International comparison of liver transplant programmes: differences in indications, donor and recipient selection and outcome between Italy and UK

The role of an integrated referral program for patients with liver disease: A network between hub and spoke centers

INTRODUCTION

Access to Liver transplantation (LT) can be affected by several barriers, resulting in delayed referral and increased risk of mortality due to complications of the underlying liver disease.

AIM

To assess the clinical characteristics and outcomes of patients with acute or chronic liver disease referred using an integrated referral program.

MATERIALS AND METHODS

An integrated referral program was developed in 1 October 2017 based on email addresses and a 24/7 telephone availability. All consecutive adult patients with liver disease referred for the first time using this referral program were prospectively collected until 1 October 2021. Characteristics and outcomes of inpatients were compared with a historical cohort of patients referred without using the integrated referral program (1 October 2015-1 October 2017). Patients were further divided according to pre- and post-Covid-19 pandemic.

RESULTS

Two hundred eighty-one referred patients were considered. End stage liver disease was the most common underlying condition (79.3%), 50.5% of patients were referred as inpatients and 74.7% were referred for LT evaluation. When inpatient referrals (n = 142) were compared with the historical cohort (n = 86), a significant increase in acute liver injury due to drugs/herbals and supplements was seen (p = 0.01) as well as an increase in End stage liver disease due to alcohol-related liver disease and NASH, although not statistically significant. A significant increase in referrals for evaluation for Trans-jugular intrahepatic portosystemic shunt placement was seen over time (5.6% vs. 1%; p = 0.01) as well as for LT evaluation (84.5% vs. 81%; p = 0.01). Transplant-free survival was similar between the study and control groups (p = 0.3). The Covid-19 pandemic did not affect trends of referrals and patient survival.

CONCLUSIONS

The development of an integrated referral program for patients with liver disease can represent the first step to standardize already existing referral networks between hub and spoke centers. Future studies should focus on the timing of referral according to different etiologies to optimize treatment options and outcomes.

Viability assessment of livers donated after circulatory determination of death during normothermic regional perfusion

BACKGROUND

Abdominal normothermic regional perfusion (A-NRP) allows in-situ reperfusion and recovery of abdominal organs metabolism in donors after circulatory death (DCD). Besides improving liver transplantation outcomes, liver injury and function can be assessed during A-NRP.

METHODS

To refine liver viability assessment during A-NRP, prospectively collected data of controlled DCD donors managed at our Institution between October 2019 and May 2022 were retrospectively analyzed. Baseline characteristics, procedural variables and A-NRP parameters of donors whose liver was successfully transplanted were compared to those of donors whose liver was discarded.

RESULTS

Twenty-seven donors were included and in 20 (74%) the liver was accepted (positive outcome). No differences between study groups were observed concerning baseline characteristics and warm ischemia times (WIT). Initial lactate levels were positively correlated with functional WIT (r2  = 0.4, p = 0.04), whereas transaminase levels were not. Blood flow during A-NRP was comparable, whereas oxygen consumption (VO2 ) was significantly higher in the positive outcome group after 1 h. Time courses of lactate, AST and ALT were significantly different between study groups (p < 0.001). Donors whose liver was accepted showed faster lactate clearance, a difference which was amplified by normalizing lactate clearance to oxygen delivery (DO2 ) and VO2 . Lactate clearance was correlated to transaminase levels and DO2 -normalized lactate clearance was the parameter best discriminating between study groups.

CONCLUSIONS

DO2 -normalized lactate clearance may represent an element of liver viability assessment during A-NRP.

Outcomes after liver transplantation using deceased after circulatory death donors: A comparison of outcomes in the UK and the US

BACKGROUND AND AIMS

Identifying international differences in utilization and outcomes of liver transplantation (LT) after donation after circulatory death (DCD) donation provides a unique opportunity for benchmarking and population-level insight.

METHODS

Adult (≥18 years) LT data between 2008 and 2018 from the UK and US were used to assess mortality and graft failure after DCD LT. We used time-dependent Cox-regression methods to estimate hazard ratios (HR) for risk-adjusted short-term (0-90 days) and longer-term (90 days-5 years) outcomes.

RESULTS

One-thousand five-hundred-and-sixty LT receipts from the UK and 3426 from the US were included. Over the study period, the use of DCD livers increased from 15.7% to 23.9% in the UK compared to 5.1% to 7.6% in the US. In the UK, DCD donors were older (UK:51 vs. US:33 years) with longer cold ischaemia time (UK: 437 vs. US: 333 min). Recipients in the US had higher Model for End-stage Liver Disease (MELD) scores, higher body mass index, higher proportions of ascites, encephalopathy, diabetes and previous abdominal surgeries. No difference in the risk-adjusted short-term mortality or graft failure was observed between the countries. In the longer-term (90 days-5 years), the UK had lower mortality and graft failure (adj.mortality HR:UK: 0.63 (95% CI: 0.49-0.80); graft failure HR: UK: 0.72, 95% CI: 0.58-0.91). The cumulative incidence of retransplantation was higher in the UK (5 years: UK: 11.9% vs. 4.6%; p < .001).

CONCLUSIONS

For those receiving a DCD LT, longer-term post-transplant outcomes in the UK are superior to the US, however, significant differences in recipient illness, graft quality and access to retransplantation were seen between the two countries.

Survival After Liver Transplantation: An International Comparison Between the United States and the United Kingdom in the Years 2008-2016

BACKGROUND

Compared with the United States, risk-adjusted mortality in the United Kingdom has historically been worse in the first 90 d following liver transplantation (LT) and better thereafter. In the last decade, there has been considerable change in the practice of LT internationally, but no contemporary large-scale international comparison of posttransplant outcomes has been conducted. This study aimed to determine disease-specific short- and long-term mortality of LT recipients in the United States and the United Kingdom.

METHODS

This retrospective international multicenter cohort study analyzed adult (≥18 y) first-time LT recipients between January 2, 2008, and December 31, 2016, using the Organ Procurement and Transplantation Network/United Network for Organ Sharing and the UK Transplant Registry databases. Time-dependent Cox regression estimated hazard ratios (HRs) comparing disease-specific risk-adjusted mortality in the first 90 d post-LT, between 90 d and 1 y, and between 1 and 5 y.

RESULTS

Forty-two thousand eight hundred seventy-four US and 4950 UK LT recipients were included. The main LT indications in the United States and the United Kingdom were hepatocellular carcinoma (25.4% and 24.9%, respectively) and alcohol-related liver disease (20.3% and 27.1%, respectively). There were no differences in mortality during the first 90 d post-LT (reference: United States; HR, 0.96; 95% confidence interval [CI], 0.82-1.12). However, between 90 d and 1 y (HR, 0.71; 95% CI, 0.59-0.85) and 1 and 5 y (HR, 0.71; 95% CI, 0.63-0.81]) the United Kingdom had lower mortality. The mortality differences between 1 and 5 y were most marked in hepatocellular carcinoma (HR, 0.71; 95% CI, 0.58-0.88) and alcohol-related liver disease patients (HR, 0.64; 95% CI, 0.45-0.89).

CONCLUSIONS

Risk-adjusted mortality in the United States and the United Kingdom was similar in the first 90 d post-LT but better in the United Kingdom thereafter. International comparisons of LT may highlight differences in healthcare delivery and help benchmarking by identifying modifiable factors that can facilitate improved global outcomes in LT.

Machine learning in liver transplantation: a tool for some unsolved questions?

Machine learning has recently been proposed as a useful tool in many fields of Medicine, with the aim of increasing diagnostic and prognostic accuracy. Models based on machine learning have been introduced in the setting of solid organ transplantation too, where prognosis depends on a complex, multidimensional and nonlinear relationship between variables pertaining to the donor, the recipient and the surgical procedure. In the setting of liver transplantation, machine learning models have been developed to predict pretransplant survival in patients with cirrhosis, to assess the best donor-to-recipient match during allocation processes, and to foresee postoperative complications and outcomes. This is a narrative review on the role of machine learning in the field of liver transplantation, highlighting strengths and pitfalls, and future perspectives.

Allocation of liver grafts worldwide - Is there a best system?

BACKGROUND & AIMS

An optimal allocation system for scarce resources should simultaneously ensure maximal utility, but also equity. The most frequent principles for allocation policies in liver transplantation are therefore criteria that rely on pre-transplant survival (sickest first policy), post-transplant survival (utility), or on their combination (benefit). However, large differences exist between centers and countries for ethical and legislative reasons. The aim of this study was to report the current worldwide practice of liver graft allocation and discuss respective advantages and disadvantages.

METHODS

Countries around the world that perform 95 or more deceased donor liver transplantations per year were analyzed for donation and allocation policies, as well as recipient characteristics.

RESULTS

Most countries use the model for end-stage liver disease (MELD) score, or variations of it, for organ allocation, while some countries opt for center-based allocation systems based on their specific requirements, and some countries combine both a MELD and center-based approach. Both the MELD and center-specific allocation systems have inherent limitations. For example, most countries or allocation systems address the limitations of the MELD system by adding extra points to recipient's laboratory scores based on clinical information. It is also clear from this study that cancer, as an indication for liver transplantation, requires special attention.

CONCLUSION

The sickest first policy is the most reasonable basis for the allocation of liver grafts. While MELD is currently the standard for this model, many adjustments were implemented in most countries. A future globally applicable strategy should combine donor and recipient factors, predicting probability of death on the waiting list, post-transplant survival and morbidity, and perhaps costs.

LAY SUMMARY

An optimal allocation system for scarce resources should simultaneously ensure maximal utility, but also equity. While the model for end-stage liver disease is currently the standard for this model, many adjustments were implemented in most countries. A future globally applicable strategy should combine donor and recipient factors predicting probability of death on the waiting list, post-transplant survival and morbidity, and perhaps costs.

Hypothermic Oxygenated Machine Perfusion of Liver Grafts from Brain-Dead Donors

Hypothermic oxygenated machine perfusion (HOPE) was introduced in liver transplantation (LT) to mitigate ischemia-reperfusion injury. Available clinical data mainly concern LT with donors after circulatory-determined death, whereas data on brain-dead donors (DBD) are scarce. To assess the impact of end-ischemic HOPE in DBD LT, data on primary adult LTs performed between March 2016 and June 2018 were analyzed. HOPE was used in selected cases of donor age >80 years, apparent severe graft steatosis, or ischemia time ≥10 hours. Outcomes of HOPE-treated cases were compared with those after static cold storage. Propensity score matching (1:2) and Bayesian model averaging were used to overcome selection bias. During the study period, 25 (8.5%) out of 294 grafts were treated with HOPE. After matching, HOPE was associated with a lower severe post-reperfusion syndrome (PRS) rate (4% versus 20%, p = 0.13) and stage 2–3 acute kidney injury (AKI) (16% versus 42%, p = 0.046). Furthermore, Bayesian model averaging showed lower transaminases peak and a lower early allograft dysfunction (EAD) rate after HOPE. A steeper decline in arterial graft resistance throughout perfusion was associated with lower EAD rate. HOPE determines a significant reduction of ischemia reperfusion injury in DBD LT.

Quality Metrics in Solid Organ Transplantation: A Systematic Review

BACKGROUND

The best approach for determining whether a transplant program is delivering high-quality care is unknown. This review aims to identify and characterize quality metrics in solid organ transplantation.

METHODS

Medline, Embase, and Cochrane Central Register of Controlled Trials were searched from inception until February 1, 2017. Relevant full text reports and conference abstracts that examined quality metrics in organ transplantation were included. Two reviewers independently extracted study characteristics and quality metrics from 52 full text reports and 24 abstracts. PROSPERO registration: CRD42016035353.

RESULTS

Three hundred seventeen quality metrics were identified and condensed into 114 unique indicators with sufficient detail to be measured in practice; however, many lacked details on development and selection, were poorly defined, or had inconsistent definitions. The process for selecting quality indicators was described in only 5 publications and patient involvement was noted in only 1. Twenty-four reports used the indicators in clinical care, including 12 quality improvement studies. Only 14 quality metrics were assessed against patient and graft survivals.

CONCLUSIONS

More than 300 quality metrics have been reported in transplantation but many lacked details on development and selection, were poorly defined, or had inconsistent definitions. Measures have focused on safety and effectiveness with very few addressing other quality domains, such as equity and patient-centeredness. Future research will need to focus on transparent and objective metric development with proper testing, evaluation, and implementation in practice. Patients will need to be involved to ensure that transplantation quality metrics measure what is important to them.