The trials and tribulations of liver allocation

Body Size Remains the Major Source of Sex Disparity Despite Updated Liver Transplant Allocation Policies

BACKGROUND

Efforts to address US liver transplant (LT) access inequities continue, yet disparities linked to candidate traits persist.

METHODS

Analyzing national registry data pre- and post-Acuity Circle (AC) policy, our study assessed the impact of low body surface area (BSA) on LT waitlist mortality. The outcomes of LT candidates listed in the pre-AC era (n = 39 227) and post-AC (n = 38 443) were compared for patients with low BSA (22.9% pre-AC and 23.3% post-AC).

RESULTS

Fine-Gray competing risk models highlighted that candidates with low BSA had a lower likelihood of LT both pre-AC (hazard ratio [HR] 0.93; 95% confidence interval [CI], 0.92-0.95) and post-AC (HR 0.96; 95% CI, 0.94-0.98), with minimal improvement in waitlist mortality/dropout risk from pre-AC (HR 1.15; 95% CI, 1.09-1.21) to post-AC (HR 1.13; 95% CI, 1.06-1.19). Findings were mostly reaffirmed by Cox regression models incorporating the trajectory of Model for End-stage Liver Disease (MELD) scores as time-dependent covariates. Regions 3, 5, and 7 showed notable LT waitlist disparities among low BSA patients post-AC policy. Causal mediation analysis revealed that low BSA and the difference between MELD-sodium and MELD 3.0 (MELD_D, as a proxy for the potential impact of the introduction of MELD 3.0) largely explained the sex disparity in AC allocation (percent mediated 90.4).

CONCLUSIONS

LT waitlist disparities for female candidates persist, largely mediated by small body size. Although MELD 3.0 may reduce some disparities, further body size adjustments for in allocation models are justified.

Transplant benefit-based offering of deceased donor livers in the United Kingdom

BACKGROUND & AIMS

The National Liver Offering Scheme (NLOS) was introduced in the UK in 2018 to offer livers from deceased donors to patients on the national waiting list based, for most patients, on calculated transplant benefit. Before NLOS, livers were offered to transplant centres by geographic donor zones and, within centres, by estimated recipient need for a transplant.

METHODS

UK Transplant Registry data on patient registrations and transplants were analysed to build statistical models for survival on the list (M1) and survival post-transplantation (M2). A separate cohort of registrations - not seen by the models before - was analysed to simulate what liver allocation would have been under M1, M2 and a transplant benefit score (TBS) model (combining both M1 and M2), and to compare these allocations to what had been recorded in the UK Transplant Registry. The number of deaths on the waiting list and patient life years were used to compare the different simulation scenarios and to select the optimal allocation model. Registry data were monitored, pre- and post-NLOS, to understand the performance of the scheme.

RESULTS

The TBS was identified as the optimal model to offer donation after brain death (DBD) livers to adult and large paediatric elective recipients. In the first 2 years of NLOS, 68% of DBD livers were offered using the TBS to this type of recipient. Monitoring data indicate that mortality on the waiting list post-NLOS significantly decreased compared with pre-NLOS (p <0.0001), and that patient survival post-listing was significantly greater post-compared to pre-NLOS (p = 0.005).

CONCLUSIONS

In the first two years of NLOS offering, waiting list mortality fell while post-transplant survival was not negatively impacted, delivering on the scheme's objectives.

IMPACT AND IMPLICATIONS

The National Liver Offering Scheme (NLOS) was introduced in the UK in 2018 to increase transparency of the deceased donor liver offering process, maximise the overall survival of the waiting list population, and improve equity of access to liver transplantation. To our knowledge, it is the first scheme that offers organs based on statistical prediction of transplant benefit: the transplant benefit score. The results are important to the transplant community - from healthcare practitioners to patients - and demonstrate that, in the first two years of NLOS offering, waiting list mortality fell while post-transplant survival was not negatively impacted, thus delivering on the scheme's objectives. The scheme continues to be monitored to ensure that the transplant benefit score remains up-to-date and that signals that suggest the possible disadvantage of some patients are investigated.

Should AI allocate livers for transplant? Public attitudes and ethical considerations

BACKGROUND

Allocation of scarce organs for transplantation is ethically challenging. Artificial intelligence (AI) has been proposed to assist in liver allocation, however the ethics of this remains unexplored and the view of the public unknown. The aim of this paper was to assess public attitudes on whether AI should be used in liver allocation and how it should be implemented.

METHODS

We first introduce some potential ethical issues concerning AI in liver allocation, before analysing a pilot survey including online responses from 172 UK laypeople, recruited through Prolific Academic.

FINDINGS

Most participants found AI in liver allocation acceptable (69.2%) and would not be less likely to donate their organs if AI was used in allocation (72.7%). Respondents thought AI was more likely to be consistent and less biased compared to humans, although were concerned about the "dehumanisation of healthcare" and whether AI could consider important nuances in allocation decisions. Participants valued accuracy, impartiality, and consistency in a decision-maker, more than interpretability and empathy. Respondents were split on whether AI should be trained on previous decisions or programmed with specific objectives. Whether allocation decisions were made by transplant committee or AI, participants valued consideration of urgency, survival likelihood, life years gained, age, future medication compliance, quality of life, future alcohol use and past alcohol use. On the other hand, the majority thought the following factors were not relevant to prioritisation: past crime, future crime, future societal contribution, social disadvantage, and gender.

CONCLUSIONS

There are good reasons to use AI in liver allocation, and our sample of participants appeared to support its use. If confirmed, this support would give democratic legitimacy to the use of AI in this context and reduce the risk that donation rates could be affected negatively. Our findings on specific ethical concerns also identify potential expectations and reservations laypeople have regarding AI in this area, which can inform how AI in liver allocation could be best implemented.

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.

Life Expectancy after Liver Transplantation for NASH

Introduction: Non-Alcoholic Steatohepatitis is an increasing reason for liver transplantation in the western world. Knowledge of recipient life expectancy may assist in prudent allocation of a relatively scarce supply of donor livers. Research Questions: We calculated life expectancies for Non-alcoholic steatohepatitis (NASH) patients both at time of transplant and one year later, stratified by key risk factors, and examined whether survival has improved in recent years. Design: Data on 6635 NASH patients who underwent liver transplantation in the MELD era (2002-2018) from the United States OPTN database were analyzed using the Cox proportional hazards regression model and life table methods. Results: Factors related to survival were age, presence of diabetes or hepatic encephalopathy (HE), and whether the patient required dialysis in the week prior to transplant. Other important factors were whether the patient was working, hospitalization prior to transplant, ventilator support, and length of hospital stay (LOS). Survival improved over the study period at roughly 4.5% per calendar year during the first year posttransplant, though no improvement was observed in those who had survived one year. Conclusion: Life expectancy in NASH transplant patients was much reduced from normal, and varied according to age, medical factors, status at transplant, and post transplant course. Over the 17-year study period, patient survival improved markedly during the first year posttransplant, though not thereafter. The results given here may prove helpful in medical decision-making regarding treatment for both liver disease and other medical conditions, as they provide both clinicians and their patients with evidence-based information on prognosis.

From Haphazard to a Sustainable Normothermic Regional Perfusion Service: A Blueprint for the Introduction of Novel Perfusion Technologies

Normothermic Regional Perfusion (NRP) has shown encouraging clinical results. However, translation from an experimental to routine procedure poses several challenges. Herein we describe a model that led to the implementation of NRP into standard clinical practice in our centre following an iterative process of refinement incorporating training, staffing and operative techniques. Using this approach we achieved a four-fold increase in trained surgical staff and a 6-fold increase in competent senior organ preservation practitioners in 12 months, covering 93% of the retrieval calls. We now routinely provide NRP throughout the UK and attended 186 NRP retrievals from which 225 kidneys, 26 pancreases and 61 livers have been transplanted, including 5 that were initially declined by all UK transplant centres. The 61 DCD(NRP) liver transplants undertaken exhibited no primary non-function or ischaemic cholangiopathy with up to 8 years of follow-up. This approach also enabled successful implementation of ex situ normothermic liver perfusion which together with NRP contributed 37.5% of liver transplant activity in 2021. Perfusion technologies (in situ and ex situ) are now supported by a team of Advanced Perfusion and Organ Preservation Specialists. The introduction of novel perfusion technologies into routine clinical practice presents significant challenges but can be greatly facilitated by developing a specific role of Advanced Perfusion and Organ Preservation Specialist supported by a robust education, training and recruitment programme.

Life Expectancy After Liver Transplantation for Alcoholic Cirrhosis

BACKGROUND

Alcohol-associated liver disease is the leading cause of liver transplantation in the western world. For these patients we calculated life expectancies both at time of transplant and several years later, stratified by key risk factors, and determined if survival has improved in recent years.

METHODS

Data on 14 962 patients with alcohol-associated liver disease who underwent liver transplantation in the MELD era (2002-2018) from the United States Organ Procurement and Transplantation Network database were analyzed using the Cox proportional hazards regression model and life table methods.

RESULTS

Demographic and past medical history factors related to survival were patient age, presence of diabetes or severe hepatic encephalopathy, and length of hospital stay. Survival improved over the study period, at roughly 3% per calendar year during the first 5 years posttransplant and 1% per year thereafter.

CONCLUSIONS

Life expectancy in transplanted patients with alcohol-associated liver disease was much reduced from normal, and varied according to age, medical risk factors, and functional status. Survival improved modestly over the study period. Information on patient longevity can be helpful in making treatment decisions.

A meta-analysis on the prevalence of chronic kidney disease in liver transplant candidates and its associated risk factors and outcomes

Pre-liver transplant (LT) chronic kidney disease (CKD) has emerged as a leading cause of post-operative morbidity. We aimed to report the prevalence, associated risk factors, and clinical outcomes in patients with pre-LT CKD. Meta-analysis and systematic review were conducted for included cohort and cross-sectional studies. Studies comparing healthy and patients with s pre-LT CKD were included. Outcomes were assessed with pooled hazard ratios. 15 studies were included, consisting of 82,432 LT patients and 26,754 with pre-LT CKD. Pooled prevalence of pre-LT CKD was 22.35% (CI: 15.30%-32.71%). Diabetes mellitus, hypertension, viral hepatitis, and non-alcoholic fatty liver disease, and older age were associated with increased risk of pre-LT CKD: (OR 1.72 CI: 1.15-2.56, P = 0.01), (OR 2.23 CI: 1.76-2.83, P < 0.01), (OR 1.09; CI: 1.05-1.13, P < 0.01), (OR 1.73; CI: 1.10-2.71 P = 0.03), and (MD: 2.92 years; CI: 1.29-4.55years; P < 0.01) respectively. Pre-LT CKD was significantly associated with increased mortality (HR 1.38; CI: 1.2-1.59; P < 0.01), post-LT end-stage renal disease and post-LT CKD. Almost a quarter of pre-LT patients have CKD and it is significantly associated with post-operative morbidity and mortality. However, long-term outcomes remain unclear due to a lack of studies reporting such outcomes.

Atrial reconstruction, distal gastrectomy with Ante-situm liver resection and autotransplantation for hepatocellular carcinoma with atrial tumor thrombus: A case report

RATIONALE

Hepatocellular with tumor thrombi extending into 3 hepatic veins (HVs) and right atrium presents as a real clinical challenge. We report the first documented case of surgical resection of an advanced hepatocellular carcinoma (HCC) with extensive invasion to distal stomach, atrium and hepatic vasculatures.

PATIENT CONCERNS

We present a case of 48-years old man with abdominal mass accompanying shortness of breath after activities.

DIAGNOSES

Preoperative examination revealed giant HCC with tumor thrombi extending into portal vein, HVs, inferior vena cava, and atrium.

INTERVENTIONS

Distal stomach involvement was confirmed at surgery and, distal gastrectomy, atrial reconstruction and ante-situm liver resection and autotransplantation under cardio-pulmonary bypass were performed.

OUTCOMES

The operation time was 490 minutes, extracorporeal circulation time 124 minutes, and anhepatic time 40 minutes. Postoperative follow-up revealed normal hepatic and cardiac function with no sign of recurrence.

LESSONS

This case illustrates that the extensive invasion of HCC to major vasculature and adjacent organs may not necessarily preclude the liver autotransplantation with multi-visceral resection as the treatment option of extremely advanced HCC patients.