to estimate the effect of the new allocation system on competing waitlist outcomes‐ transplantation, death‐or‐removal from waitlist‐ and post‐transplant survival, respectively.ResultsOf the 21,565 patients listed for transplantation 14,000 met criteria for waitlist analysis (7,035 in the old system vs. 6,965 in the new), and 7,657 met criteria for post‐transplant analysis (3,519 in the old system vs. 4,138 in the new). Among each blood group, new allocation change was associated with higher transplantation rates lower waitlist days and lower waitlist mortality (except Group AB). However, despite improvements, Group O was still associated with worse waitlist outcomes for each metric compared to non‐O Groups. The new allocation system did not have a significant impact on post‐transplant survival among any blood groups.ConclusionChanges in heart transplant allocation have attenuated but not eliminated blood group O disadvantage in access to donor hearts.

Trends and outcomes following total artificial heart as bridge to transplant from the UNOS database.

Bridge to transplantation (BTT) with a SynCardia Total Artificial Heart (TAH) has been gaining momentum as a therapy for patients with biventricular heart failure. Recent transplant waitlist and posttransplant outcomes with this strategy have not been comprehensively characterized. We reviewed the United Network for Organ Sharing (UNOS) database to examine BTT outcomes for the TAH system since approval. Adult patients listed for heart transplantation in the UNOS system between 2004 and 2020 who underwent BTT therapy with a TAH were included in the study. Trends in utilization of TAH compared with other durable mechanical support strategies were examined. The primary outcome was 1-year survival following heart transplantation following BTT with TAH. Secondary outcomes included waitlist deterioration and risk factors for waitlist or posttransplant mortality. During the study 433 total patients underwent TAH implant as BTT therapy; 236 (54.4%) were listed with the TAH, while the remaining patients were upgraded to TAH support while on the waitlist. Waitlist mortality was 7.4%, with 375 patients (86.6%) ultimately being transplanted. Age, cerebrovascular disease, functional status, and ventilator dependence were risk factors for waitlist mortality. One-year survival following successful BTT was 80%. Risk factors for mortality following BTT included age, body mass index, and underlying diagnosis. Patients undergoing BTT with TAH demonstrate acceptable waitlist survival and good 1-year survival. While utilization initially increased as a BTT therapy, there has been a plateau in relative utilization. Individual patient and transplantation center factors deserve further investigation to determine the ideal population for this therapy.

Use of Impella in Patients Listed for Heart Transplantation.

The new United Network for Organ Sharing (UNOS) policy has resulted in a significantly higher number of temporary mechanical circulatory support device usage such as extracorporeal membrane oxygenation, Impella, and intra-aortic balloon pump due to provision of higher priority with their use while on the waiting list. We aimed to identify Impella use in patients awaiting heart transplantation and temporal changes in its usage. The UNOS database was queried between years 2015 and 2019 for patients aged greater than or equal to 18 years, listed to undergo heart transplantation. A total of 378 patients had Impella support while listed for heart transplantation. Impella use skyrocketed from 2015 (1%) to 2019 (4%, p < 0.01). The most substantial increase in Impella use occurred after the UNOS policy change. The patients listed on Impella support after the policy change had significantly lower waiting time (median 12 days vs. 45 days, p < 0.01). More patients with Impella were directly transplanted (80% vs. 56%, p < 0.01) after the policy change, had significantly lower waitlist mortality (25% vs. 13%, p < 0.01) and fewer converted to a durable support (13% vs. 3%). The translatability (likelihood for receiving organs faster) was significantly improved after the policy change. A multivariable Cox regression model showed that post-transplant survival of Impella patients was not adversely affected after the policy change (hazard ratio = 0.9; p = 0.8). This increase in Impella use represents a substantial change in practice patterns of listing and managing patients on the heart transplant waiting list.

Prolonged Organ Extraction Time Negatively Impacts Kidney Transplantation Outcome.

Main Problem: Following cold aortic flush in a deceased organ donation procedure, kidneys never reach the intended 0–4°C and stay ischemic at around 20°C in the donor’s body until actual surgical retrieval. Therefore, organ extraction time could have a detrimental influence on kidney transplant outcome. Materials and Methods: We analyzed the association between extraction time and kidney transplant outcome in multicenter data of 5,426 transplant procedures from the Dutch Organ Transplantation Registry (NOTR) and 15,849 transplant procedures from the United Network for Organ Sharing (UNOS). Results: Extraction time was grouped per 10-min increment. In the NOTR database, extraction time was independently associated with graft loss [HR 1.027 (1.004–1.050); p = 0.022] and with DGF [OR 1.043 (1.021–1.066); p < 0.005]. An extraction time >80 min was associated with a 27.4% higher hazard rate of graft failure [HR 1.274 (1.080–1.502); p = 0.004] and such kidneys had 43.8% higher odds of developing DGF [OR 1.438, (1.236–1.673); p < 0.005]. In the UNOS database, increasing extraction times in DCD donors were associated with DGF [OR 1.036 (1.016–1.055); p < 0.005]. An extraction time >30 min was associated with 14.5% higher odds of developing DGF [OR 1.145 (1.063–1.233); p < 0.005]. Discussion: Prolonged kidney extraction time negatively influenced graft survival in Dutch donors and increased DGF risk in all deceased donor recipients.