Factors Associated With Short- and Long-term Liver Graft Survival in the United Kingdom: Development of a UK Donor Liver Index

The impact of macro- and micro-steatosis on the outcomes of patients who undergo liver transplant: Analysis of the UNOS-STAR database

BACKGROUND AND AIMS

The presence of steatosis in a donor liver and its relation to post-transplantation outcomes are not well defined. This study evaluates the effect of the presence and severity of micro- and macro-steatosis of a donor graft on post-transplantation outcomes.

METHODS

The UNOS-STAR registry (2005-2019) was used to select patients who received a liver transplant graft with hepatic steatosis. The study cohort was stratified by the presence of macro- or micro-vesicular steatosis, and further stratified by histologic grade of steatosis. The primary endpoints of all-cause mortality and graft failure were compared using sequential Cox regression analysis. Analysis of specific causes of mortality was further performed.

RESULTS

There were 9184 with no macro-steatosis (control), 150 with grade 3 macro-steatosis, 822 with grade 2 macro-steatosis and 12 585 with grade 1 macro-steatosis. There were 10 320 without micro-steatosis (control), 478 with grade 3 micro-steatosis, 1539 with grade 2 micro-steatosis and 10 404 with grade 1 micro-steatosis. There was no significant difference in all-cause mortality or graft failure among recipients who received a donor organ with any evidence of macro- or micro-steatosis, compared to those receiving non-steatotic grafts. There was increased mortality due to cardiac arrest among recipients of a grade 2 macro-steatosis donor organ.

CONCLUSION

This study shows no significant difference in all-cause mortality or graft failure among recipients who received a donor liver with any degree of micro- or macro-steatosis. Further analysis identified increased mortality due to specific aetiologies among recipients receiving donor organs with varying grades of macro- and micro-steatosis.

Current Techniques and Indications for Machine Perfusion and Regional Perfusion in Deceased Donor Liver Transplantation

Since the advent of University of Wisconsin preservation solution in the 1980s, clinicians have learned to work within its confines. While affording improved outcomes, considerable limitations still exist and contribute to the large number of livers that go unused each year, often for fear they may never work. The last 10 years have seen the widespread availability of new perfusion modalities which provide an opportunity for assessing organ viability and prolonged organ storage. This review will discuss the role of in situ normothermic regional perfusion for livers donated after circulatory death. It will also describe the different modalities of ex situ perfusion, both normothermic and hypothermic, and discuss how they are thought to work and the opportunities afforded by them.

A contemporary analysis of 20,086 deceased donor liver biopsies

BACKGROUND

Pre-transplant deceased donor liver biopsy may impact decision making; however, interpretation of the results remains variable and depends on accepting center practice patterns.

METHODS

In this cohort study, adult recipients from 04/01/2015-12/31/2020 were identified using the UNOS STARfile data. The deceased donor liver biopsies were stratified by risk based on degree of fibrosis, macrovesicular fat content, and level of portal infiltration (low-risk: no fibrosis, no portal infiltrates, and <30% macrosteatosis; moderate-risk: some fibrosis or mild infiltrates and <30% macrosteatosis; high-risk: most fibrosis, moderate/marked infiltrates, or ≥30% macrosteatosis). Graft utilization, donor risk profile, and recipient outcomes were compared across groups.

RESULTS

Of the 51,094 donor livers available, 20,086 (39.3%) were biopsied, and 34,606 (67.7%) were transplanted. Of the transplanted livers, 14,908 (43.1%) were biopsied. The transplanted grafts had lower mean macrovesicular fat content (9.3% transplanted vs. 26.9% non-transplanted, P < 0.001) and less often had any degree of fibrosis (20.9% vs. 39.9%, P < 0.001) or portal infiltration (51.3% vs. 58.2%, P < 0.001) versus non-transplanted grafts. Post-transplant recipient LOS (14.2 days high-risk vs. 15.2 days low-risk, P = 0.170) and 1-year graft survival (90.5% vs. 91.7%, P = 0.137) did not differ significantly between high- versus low-risk groups. Kaplan-Meier survival estimates further revealed no differences in the 5-year graft survival across risk strata (P = 0.833). Of the 5178 grafts biopsied and turned down, PSM revealed 1338 (26.0%) were potentially useable based on biopsy results and donor characteristics.

CONCLUSION

Carefully matched deceased donor livers with some fibrosis, inflammation, or steatosis ≥30% may be suitable for transplantation. Further study of this group of grafts may decrease turndowns of potentially useable organs.

Prognostic models: What the statistician wants the clinician to know

Prognostic model building is a process that begins much earlier than data analysis and ends later than when a model is reached. It requires careful delineation of a clinical question, methodical planning of the approach and attentive exploration of the data before attempting model building. Once following these important initial steps, the researcher may postulate a model to describe the process of interest and build such model. Once built, the model will need to be checked, validated and the exercise may take the researcher back a few steps - for instance, to adapt the model to fit a variable that displays a 'curved' pattern - to then return to check and validate the model again. To interpret and report the results it is vital to relate the output to the original question, to be transparent in the methodology followed and to understand the limitations of the data and the approach.

Donor Liver Blood Tests and Liver Transplant Outcomes: UK Registry Cohort Study

BACKGROUND

Safely increasing organ utilization is a global priority. Donor serum transaminase levels are often used to decline livers, despite minimal evidence to support such decisions. This study aimed to investigate the impact of donor "liver blood tests" on transplant outcomes.

METHODS

This retrospective cohort study used the National Health Service registry on adult liver transplantation (2016-2019); adjusted regressions models were used to assess the effect of donor "liver blood tests" on outcomes.

RESULTS

A total of 3299 adult liver transplant recipients were included (2530 following brain stem death, 769 following circulatory death). Peak alanine transaminase (ALT) ranged from 6 to 5927 U/L (median = 45). Donor cause of death significantly predicted donor ALT; 4.2-fold increase in peak ALT with hypoxic brain injury versus intracranial hemorrhage (adjusted P  < 0.001). On multivariable analysis, adjusting for a wide range of factors, transaminase level (ALT or aspartate aminotransferase) failed to predict graft survival, primary nonfunction, 90-d graft loss, or mortality. This held true in all examined subgroups, that is, steatotic grafts, donation following circulatory death, hypoxic brain injury donors, and donors, in which ALT was still rising at the time of retrieval. Even grafts from donors with extremely deranged ALT (>1000 U/L) displayed excellent posttransplant outcomes. In contrast, donor peak alkaline phosphatase was a significant predictor of graft loss (adjusted hazard ratio = 1.808; 1.016-3.216; P  = 0.044).

CONCLUSIONS

Donor transaminases do not predict posttransplant outcomes. When other factors are favorable, livers from donors with raised transaminases can be accepted and transplanted with confidence. Such knowledge should improve organ utilization decision-making and prevent future unnecessary organ discard. This provides a safe, simple, and immediate option to expand the donor pool.

Development of a liver graft assessment expert machine-learning system: when the artificial intelligence helps liver transplant surgeons

Background

The complex process of liver graft assessment is one point for improvement in liver transplantation. The main objective of this study is to develop a tool that supports the surgeon who is responsible for liver donation in the decision-making process whether to accept a graft or not using the initial variables available to it.

Material and method

Liver graft samples candidate for liver transplantation after donor brain death were studied. All of them were evaluated "in situ" for transplantation, and those discarded after the "in situ" evaluation were considered as no transplantable liver grafts, while those grafts transplanted after "in situ" evaluation were considered as transplantable liver grafts. First, a single-center, retrospective and cohort study identifying the risk factors associated with the no transplantable group was performed. Then, a prediction model decision support system based on machine learning, and using a tree ensemble boosting classifier that is capable of helping to decide whether to accept or decline a donor liver graft, was developed.

Results

A total of 350 liver grafts that were evaluated for liver transplantation were studied. Steatosis was the most frequent reason for classifying grafts as no transplantable, and the main risk factors identified in the univariant study were age, dyslipidemia, personal medical history, personal surgical history, bilirubinemia, and the result of previous liver ultrasound (p < 0.05). When studying the developed model, we observe that the best performance reordering in terms of accuracy corresponds to 76.29% with an area under the curve of 0.79. Furthermore, the model provides a classification together with a confidence index of reliability, for most cases in our data, with the probability of success in the prediction being above 0.85.

Conclusion

The tool presented in this study obtains a high accuracy in predicting whether a liver graft will be transplanted or deemed non-transplantable based on the initial variables assigned to it. The inherent capacity for improvement in the system causes the rate of correct predictions to increase as new data are entered. Therefore, we believe it is a tool that can help optimize the graft pool for liver transplantation.

Beyond donation to organ utilization in the UK

PURPOSE OF REVIEW

Optimizing deceased donor organ utilization is gaining recognition as a topical and important issue, both in the United Kingdom (UK) and globally. This review discusses pertinent issues in the field of organ utilization, with specific reference to UK data and recent developments within the UK.

RECENT FINDINGS

A multifaceted approach is likely required in order to improve organ utilization. Having a solid evidence-base upon which transplant clinicians and patients on national waiting lists can base decisions regarding organ utilization is imperative in order to bridge gaps in knowledge regarding the optimal use of each donated organ. A better understanding of the risks and benefits of the uses of higher risk organs, along with innovations such as novel machine perfusion technologies, can help clinician decision-making and may ultimately reduce the unnecessary discard of precious deceased donor organs.

SUMMARY

The issues facing the UK with regards to organ utilization are likely to be similar to those in many other developed countries. Discussions around these issues within organ donation and transplantation communities may help facilitate shared learning, lead to improvements in the usage of scarce deceased donor organs, and enable better outcomes for patients waiting for transplants.

D-dimer Release From Livers During Ex Situ Normothermic Perfusion and After In Situ Normothermic Regional Perfusion: Evidence for Occult Fibrin Burden Associated With Adverse Transplant Outcomes and Cholangiopathy

BACKGROUND

Deceased donor livers are prone to biliary complications, which may necessitate retransplantation, and we, and others, have suggested that these complications are because of peribiliary vascular fibrin microthrombi. We sought to determine the prevalence and consequence of occult fibrin within deceased donor livers undergoing normothermic ex situ perfusion (NESLiP) and evaluate a role for fibrinolysis.

METHODS

D-dimer concentrations, products of fibrin degradation, were assayed in the perfusate of 163 livers taken after 2 h of NESLiP, including 91 that were transplanted. These were related to posttransplant outcomes. Five different fibrinolytic protocols during NESLiP using alteplase were evaluated, and the transplant outcomes of these alteplase-treated livers were reviewed.

RESULTS

Perfusate D-dimer concentrations were lowest in livers recovered using in situ normothermic regional perfusion and highest in alteplase-treated livers. D-dimer release from donation after brain death livers was significantly correlated with the duration of cold ischemia. In non-alteplase-treated livers, Cox proportional hazards regression analysis showed that D-dimer levels were associated with transplant survival ( P  = 0.005). Treatment with alteplase and fresh frozen plasma during NESLiP was associated with significantly more D-dimer release into the perfusate and was not associated with excess bleeding postimplantation; 8 of the 9 treated livers were free of cholangiopathy, whereas the ninth had a proximal duct stricture.

CONCLUSIONS

Fibrin is present in many livers during cold storage and is associated with poor posttransplant outcomes. The amount of D-dimer released after fibrinolytic treatment indicates a significant occult fibrin burden and suggests that fibrinolytic therapy during NESLiP may be a promising therapeutic intervention.

Organ Transplants From Deceased Donors With Primary Brain Tumors and Risk of Cancer Transmission

Importance

Cancer transmission is a known risk for recipients of organ transplants. Many people wait a long time for a suitable transplant; some never receive one. Although patients with brain tumors may donate their organs, opinions vary on the risks involved.

Objective

To determine the risk of cancer transmission associated with organ transplants from deceased donors with primary brain tumors. Key secondary objectives were to investigate the association that donor brain tumors have with organ usage and posttransplant survival.

Design, Setting, and Participants

This was a cohort study in England and Scotland, conducted from January 1, 2000, to December 31, 2016, with follow-up to December 31, 2020. This study used linked data on deceased donors and solid organ transplant recipients with valid national patient identifier numbers from the UK Transplant Registry, the National Cancer Registration and Analysis Service (England), and the Scottish Cancer Registry. For secondary analyses, comparators were matched on factors that may influence the likelihood of organ usage or transplant failure. Statistical analysis of study data took place from October 1, 2021, to May 31, 2022.

Exposures

A history of primary brain tumor in the organ donor, identified from all 3 data sources using disease codes.

Main Outcomes and Measures

Transmission of brain tumor from the organ donor into the transplant recipient. Secondary outcomes were organ utilization (ie, transplant of an offered organ) and survival of kidney, liver, heart, and lung transplants and their recipients. Key covariates in donors with brain tumors were tumor grade and treatment history.

Results

This study included a total of 282 donors (median [IQR] age, 42 [33-54] years; 154 females [55%]) with primary brain tumors and 887 transplants from them, 778 (88%) of which were analyzed for the primary outcome. There were 262 transplants from donors with high-grade tumors and 494 from donors with prior neurosurgical intervention or radiotherapy. Median (IQR) recipient age was 48 (35-58) years, and 476 (61%) were male. Among 83 posttransplant malignancies (excluding NMSC) that occurred over a median (IQR) of 6 (3-9) years in 79 recipients of transplants from donors with brain tumors, none were of a histological type matching the donor brain tumor. Transplant survival was equivalent to that of matched controls. Kidney, liver, and lung utilization were lower in donors with high-grade brain tumors compared with matched controls.

Conclusions and Relevance

Results of this cohort study suggest that the risk of cancer transmission in transplants from deceased donors with primary brain tumors was lower than previously thought, even in the context of donors that are considered as higher risk. Long-term transplant outcomes are favorable. These results suggest that it may be possible to safely expand organ usage from this donor group.

Improved Organ Utilization and Better Transplant Outcomes With In Situ Normothermic Regional Perfusion in Controlled Donation After Circulatory Death

BACKGROUND

. We evaluated whether the use of normothermic regional perfusion (NRP) was associated with increased organ recovery and improved transplant outcomes from controlled donation after circulatory death (cDCD).

METHODS

. This is a retrospective analysis of UK adult cDCD donors' where at least 1 abdominal organ was accepted for transplantation between January 1, 2011, and December 31, 2019.

RESULTS

. A mean of 3.3 organs was transplanted when NRP was used compared with 2.6 organs per donor when NRP was not used. When adjusting for organ-specific donor risk profiles, the use of NRP increased the odds of all abdominal organs being transplanted by 3-fold for liver ( P < 0.0001; 95% confidence interval [CI], 2.20-4.29), 1.5-fold for kidney ( P = 0.12; 95% CI, 0.87-2.58), and 1.6-fold for pancreas ( P = 0.0611; 95% CI, 0.98-2.64). Twelve-mo liver transplant survival was superior for recipients of a cDCD NRP graft with a 51% lower risk-adjusted hazard of transplant failure (HR = 0.494). In risk-adjusted analyses, NRP kidneys had a 35% lower chance of developing delayed graft function than non-NRP kidneys (odds ratio, 0.65; 95% CI, 0.465-0.901)' and the expected 12-mo estimated glomerular filtration rate was 6.3 mL/min/1.73 m 2 better if abdominal NRP was used ( P < 0.0001).

CONCLUSIONS

. The use of NRP during DCD organ recovery leads to increased organ utilization and improved transplant outcomes compared with conventional organ recovery.

The positive impact of the COVID 19 pandemic on organ utilisation in liver transplantation

Background

As the world recovers from the aftermath of devastating waves of an outbreak, the ongoing Coronavirus disease 2019 pandemic has presented a unique perspective to the transplantation community of ''organ utilisation'' in liver transplantation, a poorly defined term and ongoing hurdle in this field. To this end, we report the key metrics of transplantation activity from a high-volume liver transplantation centre in the United Kingdom over the past two years.

Methods

Between March 2019 and February 2021, details of donor liver offers received by our centre from National Health Service Blood & Transplant, and of transplantation were reviewed. Differences in the activity before and after the outbreak of the pandemic, including short term post-transplant survival, have been reported.

Results

The pandemic year at our centre witnessed a higher utilisation of Donation after Cardiac Death livers (80.4% vs. 58.3%, p = 0.016) with preserved United Kingdom donor liver indices and median donor age (2.12 vs. 2.02, p = 0.638; 55 vs. 57 years, p = 0.541) when compared to the pre-pandemic year. The 1- year patient survival rates for recipients in both the periods were comparable. The pandemic year, that was associated with increased utilisation of Donation after Cardiac Death livers, had an ischaemic cholangiopathy rate of 6%.

Conclusions

The pressures imposed by the pandemic led to increased utilisation of specific donor livers to meet patient needs and minimise the risk of death on the waiting list, with apparently preserved early post-transplant survival. Optimum organ utilisation is a balancing act between risk and benefit for the potential recipient, and technologies like machine perfusion may allow surgeons to increase utilisation without compromising patient outcomes.

Predicting Early Allograft Function After Normothermic Machine Perfusion

BACKGROUND

Normothermic ex situ liver perfusion is increasingly used to assess donor livers, but there remains a paucity of evidence regarding criteria upon which to base a viability assessment or criteria predicting early allograft function.

METHODS

Perfusate variables from livers undergoing normothermic ex situ liver perfusion were analyzed to see which best predicted the Model for Early Allograft Function score.

RESULTS

One hundred fifty-four of 203 perfused livers were transplanted following our previously defined criteria. These comprised 84/123 donation after circulatory death livers and 70/80 donation after brain death livers. Multivariable analysis suggested that 2-h alanine transaminase, 2-h lactate, 11 to 29 mmol supplementary bicarbonate in the first 4 h, and peak bile pH were associated with early allograft function as defined by the Model for Early Allograft Function score. Nonanastomotic biliary strictures occurred in 11% of transplants, predominantly affected first- and second-order ducts, despite selection based on bile glucose and pH.

CONCLUSIONS

This work confirms the importance of perfusate alanine transaminase and lactate at 2-h, as well as the amount of supplementary bicarbonate required to keep the perfusate pH > 7.2, in the assessment of livers undergoing perfusion. It cautions against the use of lactate as a sole indicator of viability and also suggests a role for cholangiocyte function markers in predicting early allograft function.

Development of a risk score model for 1-year graft loss after adult deceased donor liver transplantation in Japan based on a 20-year nationwide cohort

Aim

Using nationwide data collected over the past 20 years, we aimed to investigate deceased donor liver transplantation (DDLT) outcomes to develop a unique risk model that can be used to establish a standard for organ acceptance in Japan.

Methods

Data were collected for 449 recipients aged ≥18 years who underwent DDLT between 1999 and 2019. Least absolute shrinkage and selection operator (LASSO) regression analysis was utilized to develop an original risk score model for 1-year graft loss (termed the Japan Risk Index [JRI]). We developed risk indices according to recipient, donor, and surgery components (termed JRI-R, D, and S, respectively). The JRI was validated via a 5-fold cross-validation. We also compared DDLT outcomes and risk indices among Era1 (-2011), Era2 (-2015), and Era3 (-2019).

Results

The 1-year graft survival rate was 89.5% and improved significantly, reaching 84.7%, 87.6%, and 93.9% in Era1, Era2, and Era3, respectively. The JRI was calculated as JRI-R (re-transplantation, Model for End-Stage Liver Disease score, medical condition in intensive care unit) × JRI-D (age, catecholamine index, maximum sodium, maximum total bilirubin) × JRI-S (total ischemic time) × 0.84. The risk model achieved a mean C-statistic value of 0.81 in the validation analysis. The risk index was significantly lower in Era3 than in Era2.

Conclusion

Changes in the risk index over time indicated that avoiding risks contributed to the improved outcomes in Era3. The JRI is unique to adult DDLT in Japan and may be useful as a reference for organ acceptance in the future.

Normothermic Machine Perfusion—Improving the Supply of Transplantable Livers for High-Risk Recipients

The effectiveness of liver transplantation to cure numerous diseases, alleviate suffering, and improve patient survival has led to an ever increasing demand. Improvements in preoperative management, surgical technique, and postoperative care have allowed increasingly complicated and high-risk patients to be safely transplanted. As a result, many patients are safely transplanted in the modern era that would have been considered untransplantable in times gone by. Despite this, more gains are possible as the science behind transplantation is increasingly understood. Normothermic machine perfusion of liver grafts builds on these gains further by increasing the safe use of grafts with suboptimal features, through objective assessment of both hepatocyte and cholangiocyte function. This technology can minimize cold ischemia, but prolong total preservation time, with particular benefits for suboptimal grafts and surgically challenging recipients. In addition to more physiological and favorable preservation conditions for grafts with risk factors for poor outcome, the extended preservation time benefits operative logistics by allowing a careful explant and complicated vascular reconstruction when presented with challenging surgical scenarios. This technology represents a significant advancement in graft preservation techniques and the transplant community must continue to incorporate this technology to ensure the benefits of liver transplant are maximized.

Disparities in the Use of Older Donation After Circulatory Death Liver Allografts in the United States Versus the United Kingdom

BACKGROUND

This study aimed to assess the differences between the United States and the United Kingdom in the characteristics and posttransplant survival of patients who received donation after circulatory death (DCD) liver allografts from donors aged >60 y.

METHODS

Data were collected from the UK Transplant Registry and the United Network for Organ Sharing databases. Cohorts were dichotomized into donor age subgroups (donor >60 y [D >60]; donor ≤60 y [D ≤60]). Study period: January 1, 2001, to December 31, 2015.

RESULTS

1157 DCD LTs were performed in the United Kingdom versus 3394 in the United States. Only 13.8% of US DCD donors were aged >50 y, contrary to 44.3% in the United Kingdom. D >60 were 22.6% in the United Kingdom versus 2.4% in the United States. In the United Kingdom, 64.2% of D >60 clustered in 2 metropolitan centers. In the United States, there was marked inter-regional variation. A total of 78.3% of the US DCD allografts were used locally. One- and 5-y unadjusted DCD graft survival was higher in the United Kingdom versus the United States (87.3% versus 81.4%, and 78.0% versus 71.3%, respectively; P < 0.001). One- and 5-y D >60 graft survival was higher in the United Kingdom (87.3% versus 68.1%, and 77.9% versus 51.4%, United Kingdom versus United States, respectively; P < 0.001). In both groups, grafts from donors ≤30 y had the best survival. Survival was similar for donors aged 41 to 50 versus 51 to 60 in both cohorts.

CONCLUSIONS

Compared with the United Kingdom, older DCD LT utilization remained low in the United States, with worse D >60 survival. Nonetheless, present data indicate similar survivals for older donors aged ≤60, supporting an extension to the current US DCD age cutoff.

Normothermic Machine Perfusion as a Tool for Safe Transplantation of High-Risk Recipients

Normothermic machine perfusion (NMP) should no longer be considered a novel liver graft preservation strategy, but rather viewed as the standard of care for certain graft–recipient scenarios. The ability of NMP to improve the safe utilisation of liver grafts has been demonstrated in several publications, from numerous centres. This is partly mediated by its ability to limit the cold ischaemic time while also extending the total preservation period, facilitating the difficult logistics of a challenging transplant operation. Viability assessment of both the hepatocytes and cholangiocytes with NMP is much debated, with numerous different parameters and thresholds associated with a reduction in the incidence of primary non-function and biliary strictures. Maximising the utilisation of liver grafts is important as many patients require transplantation on an urgent basis, the waiting list is long, and significant morbidity and mortality is experienced by patients awaiting transplants. If applied in an appropriate manner, NMP has the ability to expand the pool of grafts available for even the sickest and most challenging of recipients. In addition, this is the group of patients that consume significant healthcare resources and, therefore, justify the additional expense of NMP. This review describes, with case examples, how NMP can be utilised to salvage suboptimal grafts, and our approach of transplanting them into high-risk recipients.

Introduction of the Concept of Diagnostic Sensitivity and Specificity of Normothermic Perfusion Protocols to Assess High-Risk Donor Livers

Normothermic machine perfusion (NMP) allows objective assessment of donor liver transplantability. Several viability evaluation protocols have been established, consisting of parameters such as perfusate lactate clearance, pH, transaminase levels, and the production and composition of bile. The aims of this study were to assess 3 such protocols, namely, those introduced by the teams from Birmingham (BP), Cambridge (CP), and Groningen (GP), using a cohort of high-risk marginal livers that had initially been deemed unsuitable for transplantation and to introduce the concept of the viability assessment sensitivity and specificity. To demonstrate and quantify the diagnostic accuracy of these protocols, we used a composite outcome of organ use and 24-month graft survival as a surrogate endpoint. The effects of assessment modifications, including the removal of the most stringent components of the protocols, were also assessed. Of the 31 organs, 22 were transplanted after a period of NMP, of which 18 achieved the outcome of 24-month graft survival. The BP yielded 94% sensitivity and 50% specificity when predicting this outcome. The GP and CP both seemed overly conservative, with 1 and 0 organs, respectively, meeting these protocols. Modification of the GP and CP to exclude their most stringent components increased this to 11 and 8 organs, respectively, and resulted in moderate sensitivity (56% and 44%) but high specificity (92% and 100%, respectively) with respect to the composite outcome. This study shows that the normothermic assessment protocols can be useful in identifying potentially viable organs but that the balance of risk of underuse and overuse varies by protocol.

Development of a Novel Prognostic Nomogram for High Model for End-Stage Liver Disease Score Recipients Following Deceased Donor Liver Transplantation

Background

A high model of end-stage liver disease (MELD) score (>30) adversely affects outcomes even if patients receive prompt liver transplantation (LT). Therefore, balanced allocation of donor grafts is indispensable to avoid random combinations of donor and recipient risk factors, which often lead to graft or recipient loss. Predictive models aimed at avoiding donor risk factors in high-MELD score recipients are urgently required to obtain satisfactory outcomes.

Method

Data of patients with MELD score >30 who underwent LT at three transplantation institutes between 2015 and 2018 were retrospectively reviewed. Early allograft dysfunction (EAD), length of intensive care unit (ICU) stay, and graft loss were recorded. Corresponding independent risk factors were analyzed using stepwise multivariable regression analysis. A prediction model of graft loss was developed, and discrimination and calibration were measured.

Results

After applying the exclusion criteria, 778 patients were enrolled. The incidence of EAD was 34.8% (271/778). Donor graft macrovesicular steatosis, graft-to-recipient weight ratio (GRWR), warm ischemia time (WIT), cold ischemia time (CIT), and ABO blood incompatibility, together with donor serum albumins, were independent predictors of EAD. The incidence of ICU stay over 10 days was 64.7% (503/778). Donor age, recipient's MELD score, Child score, and CIT were independent predictors of ICU stay. The 3-year graft survival rates (GSRs) in the training and validation cohorts were 64.2 and 59.3%, respectively. The independent predictors of graft loss were recipient's Child score, ABO blood type incompatibility, donor serum total bilirubin over 17.1 μmol/L, and cold CIT. A nomogram based on these variables was internally and externally validated and showed good performance (area under the receiver operating characteristic curve = 70.8 and 66.0%, respectively). For a recipient with a high MELD score, the avoidance of ABO blood type incompatibility and CIT ≥6 h would achieve a 3-year GSR of up to 78.4%, whereas the presence of the aforementioned risk factors would decrease the GSR to 35.4%.

Conclusion

The long-term prognosis of recipients with MELD scores >30 could be greatly improved by avoiding ABO blood type incompatibility and CIT ≥6 h.

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.

Liver Transplantation Outcomes From Controlled Circulatory Death Donors: Static cold storage vs in situ normothermic regional perfusion vs ex situ normothermic machine perfusion

OBJECTIVE

To compare the outcomes of livers donated after circulatory death (DCD) and undergoing either in situ normothermic regional perfusion (NRP) or ex situ normothermic machine perfusion (NMP) with livers undergoing static cold storage (SCS).

SUMMARY OF BACKGROUND DATA

DCD livers are associated with increased risk of primary nonfunction, poor function, and nonanastomotic strictures (NAS), leading to underutilization.

METHODS

A single center, retrospective analysis of prospectively collected data on 233 DCD liver transplants performed using SCS, NRP, or NMP between January 2013 and October 2020.

RESULTS

Ninety-seven SCS, 69 NRP, and 67 NMP DCD liver transplants were performed, with 6-month and 3-year transplant survival (graft survival noncensored for death) rates of 87%, 94%, 90%, and 76%, 90%, and 76%, respectively. NRP livers had a lower 6-month risk-adjusted Cox proportional hazard for transplant failure compared to SCS (hazard ratio 0.30, 95%CI 0.08-1.05, P = 0.06). NRP and NMP livers had a risk-adjusted estimated reduction in the mean model for early allograft function score of 1.52 (P < 0.0001) and 1.19 (P < 0.001) respectively compared to SCS. Acute kidney injury was more common with SCS (55% vs 39% NRP vs 40% NMP; P = 0.08), with a lower risk-adjusted peak-to-baseline creatinine ratio in the NRP (P = 0.02). No NRP liver had clinically significant NAS in contrast to SCS (14%) and NMP (11%, P = 0.009), with lower risk-adjusted odds of overall NAS development compared to SCS (odds ratio = 0.2, 95%CI 0.06-0.72, P = 0.01).

CONCLUSION

NRP and NMP were associated with better early liver function compared to SCS, whereas NRP was associated with superior preservation of the biliary system.

A coordinated national UK liver transplant program response, prioritising waitlist recipients with the highest need, provided excellent outcomes during the first wave of the COVID-19 pandemic

Healthcare provision has been severely affected by COVID-19, with specific challenges in organ transplantation. Here, we describe the coordinated response to, and outcomes during the first wave, across all UK liver transplant (LT) centres. Several policy changes affecting the liver transplant processes were agreed upon. These included donor age restrictions and changes to offering. A 'high-urgency' (HU) category was established, prioritising only those with UKELD >60, HCC reaching transplant criteria, and others likely to die within 90 days. Outcomes were compared with the same period in 2018 & 2019. The retrieval rate for deceased donor livers (71% vs 54%; p<0.0001) and conversion from offer to completed transplant (63% vs 48%; p<0.0001) was significantly higher. Paediatric LT activity was maintained; there was a significant reduction in adult (42%) and total (36%) LT. Almost all adult LT were super-urgent (n = 15) or HU (n = 133). We successfully prioritised those with highest illness severity with no reduction in 90-day patient (p = 0.89) or graft survival (p = 0.98). There was a small (5% compared with 3%; p = 0.0015) increase in deaths or removals from the waitlist, mainly amongst HU cohort. We successfully prioritised LT recipients in highest need, maintaining excellent outcomes, and waitlist mortality was only marginally increased. This article is protected by copyright. All rights reserved.

Protocol for a prospective double-blind, randomised, placebo-controlled feasibility trial of octreotide infusion during liver transplantation

INTRODUCTION

Liver transplantation is a complex operation that can provide significant improvements in quality of life and survival to the recipients. However, serious complications are common and include major haemorrhage, hypotension and renal failure. Blood transfusion and the development of acute kidney injury lead to both short-term and long-term poor patient outcomes, including an increased risk of death, graft failure, length of stay and reduced quality of life. Octreotide may reduce the incidence of renal dysfunction, perioperative haemorrhage and enhance intraoperative blood pressure. However, octreotide does have risks, including resistant bradycardia, hyperglycaemia and hypoglycaemia and QT prolongation. Hence, a randomised controlled trial of octreotide during liver transplantation is needed to determine the cost-efficacy and safety of its use; this study represents a feasibility study prior to this trial.

METHODS AND ANALYSIS

We describe a multicentre, double-blind, randomised, placebo-controlled feasibility study of continuous infusion of octreotide during liver transplantation surgery. We will recruit 30 adult patients at two liver transplant centres. A blinded infusion during surgery will be administered in a 2:1 ratio of octreotide:placebo. The primary outcomes will determine the feasibility of this study design. These include the recruitment ratio, correct administration of blinded study intervention, adverse event rates, patient and clinician enrolment refusal and completion of data collection. Secondary outcome measures of efficacy and safety will help shape future trials by assessing potential primary outcome measures and monitoring safety end points. No formal statistical tests are planned. This manuscript represents study protocol number 1.3, dated 2 June 2021.

ETHICS AND DISSEMINATION

This study has received Research Ethics Committee approval. The main study outcomes will be submitted to an open-access journal.

TRIAL SPONSOR

The Joint Research Office, University College London, UK.Neither the sponsor nor the funder have any role in study design, collection, management, analysis and interpretation of data, writing of the study report or the decision to submit the report for publication.

TRIAL REGISTRATION

The study is registered with ClinicalTrials.gov (NCT04941911) with recruitment due to start in August 2021 with anticipated completion in July 2022.

CLINICAL TRIALS UNIT

Surgical and Interventional Group, Division of Surgery & Interventional Science, University College London.

National time trends in mortality and graft survival following liver transplantation from circulatory death or brainstem death donors

BACKGROUND

Despite high waiting list mortality rates, concern still exists on the appropriateness of using livers donated after circulatory death (DCD). We compared mortality and graft loss in recipients of livers donated after circulatory or brainstem death (DBD) across two successive time periods.

METHODS

Observational multinational data from the United Kingdom and Ireland were partitioned into two time periods (2008-2011 and 2012-2016). Cox regression methods were used to estimate hazard ratios (HRs) comparing the impact of periods on post-transplant mortality and graft failure.

RESULTS

A total of 1176 DCD recipients and 3749 DBD recipients were included. Three-year patient mortality rates decreased markedly from 19.6 per cent in time period 1 to 10.4 per cent in time period 2 (adjusted HR 0.43, 95 per cent c.i. 0.30 to 0.62; P < 0.001) for DCD recipients but only decreased from 12.8 to 11.3 per cent (adjusted HR 0.96, 95 per cent c.i. 0.78 to 1.19; P = 0.732) in DBD recipients (P for interaction = 0.001). No time period-specific improvements in 3-year graft failure were observed for DCD (adjusted HR 0.80, 95% c.i. 0.61 to 1.05; P = 0.116) or DBD recipients (adjusted HR 0.95, 95% c.i. 0.79 to 1.14; P = 0.607). A slight increase in retransplantation rates occurred between time period 1 and 2 in those who received a DCD liver (from 7.3 to 11.8 per cent; P = 0.042), but there was no change in those receiving a DBD liver (from 4.9 to 4.5 per cent; P = 0.365). In time period 2, no difference in mortality rates between those receiving a DCD liver and those receiving a DBD liver was observed (adjusted HR 0.78, 95% c.i. 0.56 to 1.09; P = 0.142).

CONCLUSION

Mortality rates more than halved in recipients of a DCD liver over a decade and eventually compared similarly to mortality rates in recipients of a DBD liver. Regions with high waiting list mortality may mitigate this by use of DCD livers.

Inferior outcomes in young adults undergoing liver transplantation - a UK and Ireland cohort study

Graft loss incidence is reported to be inversely related to recipient age. We used a national cohort of liver transplant (LT) recipients from the United Kingdom and Ireland to compare the age-dependent risk of graft failure in different post-transplantation time-periods ('epochs'). A cohort of first-time LT recipients (1995-2016) were identified (11 006). Cox regression was used to estimate hazard ratios (HR) comparing graft loss between age-groups (18-29, 30-39, 40-49, 50-59 and 60-76 years) and graft loss in different post-transplant epochs: 0-90 days, 90 days-2 years and 2-10 years. The risk of graft failure was highest in those transplanted between age 18 and 29 (adjusted HR 1.25, 95% CI: 1.00-1.57, P = 0.04) and in those aged 30-39 (adjusted HR 1.31, 95% CI: 1.11-1.55, P = 0.02). Graft failure in those under the age of 40 was similar in the first 90 days but worse 2-10 years' post-LT (18-29 years HR 1.36, 95% CI: 0.96-1.93, P < 0.001). Graft failure because of chronic rejection (CR) was more common in recipients aged 18-29 (P < 0.001). Adults transplanted between age 18 and 39 are at risk of late graft loss. CR is a concern for young adults (18-29 years). Our data highlights the need for specialist young adult services within adult healthcare.

Mitochondrial respiratory chain and Krebs cycle enzyme function in human donor livers subjected to end-ischaemic hypothermic machine perfusion

INTRODUCTION

Marginal human donor livers are highly susceptible to ischaemia reperfusion injury and mitochondrial dysfunction. Oxygenation during hypothermic machine perfusion (HMP) was proposed to protect the mitochondria but the mechanism is unclear. Additionally, the distribution and uptake of perfusate oxygen during HMP are unknown. This study aimed to examine the feasibility of mitochondrial function analysis during end-ischaemic HMP, assess potential mitochondrial viability biomarkers, and record oxygenation kinetics.

METHODS

This was a randomised pilot study using human livers retrieved for transplant but not utilised. Livers (n = 38) were randomised at stage 1 into static cold storage (n = 6), hepatic artery HMP (n = 7), and non-oxygen supplemented portal vein HMP (n = 7) and at stage 2 into oxygen supplemented and non-oxygen supplemented portal vein HMP (n = 11 and 7, respectively). Mitochondrial parameters were compared between the groups and between low- and high-risk marginal livers based on donor history, organ steatosis and preservation period. The oxygen delivery efficiency was assessed in additional 6 livers using real-time measurements of perfusate and parenchymal oxygen.

RESULTS

The change in mitochondrial respiratory chain (complex I, II, III, IV) and Krebs cycle enzyme activity (aconitase, citrate synthase) before and after 4-hour preservation was not different between groups in both study stages (p > 0.05). Low-risk livers that could have been used clinically (n = 8) had lower complex II-III activities after 4-hour perfusion, compared with high-risk livers (73 nmol/mg/min vs. 113 nmol/mg/min, p = 0.01). Parenchymal pO2 was consistently lower than perfusate pO2 (p ≤ 0.001), stabilised in 28 minutes compared to 3 minutes in perfusate (p = 0.003), and decreased faster upon oxygen cessation (75 vs. 36 minutes, p = 0.003).

CONCLUSIONS

Actively oxygenated and air-equilibrated end-ischaemic HMP did not induce oxidative damage of aconitase, and respiratory chain complexes remained intact. Mitochondria likely respond to variable perfusate oxygen levels by adapting their respiratory function during end-ischaemic HMP. Complex II-III activities should be further investigated as viability biomarkers.

Effluent Molecular Analysis Guides Liver Graft Allocation to Clinical Hypothermic Oxygenated Machine Perfusion

Hypothermic-oxygenated-machine-perfusion (HOPE) allows assessment/reconditioning of livers procured from high-risk donors before transplantation. Graft referral to HOPE mostly depends on surgeons' subjective judgment, as objective criteria are still insufficient. We investigated whether analysis of effluent fluids collected upon organ flush during static-cold-storage can improve selection criteria for HOPE utilization. Effluents were analyzed to determine cytolysis enzymes, metabolites, inflammation-related mediators, and damage-associated-molecular-patterns. Molecular profiles were assessed by unsupervised cluster analysis. Differences between "machine perfusion (MP)-yes" vs. "MP-no"; "brain-death (DBD) vs. donation-after-circulatory-death (DCD)"; "early-allograft-dysfunction (EAD)-yes" vs. "EAD-no" groups, as well as correlation between effluent variables and transplantation outcome, were investigated. Livers assigned to HOPE (n = 18) showed a different molecular profile relative to grafts transplanted without this procedure (n = 21, p = 0.021). Increases in the inflammatory mediators PTX3 (p = 0.048), CXCL8/IL-8 (p = 0.017), TNF-α (p = 0.038), and ANGPTL4 (p = 0.010) were observed, whereas the anti-inflammatory cytokine IL-10 was reduced (p = 0.007). Peculiar inflammation, cell death, and coagulation signatures were observed in fluids collected from DCD livers compared to those from DBD grafts. AST (p = 0.034), ALT (p = 0.047), and LDH (p = 0.047) were higher in the "EAD-yes" compared to the "EAD-no" group. Cytolysis markers and hyaluronan correlated with recipient creatinine, AST, and ICU stay. The study demonstrates that effluent molecular analysis can provide directions about the use of HOPE.

A review of split liver transplantation with full right/left hemi-liver grafts for 2 adult recipients

Liver transplantation has become a routine operation in many transplantation centers worldwide. However, liver graft availability fails to meet patient demands. Split liver transplantation (SPLT), which divides a deceased donor liver into 2 partial liver grafts, is a promising strategy for increasing graft availability for transplantation and ameliorating organ shortage to a certain degree. However, the transplantation community has not yet reached a consensus on SPLT because of the variable results. Specifically, SPLT for 2 adult recipients using full right/left hemi-liver grafts is clinically more challenging in terms of surgical technique and potential postoperative complications. Therefore, this review summarizes the current status of SPLT, focusing on the transplantation of adult recipients. Furthermore, the initiation of the SPLT program, donor allocation, surgical aspects, recipient outcomes, and obstacles to developing this procedure will be thoroughly discussed. This information might help provide an optimal strategy for implementing SPLT for 2 adult recipients among current transplantation societies. Meanwhile, potential obstacles to SPLT might be overcome in the near future with growing knowledge, experience, and refinement of surgical techniques. Ultimately, the widespread diffusion of SPLT may increase graft availability and mitigate organ donation shortages.

Recommendations for Donor and Recipient Selection and Risk Prediction: Working Group Report From the ILTS Consensus Conference in DCD Liver Transplantation

Although the utilization of donation after circulatory death donors (DCDs) for liver transplantation (LT) has increased steadily, much controversy remains, and no common acceptance criteria exist with regard to donor and recipient risk factors and prediction models. A consensus conference was organized by International Liver Transplantation Society on January 31, 2020, in Venice, Italy, to review the current clinical practice worldwide regarding DCD-LT and to develop internationally accepted guidelines. The format of the conference was based on the grade system. International experts in this field were allocated to 6 working groups and prepared evidence-based recommendations to answer-specific questions considering the currently available literature. Working group members and conference attendees served as jury to edit and confirm the final recommendations presented at the end of the conference by each working group separately. This report presents the final statements and recommendations provided by working group 2, covering the entire spectrum of donor and recipient risk factors and prediction models in DCD-LT.

Comparable graft survival is achievable with the usage of donation after circulatory death liver grafts from donors at or above 70 years of age: A long-term UK national analysis

The aim of the study was to assess the UK donation after circulatory death (DCD) liver transplant experience from donors ≥70 years. Nationwide UK DCD retrospective analysis was conducted between 2001 and 2015 (n = 1163). Recipients were divided into group 1 vs. group 2 (donors 70≥ vs. <70 years, respectively). group 1 (n = 69, 5.9%) recipients were older (median 59 vs. 55 years, p = .001) and had longer waitlist time (128 vs. 84 days; p = .039). 94.2% of group 1 clustered in London and Birmingham, where the two busiest centers are located. group 1 allografts had higher UKDRI and UK DCD Risk Scores but similar WIT and CIT and were more likely to have been imported. Both groups had similar 1-, 3-, and 5-year graft survival (group 1, 90%, 81.4%, and 74% vs. group 2, 88.6%, 81.4%, and 78.6%, respectively; p = .54). Both groups had similar ICU stay length (p = .22), 3-month hepatic artery thrombosis rates (4.4% vs 4.0%; p = .9), and 12-month readmission rates for all biliary complications (20.3% vs 25.7%; p = .32). This study demonstrates that acceptable outcomes are achievable using older grafts in a highly selected cohort at experienced centers. Advanced age should not be an absolute contraindication to utilizing a DCD graft from donors aged ≥70 years.

Combining Donor and Recipient Age With Preoperative MELD and UKELD Scores for Predicting Survival After Liver Transplantation

OBJECTIVES

The end-stage liver disease scoring systems MELD, UKELD, and D-MELD (donor age × MELD) have had mediocre results for survival assessment after orthotopic liver transplant. Here, we introduced new indices based on preoperative MELD and UKELDscores and assessed their predictive ability on survival posttransplant.

MATERIALS AND METHODS

We included 1017 deceased donor orthotopic liver transplants that were performed between 2008 (the year UKELD was introduced) and 2019. Donor and recipient characteristics, liver disease scores, transplant characteristics, and outcomes were collected for analyses. D-MELD, D-UKELD (donor age × UKELD),DR-MELD[(donor age + recipient age) × MELD], and DR-UKELD [(donor age + recipient age) × UKELD] were calculated.

RESULTS

No score had predictive value for graft survival. For patient survival,DR-MELD and DR-UKELD provided the best results but with low accuracy. The highest accuracy was observed at 1 year posttransplant (areas under the curve of 0.598 [95% CI, 0.529-0.667] and 0.609 [95% CI, 0.549-0.67]forDR-MELDandDR-UKELD). Addition of donor and recipient age significantly improved the predictive abilities of MELD and UKELD for patient survival, but addition of donor age alone did not. For 1-year mortality (using receiver operating characteristic curves), optimal cut-off points were DR-MELD>2345 and DR-UKELD>5908. Recipients with DR-MELD >2345 (P < .001) and DR-UKELD >5908 (P = .002) had worse patient survival within the first year, but only DR-MELD >2345 remained significant after multivariable analysis (P = .007).

CONCLUSIONS

DR-MELD and DR-UKELD scores provided the best, albeit mediocre, predictive ability among the 6 tested models, especially at 1 year after posttransplant, although only for patient but not for graft survival. A DR-MELD >2345 was considered to be an additional independent risk factor for worse recipient survival within the first postoperative year.

Trials & Tribulations of Liver Transplantation- are trials now prohibitive without surrogate endpoints?

During the past 5 decades, liver transplantation has moved from its pioneering days where success was measured in days to a point where it is viewed as a routine part of medical care. Despite this progress, there are still significant unmet needs and outstanding questions that need addressing in clinical trials to improve outcomes for patients. The traditional endpoint for trials in liver transplantation has been 1-year patient survival, but with rates now approaching 95%, this endpoint now poses a number of significant financial and logistical barriers to conducting trials because of the large numbers of participants required to demonstrate only an incremental improvement. Here, we suggest the following solutions to this challenge: adoption of validated surrogate endpoints; bigger and better collaborative multiarm, multiphase studies; recognition by funders and institutions that work on larger collaborative research projects is potentially more important than smaller, self-led bodies of work; ringfenced areas of research within trial frameworks where individuals can take a lead; and fair funding structures using both industry and public sector money across national and international borders.

Risk factors and impact of early anastomotic biliary complications after liver transplantation: UK registry analysis

Background

Biliary leaks and anastomotic strictures are common early anastomotic biliary complications (EABCs) following liver transplantation. However, there are no large multicentre studies investigating their clinical impact or risk factors. This study aimed to define the incidence, risk factors and impact of EABC.

Methods

The NHS registry on adult liver transplantation between 2006 and 2017 was reviewed retrospectively. Adjusted regression models were used to assess predictors of EABC, and their impact on outcomes.

Results

Analyses included 8304 liver transplant recipients. Patients with EABC (9·6 per cent) had prolonged hospitalization (23 versus 15 days; P < 0·001) and increased chance for readmission within the first year (56 versus 32 per cent; P < 0·001). Patients with EABC had decreased estimated 5-year graft survival of 75·1 versus 84·5 per cent in those without EABC, and decreased 5-year patient survival of 76·9 versus 83·3 per cent; both P < 0.001. Adjusted Cox regression revealed that EABCs have a significant and independent impact on graft survival (leak hazard ratio (HR) 1·344, P = 0·015; stricture HR 1·513, P = 0·002; leak plus stricture HR 1·526, P = 0·036) and patient survival (leak HR 1·215, P = 0·136, stricture HR 1·526, P = 0·001; leak plus stricture HR 1·509; P = 0·043). On adjusted logistic regression, risk factors for EABC included donation after circulatory death grafts, graft aberrant arterial anatomy, biliary anastomosis type, vascular anastomosis time and recipient model of end-stage liver disease.

Conclusion

EABCs prolong hospital stay, increase readmission rates and are independent risk factors for graft loss and increased mortality. This study has identified factors that increase the likelihood of EABC occurrence; research into interventions to prevent EABCs in these at-risk groups is vital to improve liver transplantation outcomes.

Pilot study of a noninvasive real-time optical backscatter probe in liver transplantation

Transplantation of severely steatotic donor livers is associated with early allograft dysfunction and poorer graft survival. Histology remains the gold standard diagnostic of donor steatosis despite the lack of consensus definition and its subjective nature. In this prospective observational study of liver transplant patients, we demonstrate the feasibility of using a handheld optical backscatter probe to assess the degree of hepatic steatosis and correlate the backscatter readings with clinical outcomes. The probe is placed on the surface of the liver and emits red and near infrared light from the tip of the device and measures the amount of backscatter of light from liver tissue via two photodiodes. Measurement of optical backscatter (Mantel-Cox P < 0.0001) and histopathological scoring of macrovesicular steatosis (Mantel-Cox P = 0.046) were predictive of 5-year graft survival. Recipients with early allograft dysfunction defined according to both Olthoff (P = 0.0067) and MEAF score (P = 0.0097) had significantly higher backscatter levels from the donor organ. Backscatter was predictive of graft loss (AUC 0.75, P = 0.0045). This study demonstrates the feasibility of real-time measurement of optical backscatter in donor livers. Early results indicate readings correlate with steatosis and may give insight to graft outcomes such as early allograft dysfunction and graft loss.

Organ donation and transplantation: a multi-stakeholder call to action

Although overall donation and transplantation activity is higher in Europe than on other continents, differences between European countries in almost every aspect of transplantation activity (for example, in the number of transplantations, the number of people with a functioning graft, in rates of living versus deceased donation, and in the use of expanded criteria donors) suggest that there is ample room for improvement. Herein we review the policy and clinical measures that should be considered to increase access to transplantation and improve post-transplantation outcomes. This Roadmap, generated by a group of major European stakeholders collaborating within a Thematic Network, presents an outline of the challenges to increasing transplantation rates and proposes 12 key areas along with specific measures that should be considered to promote transplantation. This framework can be adopted by countries and institutions that are interested in advancing transplantation, both within and outside the European Union. Within this framework, a priority ranking of initiatives is suggested that could serve as the basis for a new European Union Action Plan on Organ Donation and Transplantation.

Research progress on hepatic machine perfusion

Nowadays, liver transplantation is the most effective treatment for end-stage liver disease. However, the increasing imbalance between growing demand for liver transplantation and the shortage of donor pool restricts the development of liver transplantation. How to expand the donor pool is a significant problem to be solved clinically. Many doctors have devoted themselves to marginal grafting, which introduces livers with barely passable quality but a high risk of transplant failure into the donor pool. However, existing common methods of preserving marginal grafts lead to both high risk of postoperative complications and high mortality. The application of machine perfusion allows surgeons to make marginal livers meet the standard criteria for transplant, which shows promising prospect in preserving and repairing donor livers and improving ischemia reperfusion injury. This review summarizes the progress of recent researches on hepatic machine perfusion.

Impact of donor smoking history on post heart transplant outcomes: A propensity-matched analysis of ISHLT registry

PURPOSE

Smoking is a major public health issue, and its effect on cardiovascular outcomes is well established. This study evaluates the impact of donor smoking on heart transplant (HT) outcomes.

METHODS

HT recipients between January 1, 2005, and December 31, 2016, with known donor smoking status were queried from the International Society of Heart and Lung Transplantation (ISHLT) registry. The primary outcome was all-cause mortality, and secondary endpoints were graft failure, acute rejection, and cardiac allograft vasculopathy. We utilized propensity-score matching to identify cohorts of recipients with and without a history of donor smoking. Hazard ratios for post-transplant outcomes for the matched sample were estimated from separate Cox proportional hazard models.

RESULTS

Of 26 390 patients in the cohort, 18.9% had history of donor smoking. Donors with history of smoking were older, predominantly male and had higher incidence of diabetes, hypertension, cocaine use, and "high-risk" status. In propensity-matched analysis, recipients with a history of donor smoking had increased risk of death (HR 1.11, 95% CI 1.03-1.20) and higher risk of graft failure (HR 1.11, 95% CI 1.03-1.20).

CONCLUSION

Donor smoking was associated with increased mortality and higher incidence of graft failure following HT. Consideration of donor smoking history is warranted while evaluating donor hearts.

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.

Sirtuin-1 expression and activity is diminished in aged liver grafts

The cellular mechanisms underlying impaired function of aged liver grafts have not been fully elucidated, but mitochondrial dysfunction appears to be contributory. Sirtuin1 has been identified as a key mediator of mitochondrial recovery following ischemia-reperfusion injury. The purpose of this study was to determine whether differences exist in sirtuin-1 expression/activity in old vs. young liver grafts and to determine correlations with mitochondrial function, graft metabolic function, and graft injury. Old and young rat liver grafts (N = 7 per group) were exposed to 12 h of static cold storage (SCS), followed by a 2 h period of graft reperfusion ex vivo. Sirtuin1 expression and activity, mitochondrial function, graft metabolic function, and graft injury were compared. Sirtuin1 expression is upregulated in young, but not old, liver grafts in response to cold storage and reperfusion. This is associated with diminished tissue ATP, antioxidant defense, and graft metabolic function in old liver grafts. There was no evidence of increased inflammation or histologic injury in old grafts. Sirtuin1 expression is diminished in old liver grafts and correlates with mitochondrial and metabolic function. The sirtuin pathway may represent a target for intervention to enhance the function of aged liver grafts.

Using Artificial Intelligence for Predicting Survival of Individual Grafts in Liver Transplantation: A Systematic Review

The demand for liver transplantation far outstrips the supply of deceased donor organs, and so, listing and allocation decisions aim to maximize utility. Most existing methods for predicting transplant outcomes use basic methods, such as regression modeling, but newer artificial intelligence (AI) techniques have the potential to improve predictive accuracy. The aim was to perform a systematic review of studies predicting graft outcomes following deceased donor liver transplantation using AI techniques and to compare these findings to linear regression and standard predictive modeling: donor risk index (DRI), Model for End-Stage Liver Disease (MELD), and Survival Outcome Following Liver Transplantation (SOFT). After reviewing available article databases, a total of 52 articles were reviewed for inclusion. Of these articles, 9 met the inclusion criteria, which reported outcomes from 18,771 liver transplants. Artificial neural networks (ANNs) were the most commonly used methodology, being reported in 7 studies. Only 2 studies directly compared machine learning (ML) techniques to liver scoring modalities (i.e., DRI, SOFT, and balance of risk [BAR]). Both studies showed better prediction of individual organ survival with the optimal ANN model, reporting an area under the receiver operating characteristic curve (AUROC) 0.82 compared with BAR (0.62) and SOFT (0.57), and the other ANN model gave an AUC ROC of 0.84 compared with a DRI (0.68) and SOFT (0.64). AI techniques can provide high accuracy in predicting graft survival based on donors and recipient variables. When compared with the standard techniques, AI methods are dynamic and are able to be trained and validated within every population. However, the high accuracy of AI may come at a cost of losing explainability (to patients and clinicians) on how the technology works.

Model for early allograft function is predictive of early graft loss in donation after circulatory death liver transplantation

Donation after circulatory death (DCD) liver transplantation is associated with higher rates of graft loss. In this paper, we explored whether the Model for Early Allograft Function (MEAF) predicted outcome in DCD liver transplantation. We performed a retrospective analysis of prospectively collected data from all adult DCD (Maastricht 3) livers transplanted in Cambridge and Edinburgh between 1 January 2011 and 30 June 2017, excluding those undergoing any form of machine perfusion. 187 DCD liver transplants were performed during the study period. DCD liver transplants with a lower MEAF score had a significantly better survival compared to those with a high MEAF score (Mantel-Cox P < .0001); this was largely due to early graft loss. Beyond 28 days post-transplant, there were no significant long-term graft or patient survival differences irrespective of the grade of MEAF (Mantel-Cox P = .64 and P = .43, respectively). The MEAF score correlated with the length of ICU (P = .0011) and hospital stay (P = .0007), but did not predict the requirement for retransplantation for ischemic cholangiopathy (P = .37) or readmission (P = .74). In this study, a high MEAF score predicted early graft loss, but not the subsequent need for re-transplantation or late graft failure as a result of intrahepatic ischemic bile duct pathology.

Post Liver Transplantation Survival and Related Prognostic Factors among Adult Recipients in Tehran Liver Transplant Center; 2002-2019

BACKGROUND

Liver transplantation is a standard treatment for patients with end-stage liver disease (ESLD). However, with increasing demand for this treatment and limited resources, it is available only to patients who are more likely to survive. The primary aim was to determine prognostic factors for survival.

METHODS

We collected data from 597 adult patients with ESLD, who received a single organ and initial orthotopic liver transplantation (OLT) in our center between 20 March 2008 and 20 March 2018. In this historical cohort study, univariate and multiple Cox model were used to determine prognostic factors of survival after transplantation.

RESULTS

After a median follow-up of 825 (0-3889) days, 111 (19%) patients died. Survival rates were 88%, 85%, 82% and 79% at 90 days, 1 year, 3 years, and 5 years, respectively. Older patients (HR = 1.27; 95% CI: 1.01-1.59), presence of pre-OLT ascites (HR = 2.03; 95% CI: 1.16-3.57), pre-OLT hospitalization (HR = 1.88; 95% CI:1.02-3.46), longer operative time (HR = 1.006; 95% CI: 1.004-1.008), post-OLT dialysis (HR = 3.51; 95% CI: 2.07-5.94), cancer (HR = 2.69; 95% CI: 1.23-5.89) and AID (HR = 2.04; 95% CI: 1.17-3.56) as underlying disease versus hepatitis, and higher pre-OLT creatinine (HR = 1.67; 95% CI: 1.10-2.52) were associated with decreased survival.

CONCLUSION

In this center, not only are survival outcomes excellent, but also younger patients, cases with better pre-operative health conditions, and those without complications after OLT have superior survival.

Novel Real-time Prediction of Liver Graft Function During Hypothermic Oxygenated Machine Perfusion Before Liver Transplantation

OBJECTIVE

The aim of this study was to determine the predictive value of machine perfusate analysis on graft outcome.

BACKGROUND

Ex situ machine perfusion (MP) is gaining increasing interest to potentially repair injured organs and to assess organ function. In the field of liver transplantation, however, no studies exist on reliable prediction of graft function during MP.

METHODS

We have used hypothermic oxygenated perfusion (HOPE) for donation after circulatory death (DCD) or extended criteria donation after brain death (DBD) human liver grafts during the last 7 years. Our series includes 100 HOPE-treated liver-transplanted patients with an overall tumor-censored 5-year graft survival of 89%. We monitored 54 livers during HOPE in terms of fluorometric analysis of released mitochondrial flavin (flavin mononucleotide, FMN) in the machine perfusate.

RESULTS

Real-time optical measurement of mitochondrial FMN release in machine perfusates of livers disclosed a strong correlation with lactate clearance and coagulation factors at day 1 and 2 after transplantation. Receiver-operating characteristic curve analysis revealed an area under the curve (AUROC) of 0.79 [95% confidence interval (CI), 0.62-0.97] for severe allograft dysfunction and for early graft loss (AUROC 0.93, 95% CI, 0.84-1.0).

CONCLUSIONS

Assessment of flavin, a marker of mitochondrial complex I injury, in the perfusate provides a fast prediction of liver graft function and loss during ex situ MP before implantation. This finding may have high clinical relevance, as liver grafts from extended DBD or DCD donors carry considerable risks for recipients. On-line estimation of outcome before implantation would therefore substantially increase safe utilization of liver grafts.

Short- and long-term mortality after liver transplantation in patients with and without hepatocellular carcinoma in the UK

Background

The increasing demand for liver transplantation has led to considerable changes in characteristics of donors and recipients. This study evaluated the short- and long-term mortality of recipients with and without hepatocellular carcinoma (HCC) in the UK between 1997 and 2016.

Methods

First-time elective adult liver transplant recipients in the UK were identified and four successive eras of transplantation were compared. Hazard ratios (HRs) comparing the impact of era on short-term (first 90 days) and longer-term (from 90 days to 5 years) mortality were estimated, with adjustment for recipient and donor characteristics.

Results

Some 1879 recipients with and 7661 without HCC were included. There was an increase in use of organs donated after circulatory death (DCD), from 0 per cent in era 1 to 35·2 per cent in era 4 for recipients with HCC, and from 0·2 to 24·1 per cent for non-HCC recipients. The 3-year mortality rate decreased from 28·3 per cent in era 1 to 16·9 per cent in era 4 (adjusted HR 0·47, 95 per cent c.i. 0·35 to 0·63) for recipients with HCC, and from 20·4 to 9·3 per cent (adjusted HR 0·44, 0·36 to 0·53) for those without HCC. Comparing era 4 with era 1, improvements were more marked in short-term than in long-term mortality, both for recipients with HCC (0–90 days: adjusted HR 0·20, 0·10 to 0·39; 90 days to 5 years: adjusted HR 0·52, 0·35 to 0·75; P = 0·043) and for non-HCC recipients (0–90 days: adjusted HR 0·32, 0·24 to 0·42; 90 days to 5 years: adjusted HR 0·52, 0·40 to 0·67; P = 0·024).

Conclusion

In the past 20 years, the mortality rate after liver transplantation has more than halved, despite increasing use of DCD donors. Improvements in overall survival can be explained by decreases in short-term and longer-term mortality.

Adult liver transplantation: UK clinical guideline - part 2: surgery and post-operation

Survival rates for patients following liver transplantation exceed 90% at 12 months and approach 70% at 10 years. Part 1 of this guideline has dealt with all aspects of liver transplantation up to the point of placement on the waiting list. Part 2 explains the organ allocation process, organ donation and organ type and how this influences the choice of recipient. After organ allocation, the transplant surgery and the critical early post-operative period are, of necessity, confined to the liver transplant unit. However, patients will eventually return to their referring secondary care centre with a requirement for ongoing supervision. Part 2 of this guideline concerns three key areas of post liver transplantation care for the non-transplant specialist: (1) overseeing immunosuppression, including interactions and adherence; (2) the transplanted organ and how to initiate investigation of organ dysfunction; and (3) careful oversight of other organ systems, including optimising renal function, cardiovascular health and the psychosocial impact. The crucial significance of this holistic approach becomes more obvious as time passes from the transplant, when patients should expect the responsibility for managing the increasing number of non-liver consequences to lie with primary and secondary care.

Encouraging Split Liver Transplantation for Two Adult Recipients to Mitigate the High Incidence of Wait-list Mortality in The Setting of Extreme Shortage of Deceased Donors

Background: Organ demand for liver transplantation (LT) is constantly increasing. Split liver transplantation (SPLT) is an ideal option for increasing the number of available liver grafts for transplantation and ameliorating organ shortage to a certain degree. However, SPLT for two adult recipients is still not broadly applied. Methods: We retrospectively analyzed the outcomes of SPLT for adult recipients at a single center. All donor, recipient, and transplantation factors were thoroughly investigated to clarify factors affecting patient outcomes after LT. Results: One hundred consecutive adult SPLTs were performed during the study period. Early mortality and 1-year mortality occurred in 21 and 31 recipients, respectively. On multivariate analysis, graft weight (p = 0.036, odds ratio = 0.99, 95% confidence interval = 0.98–0.99) was the independent risk factor associated with early mortality; however, no factor was significantly related to 1-year mortality. On receiver operating characteristic curve analysis, a graft weight of 580 g was identified the cutoff for stratifying outcomes. Recipients transplanted with a graft weighing ≥580 g had significantly better outcome as compared with other recipients (p = 0.001). Moreover, SPLT remarkably provided a better survival benefit for recipients than those on the LT wait-list (p < 0.0001). Conclusions: Given the considerable incidence of wait-list mortality, SPLT for two adult recipients should be encouraged whenever possible to increase the donor pool and benefit patients awaiting LT. Nonetheless, caution should be taken with a smaller graft weight owing to the risk of early graft loss.

Kidney Donor Profile Index Is a Reliable Alternative to Liver Donor Risk Index in Quantifying Graft Quality in Liver Transplantation

Background.

The most established metric for estimating graft survival from donor characteristics in liver transplantation is the liver donor risk index (LDRI). The LDRI is calculated from donor and transplant-related variables, including cold ischemic time. Because cold ischemic time is unknown at the time of organ offer, LDRI is not available for organ acceptance decisions. In contrast, the kidney donor profile index (KDPI) is derived purely from donor variables known at the time of offer and thus calculated for every deceased donor in the United States. The similarity in donor factors included in LDRI and KDPI led us to hypothesize that KDPI would reliably approximate LDRI in estimating graft survival in liver transplantation.

Methods.

The United Network of Organ Sharing registry was queried for adults who underwent deceased donor liver transplantation from 2002 to 2016. The cohort was divided into quintiles of KDPI and LDRI, and graft survival was calculated according to Kaplan Meier. Hazard ratios for LDRI and KDPI were estimated from Cox proportional hazards models, and Uno’s concordance statistic was compared.

Results.

In our analysis of 63 906 cases, KDPI closely approximated LDRI in estimating liver graft survival, with an equivalent concordance statistic of 0.56.

Conclusions.

We conclude that KDPI can serve as a reasonable alternative to LDRI in liver acceptance decisions.

Transient Cold Storage Prior to Normothermic Liver Perfusion May Facilitate Adoption of a Novel Technology

Clinical adoption of normothermic machine perfusion (NMP) may be facilitated by simplifying logistics and reducing costs. This can be achieved by cold storage of livers for transportation to recipient centers before commencing NMP. The purpose of this study was to assess the safety and feasibility of post-static cold storage normothermic machine perfusion (pSCS-NMP) in liver transplantation. In this multicenter prospective study, 31 livers were transplanted. The primary endpoint was 30-day graft survival. Secondary endpoints included the following: peak posttransplant aspartate aminotransferase (AST), early allograft dysfunction (EAD), postreperfusion syndrome (PRS), adverse events, critical care and hospital stay, biliary complications, and 12-month graft survival. The 30-day graft survival rate was 94%. Livers were preserved for a total of 14 hours 10 minutes ± 4 hours 46 minutes, which included 6 hours 1 minute ± 1 hour 19 minutes of static cold storage before 8 hours 24 minutes ± 4 hours 4 minutes of NMP. Median peak serum AST in the first 7 days postoperatively was 457 U/L (92-8669 U/L), and 4 (13%) patients developed EAD. PRS was observed in 3 (10%) livers. The median duration of initial critical care stay was 3 days (1-20 days), and median hospital stay was 13 days (7-31 days). There were 7 (23%) patients who developed complications of grade 3b severity or above, and 2 (6%) patients developed biliary complications: 1 bile leak and 1 anastomotic stricture with no cases of ischemic cholangiopathy. The 12-month overall graft survival rate (including death with a functioning graft) was 84%. In conclusion, this study demonstrates that pSCS-NMP was feasible and safe, which may facilitate clinical adoption.