Analysis of Liver Offers to Pediatric Candidates on the Transplant Wait List

Variability in pediatric and neonatal organ offering, acceptance and utilization: a survey of Canadian pediatric transplant programs and organ donation organizations

Introduction

Solid organ transplantation in children is a lifesaving therapy, however, pediatric organ donation rates remain suboptimal.

Methods

We conducted a cross-sectional survey of Canadian organ donation organizations (ODOs) and pediatric transplant programs (TPs), aiming to describe policies and practices for pediatric organ allocation, acceptance, and utilization in Canada.

Results

Response rates were 82% and 83% respectively for ODOs and transplant programs comprising 7 kidney, 3 heart, 2 lung, 2 liver and 1 intestine programs. All 9 ODOs reported offering pediatric organs following death by neurological criteria (DNC), while 8 reported offering organs following death by circulatory criteria (DCC) for some organs. Variability was found across ODOs and TPs. There was little agreement on both absolute and organ-specific donor exclusion criteria between ODOs. There was further disagreement in organ specific acceptance criteria between ODOs and TPs and between TPs themselves. Notably, despite the development of pediatric donation after DCC guidelines, organs from DCC donors are excluded by many ODOs and TPs.

Discussion

Further variability in pediatric specific training, policies, and allocation guidelines are also documented. Significant areas for improvement in standardization in organ acceptance, offering, and allocation in pediatric donation and transplantation across Canada were identified.

Pushing the Limits of In Situ Split Liver Procurement to Overcome Donor Distance and Graft Size Challenges for 8-Week-Old Pediatric Recipient

BACKGROUND

Pediatric liver transplantation for small recipients presents significant challenges, particularly in securing suitably sized donor organs. This case report illustrates the feasibility of performing an in situ split procurement in an 18.5-kg toddler, the smallest recorded case in the OPTN database to date, for a critically ill 8-week-old infant recipient.

CASE PRESENTATION

An 8-week-old infant with severe hepatitis of unknown etiology was urgently listed as Status 1A. An organ offer from a 3.5-year-old donor, requiring a reduction procedure, became available 1939 nautical miles away. Instead of a back-table reduction procedure, we performed an in situ split to reduce cold ischemic time given the distance. The recipient surgery was started ahead of the organ's arrival, and the recipient was ready for graft implantation upon the organ's arrival, resulting in a total of 510 min of cold ischemic time. Post-operatively, the graft did not show signs of significant injury or dysfunction, which expedited recovery from her other medical conditions.

CONCLUSIONS

In situ split liver procurement is an invaluable tool for pediatric centers as it effectively provides more graft options for pediatric patients on the waitlist. Additionally, in situ split can offer significant benefits in optimizing recipient surgery, especially when the donor is located at an extreme distance. Despite these benefits, in situ split is not currently widely utilized across transplant centers. Addressing the logistical challenges associated with this technique is crucial for broader implementation and improved patient outcomes.

Utilization of older deceased donors for pediatric liver transplant may negatively impact long-term survival

BACKGROUND

Multiple adult studies have investigated the role of older donors (ODs) in expanding the donor pool. However, the impact of donor age on pediatric liver transplantation (LT) has not been fully elucidated.

METHODS

UNOS database was used to identify pediatric (≤18 years) LTs performed in the United States during 2002-22. Donors ≥40 years at donation were classified as older donors (ODs). Propensity analysis was performed with 1:1 matching for potentially confounding variables.

RESULTS

A total of 10,024 pediatric liver transplantation (PLT) patients met inclusion criteria; 669 received liver grafts from ODs. Candidates receiving OD liver grafts were more likely to be transplanted for acute liver failure, have higher Model End-Stage Liver Disease/Pediatric End-Stage Liver Disease (MELD/PELD) scores at LT, listed as Status 1/1A at LT, and be in the intensive care unit (ICU) at time of LT (all p < 0.001). Kaplan-Meier (KM) analyses showed that recipients of OD grafts had worse patient and graft survival (p < 0.001) compared to recipients of younger donor (YD) grafts. KM analyses performed on candidates matched for acuity at LT revealed inferior patient and graft survival in recipients of deceased donor grafts (p < 0.001), but not living donor grafts (p > 0.1) from ODs. Cox regression analysis demonstrated that living donor LT, diagnosis of biliary atresia and first liver transplant were favorable predictors of recipient outcomes, whereas ICU stay before LT and transplantation during 2002-12 were unfavorable.

CONCLUSION

Livers from ODs were used for candidates with higher acuity. Pediatric recipients of livers from ODs had worse outcome compared to YDs; however, living donor LT from ODs had the least negative impact on recipient outcomes.

Tailoring allocation policies and improving access to paediatric liver transplantation over a 16-year period

BACKGROUND & AIMS

Mortality on the paediatric liver transplantation (pLT) waiting list (WL) is still an issue. We analysed the Italian pLT WL to evaluate the intention-to-treat (ITT) success rate and to identify factors influencing success.

METHODS

All children (<18 years) listed for pLT in Italy between 2002-2018 were included (Era 1 [2002-2007]: centre-based allocation; Era 2 [2008-2014]: national allocation; Era 3 [2015-2018]: national allocation+mandatory-split policy).

RESULTS

A total of 1,424 patients (median age: 2.0 [IQR 1.0-9.0] years; median weight: 12.0 kg [IQR 7-27]) were listed for pLT. Median WL time was 2 days (IQR 1-5) for Status 1 and 44 days (IQR 15-120) for non-Status 1 patients; 1,302 children (91.4%) were transplanted (67.3% with split grafts), while 50 children (3.5%) dropped off the WL (2.5% death, 1.0% clinical deterioration). Predictive factors for receiving LT included Status 1 (hazard ratio [HR] 1.66, p = 0.001), Status 1B (HR 1.96, p = 0.016), Status 2A (HR 2.15, p = 0.024) and each 1-point increase in PELD/MELD score. Children with recipient's weight >25 kg, blood group O or awaiting pLT combined with other organs had less chance of being transplanted. ITT patient survival rates were 90.5% at 1 year and 87.5% at 5 years, remaining stable across eras. Risk factors for ITT survival were re-transplantation (HR 5.83, p <0.001), Status 1 (HR 2.28, p = 0.006), Status 1B (HR 2.90, p = 0.014), Status 2A (HR 9.12, p <0.001), recipient weight <6 kg (HR 4.53, p <0.001) and low-volume activity (HR 4.38, p = 0.001).

CONCLUSIONS

In Italy, continuous adaption of paediatric organ allocation policies via the introduction of national allocation, paediatric prioritisation rules and a mandatory-split policy have helped maximise the use of donors for paediatric candidates and to minimise WL mortality without compromising outcomes.

IMPACT AND IMPLICATIONS

Globally, paediatric liver transplant candidates still suffer from high mortality. Over recent decades, the continuous adaption of organ allocation policies in Italy has led to excellent outcomes for children awaiting liver transplantation. The mortality rate of paediatric liver transplant candidates has been minimised to almost zero, mainly using grafts from deceased donors. Paediatric prioritisation rules, national organ exchange organisation and a mandatory-split liver policy have resulted in a unique allocation model for paediatric liver transplant candidates and represent a landmark for the paediatric transplant community.

Technical Variant Liver Transplant Utilization for Pediatric Recipients: Equal Graft Survival to Whole Liver Transplants and Promotion of Timely Transplantation Only When Performed at High-volume Centers

BACKGROUND

Technical variant liver transplantation (TVLT) is a strategy to mitigate persistent pediatric waitlist mortality in the United States, although its implementation remains stagnant. This study investigated the relationship between TVLT utilization, transplant center volume, and graft survival.

METHODS

Pediatric liver transplant recipients from 2010 to 2020 (n = 5208) were analyzed using the Scientific Registry of Transplant Recipients database. Transplant centers were categorized according to the average number of pediatric liver transplants performed per year (high-volume, ≥5; low-volume, <5). Graft survival rates were compared using Kaplan-Meier curves and log-rank tests. Cox proportional hazards models were used to identify predictors of graft failure.

RESULTS

High-volume centers demonstrated equivalent whole liver transplant and TVLT graft survival ( P = 0.057) and significantly improved TVLT graft survival compared with low-volume centers ( P < 0.001). Transplantation at a low-volume center was significantly associated with graft failure (adjusted hazard ratio, 1.6; 95% confidence interval, 1.14-2.24; P = 0.007 in patients <12 y old and 1.8; 95% confidence interval, 1.13-2.87; P = 0.013 in patients ≥12 y old). A subset of high-volume centers with a significantly higher rate of TVLT use demonstrated a 23% reduction in waitlist mortality.

CONCLUSIONS

Prompt transplantation with increased TVLT utilization at high-volume centers may reduce pediatric waitlist mortality without compromising graft survival.

Three-dimensional Liver Model Application for Liver Transplantation

BACKGROUND

Children are removed from the liver transplant waitlist because of death or progressive illness. Size mismatch accounts for 30% of organ refusal. This study aimed to demonstrate that 3-dimensional (3D) technology is a feasible and accurate adjunct to organ allocation and living donor selection process.

METHODS

This prospective multicenter study included pediatric liver transplant candidates and living donors from January 2020 to February 2023. Patient-specific, 3D-printed liver models were used for anatomic planning, real-time evaluation during organ procurement, and surgical navigation. The primary outcome was to determine model accuracy. The secondary outcome was to determine the impact of outcomes in living donor hepatectomy. Study groups were analyzed using propensity score matching with a retrospective cohort.

RESULTS

Twenty-eight recipients were included. The median percentage error was -0.6% for 3D models and had the highest correlation to the actual liver explant (Pearson's R = 0.96, P < 0.001) compared with other volume calculation methods. Patient and graft survival were comparable. From 41 living donors, the median percentage error of the allograft was 12.4%. The donor-matched study group had lower central line utilization (21.4% versus 75%, P = 0.045), shorter length of stay (4 versus 7 d, P = 0.003), and lower mean comprehensive complication index (3 versus 21, P = 0.014).

CONCLUSIONS

Three-dimensional volume is highly correlated with actual liver explant volume and may vary across different allografts for living donation. The addition of 3D-printed liver models during the transplant evaluation and organ procurement process is a feasible and safe adjunct to the perioperative decision-making process.

Improving outcomes of in situ split liver transplantation in Italy over the last 25 years

BACKGROUND & AIMS

Split liver transplant(ation) (SLT) is still considered a challenging procedure that is by no means widely accepted. We aimed to present data on 25-year trends in SLT in Italy, and to investigate if, and to what extent, outcomes have improved nationwide during this time.

METHODS

The study included all consecutive SLTs performed from May 1993 to December 2019, divided into three consecutive periods: 1993-2005, 2006-2014, and 2015-2019, which match changes in national allocation policies. Primary outcomes were patient and graft survival, and the relative impact of each study period.

RESULTS

SLT accounted for 8.9% of all liver transplants performed in Italy. A total of 1,715 in situ split liver grafts were included in the analysis: 868 left lateral segments (LLSs) and 847 extended right grafts (ERGs). A significant improvement in patient and graft survival (p <0.001) was observed with ERGs over the three periods. Predictors of graft survival were cold ischaemia time (CIT) <6 h (p = 0.009), UNOS status 2b (p <0.001), UNOS status 3 (p = 0.009), and transplant centre volumes: 25-50 cases vs. <25 cases (p = 0.003). Patient survival was significantly higher with LLS grafts in period 2 vs. period 1 (p = 0.008). No significant improvement in graft survival was seen over the three periods, where predictors of graft survival were CIT <6 h (p = 0.007), CIT <6 h vs. ≥10 h (p = 0.019), UNOS status 2b (p = 0.038), and UNOS status 3 (p = 0.009). Retransplantation was a risk factor in split liver graft recipients, with significantly worse graft and patient survival for both types of graft (p <0.001).

CONCLUSIONS

Our analysis showed Italian SLT outcomes to have improved over the last 25 years. These results could help to dispel reservations regarding the use of this procedure.

IMPACT AND IMPLICATIONS

Split liver transplant(ation) (SLT) is still considered a challenging procedure and is by no means widely accepted. This study included all consecutive in situ SLTs performed in Italy from May 1993 to December 2019. With more than 1,700 cases, it is one of the largest series, examining long-term national trends in in situ SLT since its introduction. The data presented indicate that the outcomes of SLT improved during this 25-year period. Improvements are probably due to better recipient selection, refinements in surgical technique, conservative graft-to-recipient matching, and the continuous, yet carefully managed, expansion of donor selection criteria under a strict mandatory split liver allocation policy. These results could help to dispel reservations regarding the use of this procedure.

MELD 3.0 for adolescent liver transplant candidates

BACKGROUND AND AIMS

Adolescents constitute a unique waitlist cohort that is distinct from younger children. Model for End-stage Liver Disease (MELD) 3.0, which was developed in an adult population of liver transplant candidates, is planned to replace MELD-Sodium in the current liver allocation system for both adults and adolescents aged 12-17. We evaluated the predictive performance of MELD-Sodium, MELD 3.0, and Pediatric End-stage Liver Disease for 90-day waitlist mortality risk among adolescent liver transplant registrants.

APPROACH AND RESULTS

New waitlist registrations for primary liver transplants among individuals aged 12-17 and 18-25 for comparison were identified using Organ Procurement and Transplantation Network (OPTN) data from November 17, 2004, to December 31, 2021. The predictive performance of the current and proposed MELD and Pediatric End-stage Liver Disease scores was assessed using Harrell's concordance ( c ) statistic. There were 1238 eligible listings for adolescents aged 12-17 and 1740 young adults aged 18-25. In the adolescent group, 90-day survival was 97.8%, compared with 95.9% in those aged 18-25 (log-rank p = 0.005), with no significant differences when stratified by sex or indication. Among adolescents, increasing MELD 3.0 was associated with an increased hazard of mortality (HR=1.27, 95% CI: 1.18-1.37), and the c -statistic for 90-day waitlist survival using MELD 3.0 was 0.893 compared with 0.871 using MELD-Sodium and 0.852 using Pediatric End-stage Liver Disease.

CONCLUSIONS

The discriminative ability of MELD 3.0 to rank adolescents according to the risk of death within 90 days was robust. Although MELD 3.0 was initially developed and validated in adults, MELD 3.0 may also improve the prediction of waitlist mortality in adolescents and better represent their urgency for liver transplants.

Can non-directed living liver donation help improve access to grafts and correct socioeconomic disparities in pediatric liver transplantation?

BACKGROUND

Each year, children die awaiting LT as the demand for grafts exceeds the available supply. Candidates with public health insurance are significantly less likely to undergo both deceased donor LT and D-LLD LT. ND-LLD is another option to gain access to a graft. The aim of this study was to evaluate if recipient insurance type is associated with likelihood of D-LLD versus ND-LLD LT.

METHODS

The SRTR/OPTN database was reviewed for pediatric LDLT performed between January 1, 2014 (Medicaid expansion era) and December 31, 2019 at centers that performed ≥1 ND-LLD LDLT during the study period. A multivariable logistic regression was performed to assess relationship between type of living donor (directed vs. non-directed) and recipient insurance.

RESULTS

Of 299 pediatric LDLT, 46 (15%) were from ND-LLD performed at 18 transplant centers. Fifty-nine percent of ND-LLD recipients had public insurance in comparison to 40% of D-LLD recipients (p = .02). Public insurance was associated with greater odds of ND-LLD in comparison to D-LLD upon multivariable logistic regression (OR 2.37, 95% CI 1.23-4.58, p = .01).

CONCLUSIONS

ND-LLD allows additional children to receive LTs and may help address some of the socioeconomic disparity in pediatric LDLT, but currently account for only a minority of LDLT and are only performed at a few institutions. Initiatives to improve access to both D-LLD and ND-LLD transplants are needed.

Pediatric Liver Transplantation

Liver transplantation (LT) for children results in excellent short- and long-term patient and graft survival. LT is a lifesaving procedure in children with acute or chronic liver disease, hepatic tumors, and select genetic metabolic diseases in which it can significantly improve quality of life. In this article, the authors discuss the unique aspects of pediatric LT, including the indications, appropriate patient selection and evaluation, allocation of organs, transplant surgery including the use of variant grafts, posttransplant care including immunosuppression management, prognosis, and transition of care.

Donation after Circulatory Death Liver Transplantation in Paediatric Recipients

Waiting list mortality together, with limited availability of organs, are one of the major challenges in liver transplantation (LT). Especially in the paediatric population, another limiting factor is the scarcity of transplantable liver grafts due to additional concerns regarding graft size matching. In adults, donation after circulatory death (DCD) liver grafts have been used to expand the donor pool with satisfactory results. Although several studies suggest that DCD livers could also be used in paediatric recipients with good outcomes, their utilisation in children is still limited to a small number of reports. Novel organ perfusion strategies could be used to improve organ quality and help to increase the number of DCD grafts utilised for children. With the current manuscript, we present the available literature of LT using DCD grafts in paediatric recipients, discussing current challenges with the use of these livers in children and how machine perfusion technologies could be of impact in the future.

The Landscape of Nondirected Living Liver Donation in the United States

BACKGROUND

Living donor liver transplants (LDLTs) including those from nondirected donors (NDDs) have increased during the past decade, and center-level variations in LDLTs have not yet been described. We sought to quantify changes in the volume of NDD transplants over time and variation in NDD volume between transplant centers. We further examined characteristics of living liver donors and identified factors potentially associated with receiving an NDD liver transplant.

METHODS

Using Scientific Registry of Transplant Recipients data between March 01, 2002, and December 31, 2020, we compared 173 NDDs with 5704 DLDs and 167 NDD recipients with 1153 waitlist candidates.

RESULTS

NDDs increased from 1 (0.4% of LDLTs) in 2002 to 58 (12% of LDLTs) in 2020. Of 150 transplant centers, 35 performed at least 1 NDD transplant. Compared with waitlist candidates, adult NDD recipients were less frequently males (39% versus 62%, P < 0.001), had a lower model for end-stage liver disease (16 versus 18, P = 0.01), and spent fewer days on the waitlist (173 versus 246, P = 0.02). Compared with waitlist candidates, pediatric NDD recipients were younger (50% versus 12% age <2 y, P < 0.001) and more often diagnosed with biliary atresia (66% versus 41%, P < 0.001). Compared with DLDs, NDDs were older (40 versus 35 y, P < 0.001), college educated (83% versus 64%, P < 0.001), White (92% versus 78%, P < 0.001), and more frequently donated left-lateral segment grafts (32.0% versus 14%, P < 0.001).

CONCLUSIONS

Liver NDD transplants continue to expand but remain concentrated at a few centers. Graft distribution favors female adults and pediatric patients with biliary atresia. Racial inequities in adult or pediatric center-level NDD graft distribution were not observed.

Understanding disparities and barriers associated with pediatric transplant evaluation and time to listing: Moving toward a more comprehensive picture

BACKGROUND

Delayed time to listing (TTL) for pediatric transplant patients is associated with increased risks of mortality and morbidity. The full range of health disparities, sociodemographic factors, and other barriers associated with delays in listing in the pediatric transplant candidate evaluation process has not been fully examined.

METHODS

Retrospective chart reviews were conducted for 183 kidney, liver, and heart transplant candidates ages 0-18 who were referred for evaluation during 2012-2015. Demographic information and potential barriers (e g., social/medical factors, financial concerns) were gathered from pre-transplant evaluations and included in a comprehensive model to evaluate mechanisms that explain differences in TTL. Descriptive statistics, logistic regression models, Cox proportional hazards models, and path analysis were used for analyses.

RESULTS

Candidates included 26.8% heart, 33.3% liver, and 39.9% kidney patients. The most common barrier to listing was financial (71.6%), followed by caregiver psychological or substance use (57.9%), and medical problems (49.7%). Higher age, kidney, and liver organ type (relative to the heart), and presence of social, medical, administrative/motivation, and financial barriers were all directly associated with longer TTL. Public insurance was indirectly associated with TTL through social, administrative/motivation, and financial barriers. Organ type was indirectly associated with TTL through financial barriers.

CONCLUSIONS

Results suggest social problems, administrative issues, and financial issues act as mechanisms through which insurance type and liver transplant candidates face increased risk of delays in transplant listing time. There are numerous clinical implications and interventions that are warranted to reduce TTL among pediatric transplant candidates with co-occurring barriers.

Challenging the Traditional Paradigm of Supply and Demand in Pediatric Liver Transplantation Through Nondirected Living Donation: A Case Series

A gap exists between the demand for pediatric liver transplantation and the supply of appropriate size-matched donors. We describe our center's experience with pediatric liver transplantation using anonymous nondirected living liver donors (ND-LLD). First-time pediatric liver transplant candidates listed at our center between January 2012 and June 2020 were retrospectively reviewed and categorized by donor graft type, and recipients of ND-LLD grafts were described. A total of 13 ND-LLD pediatric liver transplantations were performed, including 8 left lateral segments, 4 left lobes, and 1 right lobe. Of the ND-LLD recipients, 5 had no directed living donor evaluated, whereas the remaining 8 (62%) had all potential directed donors ruled out during the evaluation process. Recipient and graft survival were 100% during a median follow-up time of 445 (range, 70-986) days. Of ND-LLDs, 69% were previous living kidney donors, and 1 ND-LLD went on to donate a kidney after liver donation. Of the ND-LLDs, 46% were approved prior to the recipient being listed. Over time, the proportion of living donor transplants performed, specifically from ND-LLDs, increased, and the number of children on the waiting list decreased. The introduction of ND-LLDs to a pediatric liver transplant program can expand the benefit of living donor liver transplantation to children without a suitable directed living donor while achieving excellent outcomes for both the recipients and donors.

Age disparities in transplantation

PURPOSE OF REVIEW

The aim of this review is to outline disparities in liver and kidney transplantation across age spectrum. Disparities do not involve only recipients whose age may severely affect the possibility to access to a potentially life-saving procedure, but donors as well. The attitude of transplant centers to use older donors reflects on waiting list mortality and drop-out. This review examines which age categories are currently harmed and how different allocation systems may minimize disparities.

RECENT FINDINGS

Specific age categories suffer disparities in the access to transplantation. A better understanding of how properly evaluate graft quality, a continuous re-evaluation of the most favorable donor-to-recipient match and most equitable allocation system are the three key points to promote 'justice and equality' among transplant recipients.

SUMMARY

The duty to protect younger patients waiting for transplantation and the request of older patients to have access to potentially life-saving treatment urge the transplant community to use older organs thus increasing the number of available grafts, to evaluate new allocation systems with the aim to maximize 'utility' while respecting 'equity' and to avoid 'futility' thus minimizing waiting list mortality and drop-out, and improving the survival benefits for all patients requiring a transplant.

VIDEO ABSTRACT

http://links.lww.com/COOT/A9.

Living Donor Versus Deceased Donor Pediatric Liver Transplantation: A Systematic Review and Meta-analysis

Reduced-size deceased donors and living donor liver transplantation (LDLT) can address the organ shortage for pediatric liver transplant candidates, but concerns regarding technical challenges and the risk of complications using these grafts have been raised. The aim of this study was to compare outcomes for pediatric LDLT and deceased donor liver transplantation (DDLT) via systematic review.

METHODS

A systematic literature search was performed to identify studies reporting outcomes of pediatric (<18 y) LDLT and DDLT published between 2005 and 2019. A meta-analysis was conducted to examine peri- and postoperative outcomes using fixed- and random-effects models.

RESULTS

Overall, 2518 abstracts were screened, and 10 studies met criteria for inclusion. In total, 1622 LDLT and 6326 DDLT pediatric patients from 4 continents were examined. LDLT resulted in superior patient survival when compared with DDLT at 1, 3, and 5 y post-LT (1-y hazard ratio: 0.58, 95% confidence interval [CI] 0.47-0.73, P < 0.0001). Similarly, LDLT resulted in superior graft survival at all time points post-LT when compared with DDLT (1-y hazard ratio: 0.56 [95% CI 0.46-0.68], P < 0.0001]. The OR for vascular complications was 0.73 (95% CI 0.39-1.39) and 1.31 (95% CI 0.92-1.86) for biliary complications in LDLT compared with DDLT, whereas LDLT was associated with lower rates of rejection (OR: 0.66 [95% CI 0.45-0.96], P = 0.03).

CONCLUSIONS

This meta-analysis demonstrates that LDLT may offer many advantages when compared with DDLT in children and suggests that LDLT should continue to be expanded to optimize outcomes for pediatric LT candidates.

The Surge in Deceased Liver Donors Due to the Opioid Epidemic: Is It Time to Split the Difference?

BACKGROUND

This study aimed to compare trends in use of drug overdose (DO) donors in adult versus pediatric liver transplants and the utilization of split liver transplantation in this donor population.

METHODS

The United Network for Organ Sharing database was reviewed for deceased donor liver transplants from March 2002 to December 2017. Recipients were categorized by donor mechanism of death. Donor splitting criteria was defined as age <40 y, single vasopressor or less, transaminases no >3 times the normal limit, and body mass index ≤ 28 kg/m2.

RESULTS

Adult liver transplants from DO donors increased from 2% in 2002 to 15% in 2017, while pediatric liver transplants from DO donors only increased from <1% to 3% in the same time. While 28% of DO donors met splitting criteria, only 3% of those meeting splitting criteria were used as a split graft. Both pediatric and adult recipients of DO donor livers achieved excellent patient and graft survival.

CONCLUSIONS

DO donors are underutilized in pediatric liver transplantation. Increased splitting of DO donor livers could significantly decrease, if not eliminate, the pediatric liver waiting list.

Cost-Effectiveness of Primary Liver Transplantation Versus Hepatoportoenterostomy in the Management of Biliary Atresia in the United States

Biliary atresia (BA) is the leading indication to perform a pediatric liver transplantation (LT). Timely hepatoportoenterostomy (HPE) attempts to interrupt the natural history and allow for enteric bile flow; however, most patients who are treated with HPE require LT by the age of 10 years. We determined the cost-effectiveness of foregoing HPE to perform primary LT (pLT) in children with BA compared with standard-of-care HPE management. A Markov model was developed to simulate BA treatment over 10 years. Costs were measured in 2018 US dollars and effectiveness in life-years (LYs). The primary outcome was incremental cost-effectiveness ratio (ICER) between treatments. Model parameters were derived from the literature. In the base model, we assumed similar LT outcomes after HPE and pLT. Sensitivity analyses on all model parameters were performed, including a scenario in which pLT led to 100% patient and graft survival after LT. Children undergoing HPE accumulated $316,692 in costs and 8.17 LYs per patient. Children undergoing pLT accumulated $458,059 in costs and 8.24 LYs per patient, costing $1,869,164 per LY gained compared with HPE. With parameter variation over plausible ranges, only post-HPE and post-LT costs reduced the ICER below a typical threshold of $100,000 per LY gained. On probabilistic sensitivity analysis, 93% of iterations favored HPE at that threshold. With 100% patient and graft survival after pLT, pLT cost $283,478 per LY gained. HPE is more economically favorable than pLT for BA. pLT is unfavorable even with no graft or patient loss. The ability to predict those patients who may experience high costs after HPE or low costs after LT may help identify those patients for whom pLT could be considered.

Medium-term outcomes after laparoscopic revision of laparoscopic Kasai portoenterostomy in patients with biliary atresia

OBJECTIVE

To determine whether revision laparoscopic Kasai portoenterostomy (RLKPE) is a viable treatment option for patients with biliary atresia (BA) who had undergone initially successful laparoscopic Kasai portoenterostomy (ILKPE).

METHODS

The medical records of 312 patients with nonsyndromic BA who had undergone ILKPE between May 2009 and May 2017 were retrospectively reviewed. The patients were divided into three groups according to their outcomes after ILKPE: group A: 25 patients who had undergone RLKPE; group B: 203 patients who had undergone ILKPE and required no further surgical intervention; group C: 84 patients with failed ILKPE who had either died or required liver transplantation for survival. The 3-year and 5-year survival with native liver (SNL) rates were compared between groups A and B and between groups A and C. Among the 25 patients in group A, the perioperative data of RLKPE were compared with those of ILKPE.

RESULTS

Of the 312 patients who had undergone ILKPE, 228 reached the normal bilirubin concentration range within 6 months postoperatively. Among them, 25 patients with a sudden cessation of bile flow had undergone RLKPE. Adequate biliary drainage, as evidenced by normalized conjugated bilirubin levels, was achieved in 80% of patients who had undergone RLKPE. The perioperative variables, including the operative time, blood loss, rate of conversion to open surgery and complications of RLKPE, were not significantly different between RLKPE and ILKPE. The 3-year and 5-year SNL rates in patients after RLKPE were 64.0% and 52.0%, respectively, which were not significantly different from the corresponding rates of 86.2% and 73.9%, respectively, in patients after unrevised ILKPE (P > 0.05).

CONCLUSION

Our data demonstrated that RPLKE is a viable and effective treatment option in patients with sudden cessation of bile drainage after ILKPE. RPLKE can delay the need for liver transplantation, yielding encouraging medium-term patient outcomes.

A Review of the Current State of Liver Transplantation Disparities

Equity in access is one of the core goals of the Organ Procurement and Transplant Network (OPTN). However, disparities in liver transplantation have been described since the passage of the National Organ Transplant Act, which established OPTN in the 1980s. During the past few decades, several efforts have been made by the United Network for Organ Sharing (UNOS) to address disparities in liver transplantation with notable improvements in many areas. Nonetheless, disparities have persisted across insurance type, sex, race/ethnicity, geographic area, and age. African Americans have lower rates of referral to transplant centers, females have lower rates of transplantation from the liver waiting list than males, and public insurance is associated with worse posttransplant outcomes than private insurance. In addition, pediatric candidates and older adults have a disadvantage on the liver transplant waiting list, and there are widespread regional disparities in transplantation. Given the large degree of inequity in liver transplantation, there is a tremendous need for studies to propose and model policy changes that may make the liver transplant system more just and equitable.

Organ utilization - the next hurdle in transplantation?

Nonutilization of organs from consented deceased donors remains a significant factor in limiting patient access to transplantation. Critical to reducing waste is a clear understanding of why organs are not used: accurate metrics are essential to identify the extent and causes of waste but use of these measures as targets or comparators between units/jurisdictions must be done with caution as focus on any one measure may result in unintended adverse consequences. Comparison between centres or countries may be misleading because of variation in definitions, patient or graft characteristics. Two of the most challenging areas to improve appropriate deceased donor organ utilization are appetite for risk and lack of validated tools to help identify an organ that will function appropriately. Currently, the implanting surgeon is widely considered to be accountable for the use of a donated organ so guidelines must be clear to allow and support sensible decisions and recognition that graft failure or inadvertent disease transmission are not necessarily attributable to poor decision-making. Accepting an organ involves balancing risk and benefit for the potential recipient. Novel technologies such as machine perfusion may allow for more robust guidance as to the functioning of the organ.

Livers From Pediatric Donation After Circulatory Death Donors Represent a Viable and Underutilized Source of Allograft

Despite increased numbers of donation after circulatory death (DCD) donors, pediatric DCD livers are underused. To investigate possible reasons for this discrepancy, we conducted a retrospective cohort study using 2 data sets from the Organ Procurement and Transplantation Network for all deceased liver donors and for all recipients of DCD liver transplants from March 8, 1993, to June 30, 2018. Pediatric (0-12 years) and adolescent (13-17 years) DCD donors were compared with those aged 18-40 years. We found that pediatric DCD allografts are recovered at a significantly lower rate than from 18-to-40-year-old donors (27.3% versus 56.3%; P < 0.001). However, once recovered, these organs are transplanted at a similar rate to those from the 18-to-40-year-old donor cohort (74.7% versus 74.2%). Significantly more pediatric DCD livers (odds ratio [OR], 3.75; confidence interval [CI], 3.14-4.47) were not recovered compared with adult organs, which were most commonly not recovered due to organ quality (10.2% versus 7.1%; P < 0.001). The 10-year relative risks (RRs) for graft failure and patient death were similar between pediatric and adult DCD donors, with adolescent DCD livers demonstrating improved outcomes. DCD livers transplanted into pediatric donors were protective against graft failure (RR, 0.46; 95% confidence interval [CI], 0.21-0.99) and patient death (RR, 0.16; 95% CI, 0.04-0.69). In conclusion, despite lower rates of recovery, pediatric DCD livers represent a viable organ source for certain adults and children.

Impact of Acuity Circles on Outcomes for Pediatric Liver Transplant Candidates

BACKGROUND

In December 2018, United Network for Organ Sharing approved an allocation scheme based on recipients' geographic distance from a deceased donor (acuity circles [ACs]). Previous analyses suggested that ACs would reduce waitlist mortality overall, but their impact on pediatric subgroups was not considered.

METHODS

We applied Scientific Registry of Transplant Recipients data from 2011 to 2016 toward the Liver Simulated Allocation Model to compare outcomes by age and illness severity for the United Network for Organ Sharing-approved AC and the existing donor service area-/region-based allocation schemes. Means from each allocation scheme were compared using matched-pairs t tests.

RESULTS

During a 3-year period, AC allocation is projected to decrease waitlist deaths in infants (39 versus 55; P < 0.001), children (32 versus 50; P < 0.001), and teenagers (15 versus 25; P < 0.001). AC allocation would increase the number of transplants in infants (707 versus 560; P < 0.001), children (677 versus 547; P < 0.001), and teenagers (404 versus 248; P < 0.001). AC allocation led to decreased median pediatric end-stage liver disease/model for end-stage liver disease at transplant for infants (29 versus 30; P = 0.01), children (26 versus 29; P < 0.001), and teenagers (26 versus 31; P < 0.001). Additionally, AC allocation would lead to fewer transplants in status 1B in children (97 versus 103; P = 0.006) but not infants or teenagers. With AC allocation, 77% of pediatric donor organs would be allocated to pediatric candidates, compared to only 46% in donor service area-/region-based allocation (P < 0.001).

CONCLUSIONS

AC allocation will likely address disparities for pediatric liver transplant candidates and recipients by increasing transplants and decreasing waitlist mortality. It is more consistent with federally mandated requirements for organ allocation.

Deceased Donor Predictors for Pediatric Liver Allograft Utilization

BACKGROUND

The number of pediatric deceased organ donors has recently declined, and the nonutilization of pediatric liver allografts has limited the development of liver transplantation. We determined the utilization rate of pediatric livers and identified risk factors for graft discard.

METHODS

We used data from the Scientific Registry of Transplant Recipients database from January 1, 2000, to December 31, 2012. The trends of pediatric liver donors and utilization rates were analyzed. Donor risk factors that impacted the graft use of pediatric livers were measured. Logistic regression modelling was performed to evaluate graft utilization and risk factors.

RESULTS

A total of 11,934 eligible pediatric liver donors were identified during this period. A total of 1191 authorized liver grafts did not recover or recovered without transplantation. Factors including pediatric donors >1 year of age (odds ratio [OR] = 2.956, 95% confidence interval [CI] 2.494-3.503, P < .001), nonhead trauma (OR = 2.243, 95% CI 1.903-2.642, P < .001), lack of heartbeat (OR = 7.534, 95% CI 5.899-9.623, P < .001), hepatitis B surface antigen positivity (OR = 4.588, 95% CI 1.021-20.625, P = .047), anti-hepatitis C virus positivity (OR = 4.691, 95% CI 1.352-16.280, P = .015), total bilirubin >1 mg/dL (OR = 1.743, 95% CI 1.469-2.068, P < .001), and blood urea nitrogen >21 mg/dL (OR = 1.941, 95% CI 1.546-2.436, P < .001) were significantly related to graft nonutilization. Steroids or diuretics administered prerecovery were significantly related to graft utilization (OR = 0.684, 95% CI 0.581-0.806, P < .001; OR = 0.744, 95% CI 0.634-0.874, P < .001; respectively).

CONCLUSIONS

The pediatric liver allograft utilization rate and risk factors for nonutilization of grafts were determined.

The impact of public health service increased risk donors in pediatric liver transplantation

Many transplant programs are reluctant to use organs from deceased donors designated as "PHS increased risk" due to misconceptions regarding the quality of those organs. This study evaluated the impact of PHS increased risk donors on patient and allograft survival in pediatric patients undergoing liver transplantation. Retrospective analysis of the UNOS database from January 2005 through September 2017 revealed 5615 pediatric patients who underwent isolated liver transplantation; of these, 5057 patients received primary isolated liver transplants and 558 patients received isolated liver retransplants. PHS increased risk organs were used in 6.7% and 5.4% of the children receiving primary isolated and retransplant livers, respectively. Cox proportional hazards models adjusted for donor and recipient characteristics determined the relative risk of PHS status on allograft and patient survival. Sicker children (those in ICU [P < .001] and on life support [P = .04]) were more likely to receive PHS increased risk donor organs. There were no differences in overall patient (P = .61) or allograft (P = .68) survival between pediatric patients receiving PHS positive vs PHS negative deceased donor organs; adjusted models also demonstrated no statistically significant differences in patient or allograft survival. Excellent patient and allograft survival can be accomplished with PHS increased risk organs.

Hepatic expression of HGF/C-met and native liver survival in biliary atresia

BACKGROUND

The prognosis of biliary atresia (BA) remains difficult to predict. This study evaluated the roles of hepatocyte growth factor (HGF) and its receptor (C-met) towards clinical outcome and native liver survival.

METHODS

Hepatic HGF and C-met expression were determined using immunohistochemistry from liver biopsies of 41 BA patients during Kasai operation, and 17 non-cholestatic patients. The HGF and C-met expression was visually scored as per its intensity and percentage of stained area. BA patients were classified as high- and low-HGF and C-met receptor status. Native liver survival was compared between the two groups at 3-year follow-up. Data are shown as median and range.

MAIN RESULTS

Median age of BA patients was 2 (1-6) months. Hepatic HGF and C-met staining scores of BA patients were higher than those of non-cholestatic patients (P < 0.0001). There was a correlation between HGF and C-met staining scores (spearman r = 0.77, P < 0.0001). However, there was no association between their expression and early outcome at 6 months post-op. Mean follow-up time was 68.6 months. Survival analysis revealed that native liver survival at 1 year and 3 years were 88% and 77%, respectively. Additionally, 82.6% (19/23) of patients in the low-HGF group survived with native liver, compared with 66.7% (10/15) of those in high-HGF group (P = 0.436). For C-met expression, 78.6% (22/28) of low-score and 70% (7/10) of high score groups survived with native liver (P = 0.673).

CONCLUSIONS

Strong expression of hepatic HGF and its receptor in BA patients was demonstrated. However, the expression was not associated with the early outcome and native liver survival. These results suggest that HGF involved in the liver pathology of BA but its expression cannot be used as a prognostic indicator. Small sample size of patients was a main limitation. Further studies are warranted to validate our findings.

Split liver transplantation is utilized infrequently and concentrated at few transplant centers in the United States

Split liver transplantation (SLT) is 1 strategy for maximizing the number of deceased donor liver transplants. Recent reports suggest that utilization of SLT in the United States remains low. We examined deceased donor offers that were ultimately split between 2010 and 2014. SLTs were categorized as "primary" and "secondary" transplants. We analyzed allocation patterns and used logistic regression to evaluate factors associated with secondary split discard. Four hundred eighteen livers were split: 54% from adult, 46% from pediatric donors. Of the 227 adult donor livers split, 61% met United Network for Organ Sharing "optimal" split criteria. A total of 770 recipients (418 primary and 352 secondary) were transplanted, indicating 16% discard. Ninety-two percent of the 418 primary recipients were children, and 47% were accepted on the first offer. Eighty-seven percent of the 352 secondary recipients were adults, and 7% were accepted on the first offer. Of the 352 pairs, 99% were transplanted in the same region, 36% at the same center. In logistic regression, shorter donor height was associated with secondary discard (odds ratio 0.97 per cm, 95% CI 0.94-1.00, P = .02). SLT volume by center was not predictive of secondary discard. Current policy proposals that incentivize SLT in the United States could increase the number of transplants to children and adults.

Short- and Long-Term Outcomes After Live-Donor Transplantation with Hyper-Reduced Liver Grafts in Low-Weight Pediatric Recipients

OBJECTIVE

To evaluate short- and long-term outcomes after live-donor liver transplantation (LT) with hyper-reduced grafts in low-weight pediatric recipients. LT is an established curative therapy for children with end-stage chronic liver disease or acute liver failure. A major problem in pediatric LT has been the lack of size-matched donor organs. The disadvantage of the use of large-for-size grafts is the insufficient tissue oxygenation and graft compression, which result in poor outcomes. The shortage of suitable donors is most notable in children under 10 kg. To overcome such obstacle, in situ hyper-reduced live-donor liver grafts have been introduced. Available articles in the literature are based on small samples and are deficient in long-term follow-up.

METHODS

A single-cohort, retrospective analysis was conducted including 59 pediatric patients under 10 kg who underwent hyper-reduced (in situ "a la carte" left lateral segment reduction) live-donor LT (LDLT) between February 1994 and February 2018.

RESULTS

The most frequent cause of liver failure was biliary atresia (70%). Median recipient weight was 8 kg. Vascular complications were confirmed in 15% of the sample, while 45% presented biliary complications. Median follow-up time was 40.3 months. Ten-year overall survival rate was 74%. Pediatric end-stage liver disease score > 23 was associated with a higher risk of post-operative complications.

CONCLUSION

LDLT can be undertaken in children with body weight < 10 kg achieving good results in high-volume centers by experienced surgeons.

Feasibility and safety of using low-body-weight donors in pediatric liver transplantation

BACKGROUND

Donors with low-body-weight were previously reported to be related to inferior recipient outcomes in pediatric liver transplantation. However, the scarce availability of age and size-matched organs has encouraged us to re-evaluate the feasibility and safety of using low-body-weight donors.

METHODS

We retrospectively analyzed 91 deceased donor pediatric liver transplantation between January 2014 and December 2016, donor weight less than 5 kg was defined as low-body-weight donors. The recipients were divided into two groups according to donor weight. (≤5 kg and 5 kg < to ≤20 kg). Donor and recipient characteristics, perioperative data, postoperative complications as well as graft and recipient survival rate were compared RESULTS: The recipients and grafts recovery after transplantation were comparable between two groups. The recipients receiving low-body-weight donors showed higher risk of hepatic artery thrombosis and small-for-size syndrome, however, these complications can effectively be treated by our strategies. The 2-year patient survival rates were 92.9% and 95.2%, 2-year graft survival rates were 92.9% and 93.7% in Groups 1 and 2, without significant difference.

CONCLUSIONS

Our finding suggested that the utility of livers from low-body-weight donors is a potential strategy to increase donor availability in well-selected pediatric recipients.

LEVEL OF EVIDENCE

III.

Frequency of whole-organ in lieu of split-liver transplantation over the last decade: Children experienced increased wait time and death

Organ shortage is a barrier to liver transplantation (LT). Split LT (SLT) increases organ utilization, saving 2 recipients. A simulation of Organ Procurement and Transplantation Network/United Network for Organ Sharing data (2007-2017) was performed to identify whole-organ LT grafts (WLT) that met the criteria for being splittable to 2 recipients. Waitlist consequences presented. Deceased donor (DD) livers transplanted as whole organs were evaluated for suitability to split. Of these DD organs, we identified the adolescent and adult recipients of WLT who were suitable for SLT. Pediatric candidates suitable to share the SLT were ascertained from DD match-run lists, and 1342 splittable DD organs were identified; 438 WLT recipients met the criteria for accepting a SLT. Review of the 438 DD match-run lists identified 420 children next on the list suitable for SLT. Three hundred thirty-three children (79%) underwent LT, but had longer wait-times compared to 591 actual pediatric SLT recipients (median 147 days vs 44 days, P  < 0.001). Thirty-three of 420 children died on waitlist after a mean 206 days (standard deviation 317). Sharing organs suitable for splitting increases the number of LT, saving more lives. With careful patient selection, SLT will not be a disadvantage to the adult recipients. With a children-first allocation scheme, SLT will naturally increase the number of allografts because adult organs are too large for small children.

Lipid nanoparticle-targeted mRNA therapy as a treatment for the inherited metabolic liver disorder arginase deficiency

Arginase deficiency is caused by biallelic mutations in arginase 1 (ARG1), the final step of the urea cycle, and results biochemically in hyperargininemia and the presence of guanidino compounds, while it is clinically notable for developmental delays, spastic diplegia, psychomotor function loss, and (uncommonly) death. There is currently no completely effective medical treatment available. While preclinical strategies have been demonstrated, disadvantages with viral-based episomal-expressing gene therapy vectors include the risk of insertional mutagenesis and limited efficacy due to hepatocellular division. Recent advances in messenger RNA (mRNA) codon optimization, synthesis, and encapsulation within biodegradable liver-targeted lipid nanoparticles (LNPs) have potentially enabled a new generation of safer, albeit temporary, treatments to restore liver metabolic function in patients with urea cycle disorders, including ARG1 deficiency. In this study, we applied such technologies to successfully treat an ARG1-deficient murine model. Mice were administered LNPs encapsulating human codon-optimized ARG1 mRNA every 3 d. Mice demonstrated 100% survival with no signs of hyperammonemia or weight loss to beyond 11 wk, compared with controls that perished by day 22. Plasma ammonia, arginine, and glutamine demonstrated good control without elevation of guanidinoacetic acid, a guanidino compound. Evidence of urea cycle activity restoration was demonstrated by the ability to fully metabolize an ammonium challenge and by achieving near-normal ureagenesis; liver arginase activity achieved 54% of wild type. Biochemical and microscopic data showed no evidence of hepatotoxicity. These results suggest that delivery of ARG1 mRNA by liver-targeted nanoparticles may be a viable gene-based therapeutic for the treatment of arginase deficiency.

A learning health network for pediatric liver transplantation: Inaugural meeting report from the Starzl Network for Excellence in Pediatric Transplantation

Learning Health Networks (LHN) improve the well-being of populations by aligning clinical care specialists, technology experts, patients and patient advocates, and other thought leaders for continuous improvement and seamless care delivery. A novel LHN focused on pediatric transplantation, the Starzl Network for Excellence in Pediatric Transplantation (SNEPT), convened its inaugural meeting in September 2018. Clinical care team representatives, patients, and patient families/advocates partnered to take part in educational sessions, pain point exercises, and project identification workshops. Participants discussed the global impact of transplant from both a population and individual perspective, identifying challenges and opportunities where the Starzl Network could work to improve outcomes at scale across a variety of transplant-related conditions.

Split Liver Transplantation and Pediatric Waitlist Mortality in the United States: Potential for Improvement

BACKGROUND

In the United States, 1 in 10 infants and 1 in 20 older children die on the liver transplant waiting list. Increasing split liver transplantation could increase organ availability for these children, without decreasing transplants in adults.

METHODS

Using United Network for Organ Sharing Standard Transplant Analysis and Research data, we identified livers transplanted 2010 to 2015 that could potentially have been used for split transplant, based on strict criteria. Livers not suitable for pediatric patients or allocated to high-risk recipients were excluded. Number and distribution of potentially "split-able" livers were compared to pediatric waitlist deaths in each region.

RESULTS

Of 37 333 deceased donor livers transplanted, 6.3% met our strict criteria for utilization in split liver transplant. Only 3.8% of these were actually utilized for split liver transplantation. 96% were used for a single adult recipient. Of the 2253 transplanted as whole livers, 82% of their recipients were listed as willing to accept a segmental liver, and only 3% were listed as requiring a cold ischemia time less than 6 hours. Over the same 5 years, 299 children died on the waitlist. In every United Network for Organ Sharing region, there were more potentially "split-able" livers than pediatric waitlist deaths. Thirty-seven percent of pediatric waitlist deaths occurred at transplant centers that averaged 1 or less pediatric split liver transplantation annually during the study period.

CONCLUSIONS

This comparison, although not conclusive, suggests that we might be missing opportunities to reduce pediatric waitlist mortality without decreasing access for adults-using split liver transplant. Barriers are significant, but further work on strategies to increase split liver transplant is warranted.

A national mandatory-split liver policy: A report from the Italian experience

To implement split liver transplantation (SLT) a mandatory-split policy has been adopted in Italy since August 2015: donors aged 18-50 years at standard risk are offered for SLT, resulting in a left-lateral segment (LLS) graft for children and an extended-right graft (ERG) for adults. We aim to analyze the impact of the new mandatory-split policy on liver transplantation (LT)-waiting list and SLT outcomes, compared to old allocation policy. Between August 2015 and December 2016 out of 413 potentially "splittable" donors, 252 (61%) were proposed for SLT, of whom 53 (21%) donors were accepted for SLT whereas 101 (40.1%) were excluded because of donor characteristics and 98 (38.9%) for absence of suitable pediatric recipients. The SLT rate augmented from 6% to 8.4%. Children undergoing SLT increased from 49.3% to 65.8% (P = .009) and the pediatric LT-waiting list time dropped (229 [10-2121] vs 80 [12-2503] days [P = .045]). The pediatric (4.5% vs 2.5% [P = .398]) and adult (9.7% to 5.2% [P < .001]) LT-waiting list mortality reduced; SLT outcomes remained stable. Retransplantation (HR = 2.641, P = .035) and recipient weight >20 kg (HR = 5.113, P = .048) in LLS, and ischemic time >8 hours (HR = 2.475, P = .048) in ERG were identified as predictors of graft failure. A national mandatory-split policy maximizes the SLT donor resources, whose selection criteria can be safely expanded, providing favorable impact on the pediatric LT-waiting list and priority for adult sick LT candidates.

Social, economic, and policy implications of organ preservation advances

PURPOSE OF REVIEW

Despite over 60 years of progress in the field of since the first organ transplant, insufficient organ preservation capabilities still place profound constraints on transplantation. These constraints play multiple and compounding roles in the predominant limitations of the field: the severe shortages of transplant organs, short-term and long-term posttransplant outcomes and complications, the unmet global need for development of transplant infrastructures, and economic burdens that limit patient access to transplantation and contribute to increasing global healthcare costs. This review surveys ways that advancing preservation technologies can play a role in each of these areas, ultimately benefiting thousands if not millions of patients worldwide.

RECENT FINDINGS

Preservation advances can create a wide range of benefits across many facets of organ transplantation, as well as related areas of transplant research. As these technologies mature, so will the policies around their use to maximize the benefits offered by organ preservation.

SUMMARY

Organ preservation advances stand to increase local and global access to transplantation, improve transplant outcomes, and accelerate progress in related areas such as immune tolerance induction and xenotransplantation. This area holds the potential to save the healthcare system many billions of dollars and reduce costs across many aspects of transplantation. Novel preservation technologies, along with other technologies facilitated by preservation advances, could potentially save millions of lives in the coming years.

The Impact of Increased Allocation Priority for Children Awaiting Liver Transplant: A Liver Simulated Allocation Model (LSAM) Analysis

OBJECTIVE

The aim of the study was to investigate the impact of prioritizing infants, children, adolescents, and the sickest adults (Status 1) for deceased donor livers. We compared outcomes under two "SharePeds" allocation schema, which prioritize children and Status 1 adults for national sharing and enhanced access to pediatric donors or all donors younger than 35 years, to outcomes under the allocation plan approved by the Organ Procurement and Transplant Network in December 2017 (Organ Procurement and Transplantation Network [OPTN] 12-2017).

METHODS

The 2017 Liver Simulated Allocation Model and Scientific Registry of Transplant Recipients data on all US liver transplant candidates and liver offers 7/2013 to 6/2016 were used to predict waitlist deaths, transplants, and post-transplant deaths under the OPTN 12-2017 and SharePeds schema.

RESULTS

Prioritizing national sharing of pediatric donor livers with children (SharePeds 1) would decrease waitlist deaths for infants (<2 years, P = 0.0003) and children (2-11 years, P = 0.001), with no significant change for adults (P = 0.13). Prioritizing national sharing of all younger than 35-year-old deceased donor livers with children and Status 1A adults (SharePeds 2) would decrease waitlist deaths for infants, children, and all Status 1A/B patients (P < 0.0001 for each). SharePeds 1 and 2 would increase the number of liver transplants done in infants, children, and adolescents compared to the OPTN-2017 schema (P < 0.00005 for all age groups). Both SharePeds schema would increase the percentage of pediatric livers transplanted into pediatric recipients.

CONCLUSIONS

Waitlist deaths could be significantly decreased, and liver transplants increased, for children and the sickest adults, by prioritizing children for pediatric livers and with broader national sharing of deceased donor livers.

Deceased Pediatric Donor Livers: How Current Policy Drives Allocation and Transplantation

Each year, approximately 60 children, representing 12% of waitlist candidates, die awaiting liver transplantation. The current allocation algorithm for pediatric donor livers prioritizes local/regional adults over national children. We attempted to better understand the impact of the present algorithm on pediatric candidates. We analyzed pediatric donor liver offers from 2010 to 2014. Donors and recipients were classified based on age. We mapped allocation and acceptance patterns and used subgroup analyses to explore the significance of donor service areas (DSAs) with low pediatric transplant volumes. We used Cox proportional hazard regressions to evaluate posttransplantation outcomes: 3,318 pediatric donor livers were transplanted into 3,482 recipients, and 45% (1,569) were adults. Of the 1,569 adults, 25% (390) received a pediatric organ that was never offered to children; 52% (204) of these 390 pediatric organs originated in the 37 DSAs, with ≤25 pediatric liver transplantations; 278 children died or were delisted due to illness during the same time, with higher mortality rates in the 37 DSAs (10% versus 6%, P < 0.01). Compared to adults, pediatric recipients aged <12 years had lower risks of posttransplant mortality (hazard ratio, 0.62; 95% confidence interval, 0.46-0.81; P < 0.01). Conclusions: We found that 45% of pediatric donor livers were transplanted into adults: 390 adults were transplanted with pediatric organs never offered to children, while 278 children died or were delisted due to illness, which was more apparent in DSAs with low pediatric transplant volumes; we advocate for a change to allocation policies to allow pediatric organs to be offered to national children with status 1B or Model for End-Stage Liver Disease/Pediatric End-Stage Liver Disease >15 before being offered to local/regional + circle non-status 1A adults.

Superior Outcomes and Reduced Wait Times in Pediatric Recipients of Living Donor Liver Transplantation

Background

Living donor liver transplantation (LDLT) is increasingly used to bridge the gap between the current supply and demand imbalance for deceased donor organs to provide lifesaving liver transplantation.

Methods

Outcomes of 135 children who underwent LDLT were compared with 158 recipients of deceased donor liver transplantation (DDLT) at the largest pediatric liver transplant program in Canada.

Results

Recipients of LDLT were significantly younger than deceased donor recipients (P ≤ 0.001), less likely to require dialysis pretransplant (P < 0.002) and had shorter wait time duration when the primary indication was cholestatic liver disease (P = 0.003). The LDLT donors were either related genetically or emotionally (79%), or unrelated (21%) to the pediatric recipients. One-, 5-, and 10-year patient survival rates were significantly higher in LDLT (97%, 94%, and 94%) compared with DDLT (92%, 87%, and 80%; log-rank P = 0.02) recipients, as were graft survival rates (96%, 93%, and 93% for LDLT versus 89%, 81.4%, and 70%, respectively, for DDLT; log-rank P = 0.001). Medical and surgical complications were not statistically different between groups. Graft failure was higher in recipients of DDLT (odds ratio, 2.60; 95% confidence interval, 1.02, 6.58) than in the LDLT group after adjustment for clinical characteristics and propensity score.

Conclusions

Living donor liver transplantation provides superior outcomes for children and is an excellent and effective strategy to increase the chances of receiving a liver transplant.

Expansion of the Liver Donor Supply Through Greater Use of Split-Liver Transplantation: Identifying Optimal Recipients

The increased use of split-liver transplantation (SLT) represents a strategy to increase the supply of organs. Although outcomes after SLT and whole liver transplantation (WLT) are similar on average among pediatric recipients, we hypothesized that the relationship between graft type and outcomes may vary depending on patient, donor, and surgical characteristics. We evaluated graft survival among pediatric (<18 years) deceased donor, liver-only transplant recipients from March 2002 until December 2015 using data from the Scientific Registry of Transplant Recipients. Graft survival was assessed in a Cox proportional hazards model, with and without effect modification between graft type and donor, recipient, and surgical characteristics, to identify conditions where the risk of graft loss for SLT and WLT were similar. In a traditional multivariable model, characteristics associated with graft loss included donor age >50 years, recipient weight <10 kg, acute hepatic necrosis, autoimmune diseases, tumor, public insurance, and cold ischemia time (CIT) >8 hours. In an analysis that explored whether these characteristics modified the relationship between graft type and graft loss, many characteristics associated with loss actually had similar outcomes regardless of graft type, including weight <10 kg, acute hepatic necrosis, autoimmune diseases, and tumor. In contrast, several subgroups had worse outcomes when SLT was used, including recipient weight 10-35 kg, non-biliary atresia cholestasis, and metabolic disease. Allocation score, share type, or CIT did not modify risk of graft type and graft failure. Although one might anticipate that individuals with higher rates of graft loss would be worse candidates for SLT, data suggest that these patients actually have similar rates of graft loss. These findings can guide surgical decision making and may support policy changes that promote the increased use of SLT for specific pediatric recipients.

ABO-incompatible deceased donor pediatric liver transplantation: Novel titer-based management protocol and outcomes

ABO-ILT have re-emerged as an alternate option for select patients awaiting transplant. However, treatment protocols for children undergoing deceased donor ABO-ILT are not standardized. We implemented a novel IS protocol for children undergoing deceased donor ABO-ILT based on pretransplant IH titers. Children with high pretransplant IH titers (≥1:32) underwent an enhanced IS protocol including plasmapheresis, rituximab, IVIG, and mycophenolate, while children with IH titers ≤1:16 received steroids and tacrolimus. We retrospectively assessed our outcomes of ABO-ILT with ABO-compatible recipients of similar age and diagnosis over a 2-year period. Ten children with median age of 8.9 months underwent ABO-ILT, 4 of 10 patients underwent enhanced IS due to high IH titers. Rates of complications (rejection, infections, biliary, and vascular) at both 1 year and up to 3 years post-transplant were comparable between the groups. Patients with ABO-ILT had good graft function with 100% survival at a median follow-up of 3.3 years. In conclusion, IS tailored to pretransplant IH titers in pediatric deceased donor ABO-ILT is feasible and can achieve outcomes similar to ABO-CLT at 1 and 3 years post-transplantation.

Liver Transplantation in Children

Liver transplantation (LT) for children has excellent short- and long-term patient and graft survival. LT is a lifesaving procedure in children with acute or chronic liver disease, hepatic tumors, and a few genetic metabolic diseases in which it can significantly improve quality of life. In this article, the authors discuss the unique aspects of pediatric LT, including the indications, patient selection and evaluation, allocation, transplant surgery and organ selection, posttransplant care, prognosis, adherence, and transition of care.

Receipt of a pediatric liver offer as the first offer reduces waitlist mortality for adult women

In liver transplantation, adults with small stature have a greater susceptibility to waitlist mortality. This may explain the persistent waitlist mortality disparity that exists for women. We hypothesized that women who receive early offers of pediatric donor livers have improved waitlist survival, and that preferentially offering these organs to women mitigates this sex-based disparity. We analyzed donor liver offers from 2010 to 2014. Adult candidates who received a first offer that ranked within the first three match run positions from the donors' perspective were classified based on gender and whether they received a pediatric versus adult offer. We used competing risks regression to associate first offer type and waitlist mortality. A total of 8,101 waitlist candidates received a first offer that was ranked within the first three match run positions: 5.6% (293/5,202) men and 6.2% (179/2,899) women received a pediatric donor liver as their first offer. In multivariable analyses, compared with adult-first men, adult-first women (subhazard ratio [sHR] 1.33, 95% confidence interval 1.17-1.51, P < 0.01) had an increased pretransplant mortality risk while pediatric-first men and pediatric-first women had noninferior risks of morality. Pediatric-to-adult and adult-to-adult recipients had similar risks of graft failure and posttransplant mortality.

CONCLUSION

Our study examines allograft selection by donor age, recipient sex, and in effect size as a means to address disparities in waitlist mortality. We found that women who received a pediatric donor liver as the first offer had a lower risk of waitlist mortality compared with those who receive adult offers. Our data provides a simple approach to mitigating the increased waitlist mortality experienced by women by incorporating donor and recipient size as variables into organ allocation. (Hepatology 2018).

Variability in acceptance of organ offers by pediatric transplant centers and its impact on wait-list mortality

Recent data have suggested that pediatric patients wait-listed for a liver transplantation frequently have liver offers declined. However, factors associated with liver offer decisions and center-level variability in practice patterns have not been explored. We evaluated United Network for Organ Sharing data on all match runs from May 1, 2007 to December 31, 2015 in which the liver was offered to ≥1 pediatric patient; the transplant recipient was ranked in the first 40 positions for the organ offer; and the donor was brain-dead and <50 years of age. We used multilevel mixed effects models to evaluate factors associated with organ offer acceptance, among-center variability, and the association between center-level acceptance and wait-list mortality. There were 4088 unique pediatric patients during the study period, comprising 27,094 match runs. Initial Model for End-Stage Liver Disease or Pediatric End-Stage Liver Disease score, history of exception points, recipient region, rank on match run, and geographic share type were all associated with probability of offer acceptance. There was significant among-center variation (P < 0.001) in adjusted liver offer acceptance rates, accounting for donor, recipient, and match-related factors (adjusted acceptance rates: median, 8.9%; range, 5.1%-14.6%). Center-level acceptance rates were associated with wait-list mortality, with a >10% increase in the risk of wait-list mortality for every 1% decrease in a center's adjusted liver offer acceptance rate (odds ratio, 1.10; 95% confidence interval, 1.01-1.19). In conclusion, there is significant among-center variability in liver offer acceptance rates for pediatric patients that is not explained by donor and recipient factors. A center's liver acceptance behavior significantly impacts whether a pediatric patient will be transplanted or die on the waiting list. Liver Transplantation 24 803-809 2018 AASLD.

Fifteen-Year Trends in Pediatric Liver Transplants: Split, Whole Deceased, and Living Donor Grafts

OBJECTIVE

To evaluate changes in patient and graft survival for pediatric liver transplant recipients since 2002, and to determine if these outcomes vary by graft type (whole liver transplant, split liver transplant [SLT], and living donor liver transplant [LDLT]).

STUDY DESIGN

We evaluated patient and graft survival among pediatric liver-only transplant recipients the PELD/MELD system was implemented using the Scientific Registry of Transplant Recipients.

RESULTS

From 2002-2009 to 2010-2015, survival for SLT at 30 days improved (94% vs 98%; P < .001), and at 1 year improved for SLT (89% to 95%; P <.001) and LDLT (93% to 98%; P = .002). There was no change in survival for whole liver transplant at either 30 days (98% in both; P = .7) or 1 year (94% vs 95%; P = .2). The risk of early death with SLT was 2.14-fold higher in 2002-2009 (adjusted hazard ratio [aHR] vs whole liver transplant, 1.472.143.12), but this risk disappeared in 2010-2015 (aHR, 0.651.131.96), representing a significant improvement (P = .04). Risk of late death after SLT was similar in both time periods (aHR 2002-2009, 0.871.141.48; aHR 2010-2015, 0.560.881.37). LDLT had similar risk of early death (aHR 2002-2009, 0.491.032.14; aHR 2010-2015, 0.260.742.10) and late death (aHR 2002-2009, 0.520.831.32; aHR 2010-2015, 0.170.441.11). Graft loss was similar for SLT (aHR, 0.931.091.28) and was actually lower for LDLT (aHR, 0.530.710.95).

CONCLUSIONS

In recent years, outcomes after the use of technical variant grafts are comparable with whole grafts, and may be superior for LDLT. Greater use of technical variant grafts might provide an opportunity to increase organ supply without compromising post-transplant outcomes.

Donation after Circulatory Death in Paediatric Liver Transplantation: Current Status and Future Perspectives in the Machine Perfusion Era

Efforts have been made by the transplant community to expand the deceased donor pool in paediatric liver transplantation (LT). The growing experience on donation after circulatory death (DCD) for adult LT has encouraged its use also in children, albeit in selective cases, opening new perspectives for paediatric patients. Even though there has recently been a slight increase in the number of DCD livers transplanted in children, with satisfactory graft and patient outcomes, the use of DCD grafts in paediatric recipients is still controversial due to morbid outcomes associated with DCD grafts. In this context, recent advances in the optimization of donor support by extracorporeal membrane oxygenation and in the graft preservation by liver machine perfusion could find application in order to expand the donor pool in paediatric LT. In the present study we review the current literature on DCD liver grafts transplanted in children and on the use of extracorporeal donor support and liver perfusion machines in paediatrics, with the aim of defining the current status and future perspectives of paediatric LT.