Network For Organ Sharing Database Research Articles

Impact of Age of Heart Transplant Program on Patient Survival and Post-Transplant Outcomes.

The relationship between age of a heart transplant (HT) program and outcomes has not been explored. We performed a retrospective cohort analysis of the United Network for Organ Sharing database of all adult HTs between 2009 and 2019. For each patient, we created a variable that corresponded to program age: new (<5), developing (≥5 but <10) and established (≥10) years. Of 20 997 HTs, 822 were at new, 908 at developing, and 19 267 at established programs. Patients at new programs were significantly more likely to have history of cigarette smoking, ischemic cardiomyopathy, and prior sternotomy. These programs were less likely to accept organs from older donors and those with a history of hypertension or cigarette use. As compared to patients at new programs, transplant patients at established programs had less frequent rates of treated rejection during the index hospitalization (HR 0.43 [95% CI, 0.36-0.53] p<0.001) and at 1 year (HR 0.58 [95% CI, 0.49-0.70], p<0.001), less frequently required pacemaker implantations (HR 0.50 [95% CI, 0.36-0.69], p<0.001), and less frequently required dialysis (HR 0.66 [95% CI, 0.53-0.82], p<0.001). However, there were no significant differences in short- or long-term survival between the groups (log-rank p = 0.24). Patient and donor selection differed between new, developing, and established HT programs but had equivalent survival. New programs had increased likelihood of treated rejection, pacemaker implantation, and need for dialysis. Standardized post-transplant practices may help to minimize this variation and ensure optimal outcomes for all patients.

Cost effectiveness of commercial portable exvivo lung perfusion at a low-volume US lung transplant center.

Portable exvivo lung perfusion during lung transplantation is a resource-intensive technology. In light of its increasing use, we evaluated the cost-effectiveness of exvivo lung perfusion at a low-volume lung transplant center in the USA. Patients listed for lung transplantation (2015-2021) in the United Network for Organ Sharing database were included. Quality-of-life was approximated by Karnofsky Performance Status scores 1-year post-transplant. Total transplantation encounter and 1-year follow-up costs accrued by our academic center for patients listed from 2018 to 2021 were obtained. Cost-effectiveness was calculated by evaluating the number of patients attaining various Karnofsky scores relative to cost. Of the 13 930 adult patients who underwent lung transplant in the United Network for Organ Sharing database, 13 477 (96.7%) used static cold storage and 453 (3.3%) used exvivo lung perfusion, compared to 30/58 (51.7%) and 28/58 (48.3%), respectively, at our center. Compared to static cold storage, median total costs at 1 year were higher for exvivo lung perfusion ($918 000 vs. $516 000; p = 0.007) along with the cost of living 1 year with a Karnofsky functional status of 100 after transplant ($1 290 000 vs. $841 000). In simulated scenarios, each Karnofsky-adjusted life year gained by exvivo lung perfusion was 1.00-1.72 times more expensive. Portable exvivo lung perfusion is not currently cost-effective at a low-volume transplant centers in the USA, being 1.53 times more expensive per Karnofsky-adjusted life year. Improving donor lung and/or recipient biology during exvivo lung perfusion may improve its utility for routine transplantation.

Sex-based Disparities in Liver Transplantation for Hepatocellular Carcinoma and the Impact of the Growing Burden of NASH.

The cause of liver disease is changing, but its impact on liver transplantation (LT) for hepatocellular carcinoma (HCC) in women and men is unclear. We performed a nationwide study to assess the prevalence and posttransplant survival outcomes of the various causes of liver disease in women and men with HCC. Data were obtained from the United Network for Organ Sharing database from 2000 to 2022. Data related to the listing, transplant, waitlist mortality, and posttransplant mortality for HCC were extracted. The proportion of HCC related to the various causes of liver disease among LT candidates and recipients and posttransplant survival were compared between women and men. A total of 51 721 individuals (39 465 men, 12 256 women) with HCC were included. From 2000 to 2022, nonalcoholic steatohepatitis (NASH) was the fastest-growing cause of liver disease among female LT candidates with HCC (P < 0.01), followed by alcohol-associated liver disease. NASH overtook chronic hepatitis C as the leading cause of liver disease in 2020 and 2022 among waitlisted women and men with HCC, respectively. Female patients with HCC spent a significantly longer time on the LT waitlist compared with male patients (β: 8.73; 95% confidence interval [CI], 2.91-14.54). Female patients with HCC from alcohol-associated liver disease also have a lower probability of receiving LT (subdistribution hazard ratio: 0.90; 95% CI, 0.82-0.99). Among transplant recipients with NASH HCC, female sex was associated with lower posttransplant mortality compared with male sex (hazard ratio: 0.79; 95% CI, 0.70-0.89; P < 0.01). Women have a significantly longer waitlist duration compared with men. NASH is now the leading cause of liver disease among both female and male LT candidates and recipients with HCC.

Utilization and outcomes of expanded criteria donors in adults with congenital heart disease

BackgroundUse of donation after circulatory death(DCD) and hepatitis C virus(HCV) positive donors in heart transplantation have increased the donor pool. Given poor waitlist outcomes in the adult congenital heart disease(ACHD) population, we investigated waitlist outcomes associated with willingness to consider DCD and HCV+ offers and post-transplant outcomes following HCV+ and DCD transplantation for these candidates. MethodsUsing the United Network for Organ Sharing database, we identified adult ACHD candidates and recipients listed or transplanted, respectively, between 01/01/2016-09/30/2023 for the HCV analysis and between 12/01/2019-09/30/2023 for the DCD analysis. Among candidates, we compared the cumulative incidence of transplant, with waitlist death/deterioration as a competing risk, by willingness to consider HCV+ and DCD offers. Among recipients of HCV+ (vs. HCV-) and DCD (vs. brain death[DBD]) transplants, we compared perioperative outcomes and post-transplant survival. ResultsOf 1,436 ACHD candidates from 01/01/2016-09/30/2023, 37.0% were willing to consider HCV+ heart offers. Of 886 ACHD candidates from 12/01/2019-09/30/2023, 15.5% were willing to consider DCD offers. On adjusted analysis, willingness to consider HCV+ offers was associated with 84% increased likelihood of transplant, and willingness to consider DCD offers was associated with 56% increased likelihood of transplant. Of 904 transplants between 01/01/2016-09/30/2023, 6.4% utilized HCV+ donors, and of 540 transplants between 12/01/2019-09/30/2023, 6.9% utilized DCD donors. Recipients of HCV+ (vs. HCV-) and DCD (vs. DBD) heart transplants had similar likelihood of perioperative outcomes and 1-year survival. ConclusionsACHD candidates who were willing to consider HCV+ and DCD offers were more likely to be transplanted and had similar post-transplant outcomes compared to recipients of HCV- and DBD organs.

Potential Association of Blood Transfusion in Deceased Donors With Outcomes of Liver Transplantation in the United States

BackgroundDonor blood transfusion may potentially affect transplant outcomes through an inflammatory response, recipient sensitization, or transmission of infection. The aim of this study was to evaluate the association of donor blood transfusion with outcomes of liver transplantation (LT). MethodsFrom January 2004 to December 2022, donor blood transfusion information was available for 113,017 adult recipients of LT in the United Network for Organ Sharing database and was classified into 4 levels of transfusion: no-transfusion (N = 68,130), transfusion of 1-5 units (N = 33,629), 6-10 units (N = 8067), and >10 units (N = 5329). Recipient survival analysis was performed by Kaplan–Meier method and multivariable Cox-hazard model. ResultsAmong this cohort, 40.8% of donors (N = 46,261) received blood transfusion during the index hospitalization. Compared to no-blood transfusion donors, blood transfusion donors were younger (median age 37 versus 46 y P < 0.001) and were more brain death donors (94.5% versus 92.1%, P < 0.001). An increased risk of rejection at 6-mo (transfusion 10.3% versus no-transfusion 9.9%, P = 0.055) and 1 y (transfusion 12.5% versus no-transfusion 11.9%, P = 0.0036) post-LT was noted in this cohort. Multivariable Cox-hazard model showed blood transfusion was associated with increased 1-y mortality (transfusion 1.07; 95% CI 1.02-1.12, P = 0.007) and graft failure (transfusion 1.09; 95% CI 1.04-1.13, P < 0.001). ConclusionsDonor blood transfusion was associated with an increased risk of rejection at 6 mo and 1 y among LT recipients and worse post-transplant graft and overall survival. Additional information regarding donor blood transfusion, along with other known factors, may be considered when deciding the optimization of overall immune suppression in LT recipients to decrease the risk of delayed rejection.

Incidence and Risk Factors for Stroke After Combined Heart-Kidney and Heart-Liver Transplantation.

While stroke is a well-recognized complication of isolated heart transplantation, stroke in patients undergoing simultaneous heart-liver (HLT) and heart-kidney transplantation (HKT) has not been explored. This study assessed postoperative stroke incidence, risk factors, and outcomes in HLT and HKT compared with isolated heart transplant. The United Network for Organ Sharing database was queried for adult patients undergoing HLT, HKT, and isolated heart transplants between 1994 and 2022. Patients were stratified by presence of in-hospital stroke after transplant. Post-transplant survival at 1-year was assessed using Kaplan-Meier analysis and log-rank tests. Separate multivariable logistic regression models were constructed to identify risk factors for stroke after HKT and HLT. Of 2326 HKT recipients, 85 experienced stroke, and of 442 HLT recipients, 19 experienced stroke. Stroke was more common after HKT and HLT than after an isolated heart transplant (3.7% vs. 4.3% vs. 2.9%, p=0.01). One-year post-transplant survival was lower in those with stroke among both HKT recipients (64.5% vs. 88.7%, p(log-rank)<0.001) and HLT recipients (43.8% vs. 87.4%, p(log-rank)<0.001. Pre-transplant pVAD, prior stroke, postoperative dialysis, diabetes, prior cardiac surgery, and heart cold ischemic time were independent risk factors for stroke after HKT, after adjusting for age, sex, and need for blood transfusion on the waitlist. For HLT, postoperative dialysis was a significant risk factor. Stroke is more common after HKT and HLT than after isolated heart transplant, and results in poor survival. Independent risk factors for stroke include pre-transplant percutaneous VAD (HKT) and postoperative dialysis (HKT and HLT).

Characterizing Adaptive Changes and Patient Survival After 2018 Donor Allocation Restructuring: A UNOS Database Analysis.

We sought to characterize adaptive changes to the revised United Network for Organ Sharing donor heart allocation policy and estimate long-term survival trends for heart transplant (HTx) recipients. Patients listed for HTx between October 17, 2013 and September 30, 2021 were identified from the United Network for Organ Sharing database, and stratified into pre- and postpolicy revision groups. Subanalyses were performed to examine trends in device utilization for extracorporeal membranous oxygenation (ECMO), durable left ventricular assist device (LVAD), intra-aortic balloon pump (IABP), microaxial support (Impella), and no mechanical circulatory support (non-MCS). Survival data post-HTx were fitted to parametric distributions and extrapolated to 5 years. We identified 27,523 HTx waitlist candidates during the study period, most of whom (n = 16,376) were waitlisted in the prepolicy change period. Overall, 19,554 patients underwent HTx during the study period (pre: 12,037 and post: 7517). Listings increased after the policy change for ECMO ( P < 0.01), Impella ( P < 0.01), and IABP ( P < 0.01) patients. Listings for LVAD ( P < 0.01) and non-MCS ( P < 0.01) patients decreased. HTx increased for ECMO ( P < 0.01), Impella ( P < 0.01), and IABP ( P < 0.01) patients after the policy change and decreased for LVAD ( P < 0.01) and non-MCS ( P < 0.01) patients. Waitlist survival increased for the overall ( P < 0.01), ECMO ( P < 0.01), IABP ( P < 0.01), and non-MCS ( P < 0.01) groups. Waitlist survival did not differ for the LVAD ( P = 0.8) and Impella ( P = 0.1) groups. Post-transplant survival decreased for the overall ( P < 0.01), LVAD ( P < 0.01), and non-MCS ( P < 0.01) populations. Allocation policy revisions have contributed to greater utilization of ECMO, Impella, and IABP, decreased utilization of LVADs and non-MCS, increased waitlist survival, and decreased post-HTx survival.

Right ventricular sizing and pulmonary vascular resistance: How much mass do you need?

ObjectiveRight ventricular (RV) donor-recipient sizing has been demonstrated to be a sensitive predictor for mortality after heart transplantation. We sought to understand the relationship between donor-recipient RV mass (RVM) ratio and pulmonary vascular resistance (PVR) on outcomes after heart transplantation. MethodsAdult heart transplant recipients from the United Network for Organ Sharing database were included (N = 42,594). The influence of RVM ratio and PVR on 1-year mortality was assessed by logistic regression after multivariable adjustment. ResultsAmong transplant recipients, median PVR was 2.4 Wood units (WU) (range, 1.7-3.3 WU) and median RVM ratio was 1.2 (1.0-1.3). Without considering PVR, RVM ratio was highly associated with postoperative dialysis (odds ratio [OR], 0.49; P < .001) and 1-year mortality (OR, 0.64; P < .001). Without considering RVM ratio, PVR was highly associated with 1-year mortality (OR, 1.05; P < .001), but not postoperative dialysis (OR, 0.98; P = .156). When considering both RVM ratio and PVR, the risk associated with each remained significant, but PVR did not modify the effect of RVM ratio on 1-year mortality (RVM ratio × PVR: OR, 0.99; P = .858). To maintain a consistent predicted 1-year mortality, RVM ratio would need to increase by 0.12 for each WU increase in PVR. Secondary analyses found that a 1 WU change in PVR was associated with an 11% increase in mortality risk in RVM ratio mismatched patients (RVM ratio < 1; P = .001), but only a 5% increase in RVM ratio matched patients (RVM ratio ≥ 1; P = .003). ConclusionsRVM ratio and recipient PVR are independent predictors of 1-year mortality. Still, a larger RV mass may be utilized to mediate the effects of an elevated PVR.

The suggestion of mitigating disparity in the liver transplantation field among ABO blood type

Medical literature highlights differences in liver transplantation (LT) waitlist experiences among ABO blood types. Type AB candidates reportedly have higher LT rates and reduced mortality. Despite liver offering guidelines, ABO disparities persist. This study examines LT access discrepancies among blood types, focusing on type AB, and seeks equitable strategies. Using the United Network for Organ Sharing database (2003-2022), 170 276 waitlist candidates were retrospectively analyzed. Dual predictive analyses (LT opportunity and survival studies) evaluated 1-year recipient pool survival, considering waitlist and post-LT survival, alongside anticipated allocation value per recipient, under 6 scenarios. Of the cohort, 97 670 patients (57.2%) underwent LT. Type AB recipients had the highest LT rate (73.7% vs 55.2% for O), shortest median waiting time (90 vs 198 days for A), and lowest waitlist mortality (12.9% vs 23.9% for O), with the lowest median model for end-stage liver disease-sodium (MELD-Na) score (20 vs 25 for A/O). The LT opportunity study revealed that reallocating type A (or A and O) donors originally for AB recipients to A recipients yielded the greatest reduction in disparities in anticipated value per recipient, from 0.19 (before modification) to 0.08. Meanwhile, the survival study showed that ABO-identical LTs reduced disparity the most (3.5% to 2.8%). Sensitivity analysis confirmed these findings were specific to the MELD-Na score < 30 population, indicating current LT allocation may favor certain blood types. Prioritizing ABO-identical LTs for MELD-Na score < 30 recipients could ensure uniform survival outcomes and mitigate disparities.

The impact of the OPTN policy change on patients with a durable left ventricular assist device and chronic kidney disease: Analysis of the UNOS database.

The Organ Procurement and Transplantation Network (OPTN) implemented modifications in 2018 to the adult heart transplant allocation system to better stratify the most medically urgent transplant candidates. We evaluated the impact of these changes on patients supported by a durable left ventricular assist device (LVAD) with chronic kidney disease (CKD). To evaluate the impact of the OPTN policy change on patients supported by durable left ventricular assist devices (LVAD) with chronic kidney disease (CKD). We performed an analysis of patients from the United Network of Organ Sharing Database supported by durable LVAD listed for a heart transplant (HT) between October 17, 2016 and September 30, 2021. Patients were divided into two groups: pre- and postpolicy, depending on whether they were listed on or prior to October 17, 2018. Patients who were on dialysis prior to surgery or discharge were excluded from the analysis. Patients with simultaneous heart and kidney transplants were excluded. Patients who were listed for transplant prepolicy change but transplanted postpolicy change were excluded. This cohort was then subdivided into degrees of CKD based on estimated glomerular filtration rate (eGFR), which resulted in 678 patients (23.7%) in Stage 1 (GFR ≥89.499) (Prepolicy: 345, Postpolicy: 333), 1233 (43.1%) in Stage 2 (89.499 > GFR ≥ 59.499) (Prepolicy: 618, Postpolicy: 615), 613 (21.4%) in Stage 3a (59.499 > GFR ≥ 44.499) (Prepolicy: 291, Postpolicy: 322), 294 (10.3%) in Stage 3b (44.499 > GFR ≥ 29.499) (Prepolicy: 143, Postpolicy: 151), 36 (1.3%) in Stage 4 (29.499 > GFR ≥ 15) (Prepolicy: 21, Postpolicy: 15), and 9 (0.3%) in Stage 5 (15 > GFR) (Prepolicy: 4, Postpolicy: 5). The primary outcome was 1-year and 2-year post-HT survival. There were 2863 patients who met the study criteria (1422 prepolicy, 1441 postpolicy). Overall survival, regardless of CKD stage, was lower following the policy change (p < 0.01). There was a similar risk of primary graft failure (PGF) in the pre- and postpolicy period (1.8% vs. 1.2%, p = 0.26). 1-year overall survival was 93% (91, 94) and 89% (87, 91) in the pre- and postpolicy periods, respectively. 2-year overall survival was 89% (88, 91) and 85% (82, 87) in the pre- and postpolicy periods, respectively. For CKD Stages 1, 2, 3a, 3b, 4, and 5, 1 -year survival was 93% (91, 95), 92% (90,93), 89% (86, 91), 89% (86, 93), 80% (68, 94), and 100% (100, 100), respectively. For CKD Stages 1, 2, 3a, 3b, 4, and 5, 2-year survival was 91% (88, 93), 88% (86, 90), 84% (81, 88), 84% (80, 89), 73% (59, 90), and 100% (100, 100), respectively. Patients with CKD 1 and 2 had better survival compared to those with CKD 3 (p < 0.01) and CKD 4 and 5 (p = 0.03) in the pre- and postpolicy periods. Patients with CKD 3 did not have a survival advantage over those with CKD 4 and 5 (p = 0.25). On cox regression analysis, advancing degrees of CKD were associated with an increased risk of mortality. Patients with LVAD support had decreased overall survival after the OPTN policy change. Patients with more advanced CKD had lower survival than patients without advanced CKD, though they were not impacted by the OPTN policy change.

Impact of Left Ventricular Unloading on Outcome of Heart Transplant Bridging With Extracorporeal Membrane Oxygenation Support in New Allocation Policy.

The new heart allocation policy places veno-arterial extracorporeal membrane oxygenation (VA-ECMO)-supported heart transplant (HT) candidates at the highest priority status. Despite increasing evidence supporting left ventricular (LV) unloading during VA-ECMO, the effect of LV unloading on transplant outcomes following bridging to HT with VA-ECMO remains unknown. From October 18, 2018 to March 21, 2023, 624 patients on VA-ECMO at the time of HT were identified in the United Network for Organ Sharing database and were divided into 2 groups: VA-ECMO alone (N=384) versus VA-ECMO with LV unloading (N=240). Subanalysis was performed in the LV unloading group: Impella (N=106) versus intra-aortic balloon pump (N=134). Recipient age was younger in the VA-ECMO alone group (48 versus 53 years, P=0.018), as was donor age (VA-ECMO alone, 29 years versus LV unloading, 32 years, P=0.041). One-year survival was comparable between groups (VA-ECMO alone, 88.0±1.8% versus LV unloading, 90.4±2.1%; P=0.92). Multivariable Cox hazard model showed LV unloading was not associated with posttransplant mortality after HT (hazard ratio, 0.92; P=0.70). Different LV unloading methods had similar 1-year survival (intra-aortic balloon pump, 89.2±3.0% versus Impella, 92.4±2.8%; P=0.65). Posttransplant survival was comparable between different Impella versions (Impella 2.5, versus Impella CP, versus Impella 5.0, versus Impella 5.5). Under the current allocation policy, LV unloading did not impact waitlist outcome and posttransplant survival in patients bridged to HT with VA-ECMO, nor did mode of LV unloading. This highlights the importance of a tailored approach in HT candidates on VA-ECMO, where routine LV unloading may not be universally necessary.

Changes in Donor Utilization and Outcomes for Patients Bridged With Durable Left Ventricular Assist Device.

We studied the impact of the 2018 heart allocation policy change on donor characteristics and posttransplant outcomes of left ventricular assist device (LVAD)-bridged heart transplant (HT) recipients. Left ventricular assist device-bridged adult HT recipients from October 2014 to October 2022 in the United Network for Organ Sharing database were categorized into old allocation policy (OAP) and new allocation policy (NAP) cohorts. Baseline characteristics, posttransplant outcomes, and subgroup analyses of unstable and stable LVAD-bridged recipients were assessed. The study included 7,384 HT recipients; 4,345 (58.8%) were transplanted in the OAP era and 3,039 (41.2%) in the NAP era. Old allocation policy recipients were most frequently status 1A at transplantation (71.1%), whereas NAP recipients were most frequently status 3 (40.0%), and status 4 (31.9%). Median donor sequence number (DSN) was higher in the NAP versus OAP era (9 vs. 3, p < 0.001). On multivariable analysis, NAP recipients had 20% higher 1 year mortality compared to OAP (adjusted hazard ratio [aHR] = 1.20 [95% confidence interval {CI}: 1.04-1.40], p = 0.01). Status 1 or 2 recipients had 28% higher 1 year mortality compared to status 1A (aHR = 1.28 [95% CI: 1.01-1.63], p = 0.04). Status 1 and 2 LVAD-supported recipients had higher mortality following the 2018 allocation change, indicating the need for closer surveillance of LVAD-bridged patients who may decompensate on the waitlist.

A Decade of Liver Transplantation in the United States: Drivers of Discard and Underutilization.

Organ shortage remains a major challenge for the field of transplantation. Maximizing utilization and minimizing discard of available organs is crucial to reduce waitlist times. Our aim was to investigate the landscape of liver recovery, discard over the past decade in the United States, and identify areas to reduce organ discard. This study used the Scientific Registry of Transplant Recipients United Network for Organ Sharing database to analyze the rates and associated reasons of discarded organs from 2010 to 2021. All deceased donors were evaluated, and data were analyzed by organ type, year, and region. Organ disposition was analyzed by year and region. Donor demographics and liver biopsy data were also analyzed. The volume of liver transplantation increased steadily, with a 44% increase from 2010 to 2021. Donation after circulatory death transplantation increased by 239%, comprising 10.6% of transplants in 2021, yet discard rates remained high at 30% for this donor subset. For all donor types, the liver discard rate has remained stable around 10% despite a 74% increase in available donors. Seventy percent of liver discards were attributed to organ factors, with biopsy findings accounting for 40% of all discards. Of livers that were biopsied, 70% had macrosteatosis of <30%. Analysis of trends in transplantation and discard allow for identifying areas of underutilization. Donation after circulatory death livers have expanded the pool of transplanted livers but remain discarded at high rates. Significant differences remain in discard rates between geographic regions. We identify several areas to lower the discard rates. The expanding role of machine perfusion may allow for utilization of previously discarded organs.

Analysis of UNOS: Pediatric Heart Transplantation Over 36 Years and Contemporary Volume-Outcome Relationship

BackgroundThis study examines 36 years of national pediatric heart transplantation data to (1) identify trends in transplant volume, centers, and 1-year graft survival and (2) assess how center transplant volume affects outcomes over a contemporary 11-year period. MethodsStudy investigators utilized the United Network for Organ Sharing database and performed a retrospective review of pediatric patients (aged <18 years) who underwent heart transplantation between January 1, 1987 and December 31, 2022, inclusive. Trend analyses included the whole cohort, whereas volume-outcome analyses included a contemporary cohort (January 1, 2012 through December 31, 2022) to account for the temporal changes observed in transplant survival. Highest-volume centers were defined by the number of heart transplantations performed per center per year. ResultsOver 36 years, 11,828 pediatric heart transplantations were performed. Transplant volume steadily rose, the number of centers remained stable, and 1-year graft survival improved significantly. In the contemporary era (2012-2022), 89 centers conducted 4959 pediatric heart transplantations. The top 15% high-volume centers (13 centers) accounted for 48.3% (n = 2393) of transplantations, with an average of 16.7 ± 3.8 transplantations per center annually, compared with 3.9 ± 3.1 for lower-volume centers (P < .001). Despite performing transplantations in higher-risk patients, high-volume centers achieved similar postoperative outcomes and improved long-term survival compared with low-volume centers. ConclusionsAlthough the number of US pediatric heart transplant centers has remained stable, pediatric heart transplant volume has steadily increased, as has 1-year graft survival. In a contemporary cohort, the top 15th percentile highest-volume centers accounted for 48.3% of US pediatric heart transplants and performed transplantations in higher-risk patients with similar postoperative outcomes and improved longitudinal survival.

Live-donor kidney transplant outcome prediction (L-TOP) using artificial intelligence.

Outcome prediction for live-donor kidney transplantation improves clinical and patient decisions and donor selection. However, the concurrently used models are of limited discriminative or calibration power and there is a critical need to improve the selection process. We aimed to assess the value of various artificial intelligence (AI) algorithms to improve the risk stratification index. We evaluated pre-transplant variables among 66914 live-donor kidney transplants (performed between 01/12/2007-01/06/2021) from the United Network of Organ Sharing database, randomized into training (80%) and test (20%) sets. The primary outcome measure was death-censored graft survival. We tested four machine learning models for discrimination (time-dependent concordance index, CTD, and area under the ROC curve) and calibration (integrated Brier score, IBS). We used decision curve analysis to assess the potential clinical utility. Among the models, the deep Cox mixture model showed the best discriminative performance (AUC=0.70, 0.68, and 0.68 at 5, 10, and 13 years post-transplant, respectively). CTD reached 0.70, 0.67, and 0.66 at 5, 10, and 13 years post-transplant. The IBS score was 0.09, indicating good calibration. In comparison, applying the Living Kidney Donor Profile Index (LKDPI) on the same cohort produced a CTD of 0.56 and an AUC of 0.55-0.58 only. Decision curve analysis showed an additional net benefit compared to the LKDPI, 'Treat all' and 'Treat None' approaches. Our AI-based deep Cox mixture model, termed Live-Donor Kidney Transplant Outcome Prediction outperforms existing prediction models, including the LKDPI, with the potential to improve decisions for optimum live donor selection by ranking potential transplant pairs based on graft survival. This model could be adopted to improve the outcomes of paired exchange programs.

Enhancing the usability of older DCD donors through strategic approaches in liver transplantation in the United States.

The use of older donors after circulatory death (DCD) for liver transplantation (LT) has increased over the past decade. This study examined whether outcomes of LT using older DCD (≥50y) have improved with advancements in surgical/perioperative care and normothermic machine perfusion (NMP) technology. A total of 7602 DCD LT cases from the United Network for Organ Sharing database (2003-2022) were reviewed. The impact of older DCD donors on graft survival was assessed using the Kaplan-Meier and HR analyses. In all, 1447 LT cases (19.0%) involved older DCD donors. Although there was a decrease in their use from 2003 to 2014, a resurgence was noted after 2015 and reached 21.9% of all LTs in the last 4 years (2019-2022). Initially, 90-day and 1-year graft survivals for older DCDs were worse than younger DCDs, but this difference decreased over time and there was no statistical difference after 2015. Similarly, HRs for graft loss in older DCD have recently become insignificant. In older DCD LT, NMP usage has increased recently, especially in cases with extended donor-recipient distances, while the median time from asystole to aortic cross-clamp has decreased. Multivariable Cox regression analyses revealed that in the early phase, asystole to cross-clamp time had the highest HR for graft loss in older DCD LT without NMP, while in the later phases, the cold ischemic time (>5.5h) was a significant predictor. LT outcomes using older DCD donors have become comparable to those from young DCD donors, with recent HRs for graft loss becoming insignificant. The strategic approach in the recent period could mitigate risks, including managing cold ischemic time (≤5.5h), reducing asystole to cross-clamp time, and adopting NMP for longer distances. Optimal use of older DCD donors may alleviate the donor shortage.

The Impact of Local Programmatic Decisions on Outcomes in Transplant-Listed Adults With Congenital Heart Disease

We investigated variables impacting waitlist time and negative waitlist outcomes in adult congenital heart disease (ACHD) orthotopic heart transplant (OHT) candidates following the 2018 allocation change. Adult OHT candidates listed between 10/18/2018-12/31/2022 in the United Network for Organ Sharing database were categorized as ACHD vs. non-ACHD. Waitlist time and time to upgrade for those upgraded into status 1-3 were compared using rank-sum tests. Death/delisting for deterioration was assessed using Fine-Gray sub-distribution hazard ratios (SHRs). Of 15,424 OHT candidates, 589 (3.8%) were ACHD. ACHD vs. non-ACHD candidates had less urgent status at initial listing (4.2% vs. 4.7% listed at status 1; 17.2% vs. 23.7% listed at status 2, p<0.001), but not final listing (5.9% vs. 7.6% final status 1; 35.6% vs. 36.8% final status 2, p<0.001). ACHD vs. non-ACHD candidates upgraded into status 1 (65.0 vs. 30.0 days, p=0.09) and status 2 (113.0 vs. 64.0 days, p=0.003) spent longer on the waitlist. ACHD vs. non-ACHD candidates spent longer waiting for an upgrade into status 1 (51.4 vs. 17.6 days, p=0.027) and status 2 (76.7 vs. 34.7 days, p=0.003). Once upgraded, there was no difference between groups in waitlist time as status 1 (9.7 vs. 5.5 days, p=0.66). ACHD vs. non-ACHD candidates with a final status of 1 (20.0% vs. 8.6%; SHR 2.47 [95%CI=1.19-5.16], p=0.02) and 2 (8.9% vs. 2.3%; SHR 3.59 [95%CI=2.18-5.91], p<0.001) experienced higher death/deterioration. ACHD candidates have longer waitlist times, lower priority status at initial listing, wait longer for upgrade, and have higher mortality at the same final status as non-ACHD candidates, suggesting that they are being upgraded too late.

National Trends in Utilization of Normothermic Machine Perfusion in DCD Liver Transplantation.

In liver transplantation, advances in ex situ normothermic machine perfusion (NMP) have improved outcomes compared with traditional static cold storage (SCS) in donation after circulatory death (DCD) organs. We aimed to characterize trends in the utilization of NMP versus SCS in DCD liver transplantation in the United States. This retrospective cohort study used data from the United Network for Organ Sharing database to identify recipient-donor adult liver transplant pairs from DCD donors from January 2016 to June 2022. Utilization of NMP and changes in donor risk index (DRI) and components between NMP and SCS were assessed across transplant year eras (2016-2018, 2019-2020, and 2021-2022). Statistical comparisons were made using the Kruskal-Wallis test or the chi-square test. A total of 3937 SCS and 127 NMP DCD donor transplants were included. Utilization of NMP ranged from ~0.4% to 3.5% from 2016 to 2021 and rose significantly to 11.2% in early 2022. Across transplant eras, median DRI increased significantly for SCS and NMP, but the magnitude of the increase was larger for NMP. With NMP DCDs, there were significant increases in median donor age, national share proportion, and "cold ischemic time" over time. Finally, there was a shift toward including higher DRI donors and higher model for end-stage liver disease score transplant recipients with NMP in later transplant eras. In recent years, NMP utilization has increased and expanded to donors with higher DRI and recipients with higher model for end-stage liver disease score at transplant, suggesting increasing familiarity and risk tolerance with NMP technology. As NMP remains a relatively new technique, ongoing study of patient outcomes, organ allocation practices, and utilization patterns is critical.

Indications and outcomes of liver transplantation for liver tumors in the United States

BackgroundWhile hepatocellular carcinoma (HCC) remains the leading cause of liver transplant (LT) for liver tumors, indications have broadened over the years. Data regarding patient characteristics and outcomes of LT for liver tumors are limited. MethodsFrom Jan-2002 to March-2022, 14,406 LT recipients for various liver tumors were identified in United Network for Organ Sharing database. Overall post-transplant survival analysis was performed with Kaplan-Meier method and multivariable Cox proportional-hazards model. ResultsDuring the study period, indications for LT for various hepatic tumors were HCC (88.5 %), benign tumors (5.1 %), cholangiocarcinoma (3.9 %), angiosarcoma (0.7 %), bile duct cancer (0.7 %), secondary tumors (0.5 %) and others (0.7 %). Compared to non-HCC, LT recipients for HCC were older (median age 61 vs 54 years, P < 0.001), more often male (77% vs 48 %, P < 0.001), more often Hispanic (16% vs 8.0 %), had higher BMI (28.2 vs 25.3, P < 0.001) and higher prevalence of Hepatitis C (53% vs 3.9 %, P < 0.001). Donor characteristics across various groups were similar. One-year survival in LT recipients of HCC was higher (HCC: 91.7% vs. non-HCC: 90.3 %) with adjusted Hazard Ratio (aHR) of 0.87; 95 % CI 0.77–0.99, P = 0.033 in a multivariable Cox regression analysis. Compared to HCC, survival outcomes were worse in cholangiocarcinoma (aHR 1.70; 95 %CI 1.43–2.01, P < 0.001), bile duct cancer (aHR 3.03; 95 %CI 2.12–4.33, P < 0.001), secondary tumors including colon cancer and neuroendocrine tumors (aHR 1.88; 95 % CI 1.24–2.85, P = 0.003), with best survival in patients with benign tumors (aHR 0.57; 95 %CI 0.46–0.70, P < 0.001). ConclusionsLT is performed for various liver tumors with variable outcomes among these primary indications.

(913) - Does Ex Vivo Lung Perfusion Mitigate the Detrimental Effects of Primary Graft Dysfunction? A Propensity Matched Analysis of the United Network for Organ Sharing Database

(913) - Does Ex Vivo Lung Perfusion Mitigate the Detrimental Effects of Primary Graft Dysfunction? A Propensity Matched Analysis of the United Network for Organ Sharing Database