The Impact of Combined Warm Ischemia Time on Development of Acute Kidney Injury in Donation After Circulatory Death Liver Transplantation: Stay Within the Golden Hour

Post Liver Transplant Renal Dysfunction-Evaluation, Management and Immunosuppressive Practice

Liver transplantation (LT) is an effective and lifesaving treatment for patients with end-stage liver disease and hepatocellular carcinoma. Significant improvement in intermediate and long-term survival has been possible due to advancements in immunosuppressive therapy, perioperative care, and surgical techniques. Despite these advances, metabolic complications, including diabetes mellitus, cardiovascular diseases, malignancies, and renal dysfunction, are challenging issues after LT. Acute kidney injury (AKI) and chronic kidney disease (CKD) after LT are common and result in significant morbidity and mortality. Early diagnosis of kidney injury after LT is challenging, and no technique has yet proven effective in prediction of renal dysfunction. The methods for assessing renal function range from formulas that predict glomerular filtration rate to non-invasive biomarkers. The universal adoption of the model for end-stage liver disease has a direct impact on the incidence of peri-transplant AKI and development of CKD in the long-term. Post-LT renal dysfunction is multifactorial and is usually a result of pre-transplantation comorbidities, occurrence of renal dysfunction on the waiting list, perioperative events, and post-transplant nephrotoxic immunosuppressive medication use. Early identification of patients at risk for renal dysfunction and adoption of preventive measures are crucial in the pre-transplant period. No data are currently available to suggest a surgical technique that reliably demonstrates renal protection. Nephroprotective strategies during LT follow accepted surgical practice guidelines, such as maintenance of intravascular volume and mean arterial pressure. The management of kidney disease following LT is challenging, as by the time the serum creatinine is significantly elevated, few interventions impact the course of progression. Early nephroprotective measures are strongly advised and they mostly center on delaying the administration of calcineurin inhibitors (CNIs) during the initial postoperative period, lowering CNI dosage and combining CNI with mycophenolate mofetil and everolimus. The reasons for renal failure following LT, the techniques used to diagnose it, and the therapies designed to preserve renal function both immediately and late after LT are all critically evaluated in this review.

Complications in Post-Liver Transplant Patients

Liver transplantation (LT) is the treatment of choice for liver failure and selected cases of malignancies. Transplantation activity has increased over the years, and indications for LT have been widened, leading to organ shortage. To face this condition, a high selection of recipients with prioritizing systems and an enlargement of the donor pool were necessary. Several authors published their case series reporting the results obtained with the use of marginal donors, which seem to have progressively improved over the years. The introduction of in situ and ex situ machine perfusion, although still strongly debated, and better knowledge and treatment of the complications may have a role in achieving better results. With longer survival rates, a significant number of patients will suffer from long-term complications. An extensive review of the literature concerning short- and long-term outcomes is reported trying to highlight the most recent findings. The heterogeneity of the behaviors within the different centers is evident, leading to a difficult comparison of the results and making explicit the need to obtain more consent from experts.

Development of a nomogram for the prediction of acute kidney injury after liver transplantation: a model based on clinical parameters and postoperative cystatin C level

BACKGROUND

Acute kidney injury (AKI) is common after liver transplantation (LT). We developed a nomogram model to predict post-LT AKI.

METHODS

A total of 120 patients were eligible for inclusion in the study. Clinical information was extracted from the institutional electronic medical record system. Blood samples were collected prior to surgery and immediately after surgery. Univariable and multivariate logistic regression were used to identify independent risk factors. Finally, a nomogram was developed based on the final multivariable logistic regression model.

RESULTS

In total, 58 (48.3%) patients developed AKI. Multivariable logistic regression revealed four independent risk factors for post-LT AKI: operation duration [odds ratio (OR) = 1.728, 95% confidence interval (CI) = 1.121-2.663, p = 0.013], intraoperative hypotension (OR = 3.235, 95% CI = 1.316-7.952, p = 0.011), postoperative cystatin C level (OR = 1.002, 95% CI = 1.001-1.004, p = 0.005) and shock (OR = 4.002, 95% CI = 0.893-17.945, p = 0.070). Receiver operating characteristic curve analysis was used to evaluate model discrimination. The area under the curve value was 0.815 (95% CI = 0.737-0.894).

CONCLUSION

The model based on combinations of clinical parameters and postoperative cystatin C levels had a higher predictive performance for post-LT AKI than the model based on clinical parameters or postoperative cystatin C level alone. Additionally, we developed an easy-to-use nomogram based on the final model, which could aid in the early detection of AKI and improve the prognosis of patients after LT.

Early allograft dysfunction after living donor liver transplantation-current concepts and future directions

Early allograft dysfunction (EAD) after liver transplantation is a significant clinical problem that negatively impacts graft and patient outcomes. The rising incidence of EAD and what it means concerning living donor liver transplantation (LDLT) is an area of great interest. However, EAD after LDLT is a complex research topic yet to be reviewed comprehensively. Most of the literature on EAD is based on experience in deceased donor liver transplantation, and limited information is available in the context of LDLT. Thus, in this review, we present an overview of EAD after LDLT and have attempted to present balanced points of view on all its aspects, such as definitions, pathogenesis, risk factors, predictive markers, and management. The review aims to broadly overview the nature and extent of ongoing research evidence on this complex topic and inform practice in the field by identifying key concepts and knowledge gaps and highlighting areas that require further inquiry.

Simultaneous thoracic and abdominal donation after circulatory death organ recovery: the abdominal surgeon's perspective

PURPOSE OF THE REVIEW

To summarize the international experience with heart-liver (joint) donation after circulatory death (DCD) procurements and to explore the technical challenges in joint abdominal and thoracic DCD procurement.

RECENT FINDINGS

Following completion of the Donors After Circulatory Death Heart Trial in the US, combined thoracic and abdominal DCD is poised to become the standard of care, expanding access to life-saving heart and lung allografts. DCD heart procurement relies on collection of donor blood for priming of the normothermic perfusion pump, which delays cooling of abdominal organs and increases risk of ischemic injury. We review the effect of donor ischemia time on abdominal organs, with several proposed technical solutions to optimize transplant outcomes for all organs.

SUMMARY

The strategies reviewed in this manuscript may inform clinical decision-making, preoperative coordination between thoracic and abdominal procurement teams, and surgical technique for joint DCD procurements. Several approaches to organ procurement organization (OPO) and national policy, as well as future areas of focus for research are proposed.

Alternative forms of portal vein revascularization in liver transplant recipients with complex portal vein thrombosis

BACKGROUND & AIMS

Complex portal vein thrombosis (PVT) is a challenge in liver transplantation (LT). Extra-anatomical approaches to portal revascularization, including renoportal (RPA), left gastric vein (LGA), pericholedochal vein (PCA), and cavoportal (CPA) anastomoses, have been described in case reports and series. The RP4LT Collaborative was created to record cases of alternative portal revascularization performed for complex PVT.

METHODS

An international, observational web registry was launched in 2020. Cases of complex PVT undergoing first LT performed with RPA, LGA, PCA, or CPA were recorded and updated through 12/2021.

RESULTS

A total of 140 cases were available for analysis: 74 RPA, 18 LGA, 20 PCA, and 28 CPA. Transplants were primarily performed with whole livers (98%) in recipients with median (IQR) age 58 (49-63) years, model for end-stage liver disease score 17 (14-24), and cold ischemia 431 (360-505) minutes. Post-operatively, 49% of recipients developed acute kidney injury, 16% diuretic-responsive ascites, 9% refractory ascites (29% with CPA, p <0.001), and 10% variceal hemorrhage (25% with CPA, p = 0.002). After a median follow-up of 22 (4-67) months, patient and graft 1-/3-/5-year survival rates were 71/67/61% and 69/63/57%, respectively. On multivariate Cox proportional hazards analysis, the only factor significantly and independently associated with all-cause graft loss was non-physiological portal vein reconstruction in which all graft portal inflow arose from recipient systemic circulation (hazard ratio 6.639, 95% CI 2.159-20.422, p = 0.001).

CONCLUSIONS

Alternative forms of portal vein anastomosis achieving physiological portal inflow (i.e., at least some recipient splanchnic blood flow reaching transplant graft) offer acceptable post-transplant results in LT candidates with complex PVT. On the contrary, non-physiological portal vein anastomoses fail to resolve portal hypertension and should not be performed.

IMPACT AND IMPLICATIONS

Complex portal vein thrombosis (PVT) is a challenge in liver transplantation. Results of this international, multicenter analysis may be used to guide clinical decisions in transplant candidates with complex PVT. Extra-anatomical portal vein anastomoses that allow for at least some recipient splanchnic blood flow to the transplant allograft offer acceptable results. On the other hand, anastomoses that deliver only systemic blood flow to the allograft fail to resolve portal hypertension and should not be performed.

Donor eligibility criteria and liver graft acceptance criteria during normothermic regional perfusion: A systematic review

Acceptance of liver grafts from donations after circulatory death (DCD) largely remains a "black box," particularly due to the unpredictability of the agonal phase. Abdominal normothermic regional perfusion (aNRP) can reverse ischemic injury early during the procurement procedure, and it simultaneously enables graft viability testing to unravel this black box. This review evaluates current protocols for liver viability assessment to decide upon acceptance or decline during aNRP. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was used, and relevant literature databases were searched. The primary outcome consisted of criteria for liver graft viability assessment. Secondary outcomes included survival, primary nonfunction (PNF), early dysfunction, and biliary complications. A total of 14 articles were included in the analysis. In all protocols, a combination of criteria was used to assess suitability of the liver for transplantation. As many as 12 studies (86%) used macroscopic assessment, 12 studies (86%) used alanine transaminase (ALT) levels in perfusate, 9 studies (64%) used microscopic assessment, and 7 studies (50%) used lactate levels as assessment criteria. The organ utilization rate (OUR) was 16% for uncontrolled donation after circulatory death (uDCD) and 64% for controlled donation after circulatory death (cDCD). The most used acceptation criterion in uDCD is ALT level (31%), while in cDCD macroscopic aspect (48%) is most used. Regarding postoperative complications, PNF occurred in 13% (6%-25%) of uDCD livers and 3% (2%-4%) of cDCD livers. In uDCD, the 1-year graft and patient survival rates were 75% (66%-82%) and 82% (75%-88%). In cDCD, the 1-year graft and patient survival rates were 91% (89%-93%) and 93% (91%-94%), respectively. In conclusion, the currently used assessment criteria consist of macroscopic aspect and transaminase levels. The acceptance criteria should be tailored according to donor type to prevent an unacceptable PNF rate in uDCD and to increase the relatively modest OUR in cDCD.

Mitochondria and Cancer Recurrence after Liver Transplantation—What Is the Benefit of Machine Perfusion?

Tumor recurrence after liver transplantation has been linked to multiple factors, including the recipient’s tumor burden, donor factors, and ischemia-reperfusion injury (IRI). The increasing number of livers accepted from extended criteria donors has forced the transplant community to push the development of dynamic perfusion strategies. The reason behind this progress is the urgent need to reduce the clinical consequences of IRI. Two concepts appear most beneficial and include either the avoidance of ischemia, e.g., the replacement of cold storage by machine perfusion, or secondly, an endischemic organ improvement through perfusion in the recipient center prior to implantation. While several concepts, including normothermic perfusion, were found to reduce recipient transaminase levels and early allograft dysfunction, hypothermic oxygenated perfusion also reduced IRI-associated post-transplant complications and costs. With the impact on mitochondrial injury and subsequent less IRI-inflammation, this endischemic perfusion was also found to reduce the recurrence of hepatocellular carcinoma after liver transplantation. Firstly, this article highlights the contributing factors to tumor recurrence, including the surgical and medical tissue trauma and underlying mechanisms of IRI-associated inflammation. Secondly, it focuses on the role of mitochondria and associated interventions to reduce cancer recurrence. Finally, the role of machine perfusion technology as a delivery tool and as an individual treatment is discussed together with the currently available clinical studies.

Liver perfusion strategies: what is best and do ischemia times still matter?

PURPOSE OF REVIEW

This review describes recent developments in the field of liver perfusion techniques.

RECENT FINDINGS

Dynamic preservation techniques are increasingly tested due to the urgent need to improve the overall poor donor utilization. With their exposure to warm ischemia, livers from donors after circulatory death (DCD) transmit additional risk for severe complications after transplantation. Although the superiority of dynamic approaches compared to static-cold-storage is widely accepted, the number of good quality studies remains limited. Most risk factors, particularly donor warm ischemia, and accepted thresholds are inconsistently reported, leading to difficulties to assess the impact of new preservation technologies. Normothermic regional perfusion (NRP) leads to good outcomes after DCD liver transplantation, with however short ischemia times. While randomized controlled trials (RCT) with NRP are lacking, results from the first RCTs with ex-situ perfusion were reported. Hypothermic oxygenated perfusion was shown to protect DCD liver recipients from ischemic cholangiopathy. In contrast, endischemic normothermic perfusion seems to not impact on the development of biliary complications, although this evidence is only available from retrospective studies.

SUMMARY

Dynamic perfusion strategies impact posttransplant outcomes and are increasingly commissioned in various countries along with more evidence from RCTs. Transparent reporting of risk and utilization with uniform definitions is required to compare the role of different preservation strategies in DCD livers with prolonged ischemia times.

Normothermic Regional Perfusion and Hypothermic Oxygenated Machine Perfusion for Livers Donated After Controlled Circulatory Death With Prolonged Warm Ischemia Time: A Matched Comparison With Livers From Brain-Dead Donors

Prolonged warm ischemia time (WIT) has a negative prognostic value in liver transplantation (LT) using grafts procured after circulatory death (DCD). To assess the value of abdominal normothermic regional perfusion (A-NRP) associated with dual hypothermic oxygenated machine perfusion (D-HOPE) in controlled DCD LT, prospectively collected data on LTs performed between January 2016 and July 2021 were analyzed. Outcome of controlled DCD LTs performed using A-NRP + D-HOPE (n = 20) were compared to those performed with grafts procured after brain death (DBD) (n = 40), selected using propensity-score matching. DCD utilization rate was 59.5%. In the DCD group, median functional WIT, A-NRP and D-HOPE time was 43, 246, and 205 min, respectively. Early outcomes of DCD grafts recipients were comparable to those of matched DBD LTs. In DCD and DBD group, incidence of anastomotic biliary complications and ischemic cholangiopathy was 15% versus 22% (p = 0.73) and 5% versus 2% (p = 1), respectively. One-year patient and graft survival was 100% versus 95% (p = 0.18) and 90% versus 95% (p = 0.82). In conclusion, the association of A-NRP + D-HOPE in DCD LT with prolonged WIT allows achieving comparable outcomes to DBD LT.

Primary Nonfunction of the Liver Allograft

Severe allograft dysfunction, as opposed to the expected immediate function, following liver transplantation is a major complication, and the clinical manifestations of such that lead to either immediate retransplant or death are the catastrophic end of the spectrum. Primary nonfunction (PNF) has declined in incidence over the years, yet the impact on patient and healthcare teams, and the burden on the organ pool in case of the need for retransplant should not be underestimated. There is no universal test to define the diagnosis of PNF, and current criteria are based on various biochemical parameters surrogate of liver function; moreover, a disparity remains within different healthcare systems on selecting candidates eligible for urgent retransplantation. The impact on PNF from traditionally accepted risk factors has changed somewhat, mainly driven by the rising demand for organs, combined with the concerted approach by clinicians on the in-depth understanding of PNF, optimal graft recipient selection, mitigation of the clinical environment in which a marginal graft is reperfused, and postoperative management. Regardless of the mode, available data suggest machine perfusion strategies help reduce the incidence further but do not completely avert the risk of PNF. The mainstay of management relies on identifying severe allograft dysfunction at a very early stage and aggressive management, while excluding other identifiable causes that mimic severe organ dysfunction. This approach may help salvage some grafts by preventing total graft failure and also maintaining a patient in an optimal physiological state if retransplantation is considered the ultimate patient salvage strategy.

Novel Composite Endpoint for Assessing Outcomes in Liver Transplantation: Arterial and Biliary Complication-Free Survival

Transplant and patient survival are the validated endpoints to assess the success of liver transplantation (LT). This study evaluates arterial and biliary complication-free survival (ABCFS) as a new metric. ABC, considered as an event, was an arterial or biliary complication of Dindo-Clavien grade ≥III complication dated at the interventional, endoscopic, or surgical treatment required to correct it. ABCFS was defined as the time from the date of LT to the dates of first ABC, death, relisting, or last follow-up (transplant survival is time from LT to repeat LT or death). Following primary whole LT (n = 532), 106 ABCs occurred and 99 (93%) occurred during the first year after LT. An ABC occurring during the first year after LT (overall rate 19%) was an independent factor associated with transplant survival (hazard ratio [HR], 3.17; P < 0.001) and patient survival (HR, 2.7; P = 0.002) in univariate and multivariate analyses. This result was confirmed after extension of the cohort to split-liver graft, donation after circulatory death, or re-LT (n = 658). Data from 2 external cohorts of primary whole LTs (n = 249 and 229, respectively) confirmed that the first-year ABC was an independent prognostic factor for transplant survival but not for patient survival. ABCFS was correlated with transplant and patient survival (ρ = 0.85 [95% CI, 0.78-0.90] and 0.81 [95% CI, 0.71-0.88], respectively). Preoperative factors known to influence 5-year transplant survival influenced ABCFS after 1 year of follow-up. The 1-year ABCFS was indicative of 5-year transplant survival. ABCFS is a reproducible metric to evaluate the results of LT after 1 year of follow-up and could serve as a new endpoint in clinical trials.

Development and validation of a nomogram for predicting acute kidney injury after orthotopic liver transplantation

BACKGROUND

We aim to develop and validate a nomogram model for predicting severe acute kidney injury (AKI) after orthotopic liver transplantation (OLT).

METHODS

A total of 576 patients who received OLT in our center were enrolled. They were assigned to the development and validation cohort according to the time of inclusion. Univariable and multivariable logistic regression using the forward variable selection routine were applied to find risk factors for post-OLT severe AKI. Based on the results of multivariable analysis, a nomogram was developed and validated. Patients were followed up to assess the long-term mortality and development of chronic kidney disease (CKD).

RESULTS

Overall, 35.9% of patients were diagnosed with severe AKI. Multivariable logistic regression analysis revealed that recipients' BMI (OR 1.10, 95% CI 1.04-1.17, p = 0.012), hypertension (OR 2.32, 95% CI 1.22-4.45, p = 0.010), preoperative serum creatine (sCr) (OR 0.96, 95% CI 0.95-0.97, p < 0.001), and intraoperative fresh frozen plasm (FFP) transfusion (OR for each 1000 ml increase 1.34, 95% CI 1.03-1.75, p = 0.031) were independent risk factors for post-OLT severe AKI. They were all incorporated into the nomogram. The area under the ROC curve (AUC) was 0.73 (p < 0.05) and 0.81 (p < 0.05) in the development and validation cohort. The calibration curve demonstrated the predicted probabilities of severe AKI agreed with the observed probabilities (p > 0.05). Kaplan-Meier survival analysis showed that patients in the high-risk group stratified by the nomogram suffered significantly poorer long-term survival than the low-risk group (HR 1.92, p < 0.01). The cumulative risk of CKD was higher in the severe AKI group than no severe AKI group after competitive risk analysis (HR 1.48, p < 0.05).

CONCLUSIONS

With excellent predictive abilities, the nomogram may be a simple and reliable tool to identify patients at high risk for severe AKI and poor long-term prognosis after OLT.

How to Preserve Liver Grafts From Circulatory Death With Long Warm Ischemia? A Retrospective Italian Cohort Study With Normothermic Regional Perfusion and Hypothermic Oxygenated Perfusion

BACKGROUND

Donation after circulatory death (DCD) in Italy, given its 20-min stand-off period, provides a unique bench test for normothermic regional perfusion (NRP) and dual hypothermic oxygenated machine perfusion (D-HOPE).

METHODS

We coordinated a multicenter retrospective Italian cohort study with 44 controlled DCD donors, who underwent NRP, to present transplant characteristics and results. To rank our results according to the high donor risk, we matched and compared a subgroup of 37 controlled DCD livers, preserved with NRP and D-HOPE, with static-preserved controlled DCD transplants from an established European program.

RESULTS

In the Italian cohort, D-HOPE was used in 84% of cases, and the primary nonfunction rate was 5%. Compared with the matched comparator group, the NRP + D-HOPE group showed a lower incidence of moderate and severe acute kidney injury (stage 2: 8% versus 27% and stage 3: 3% versus 27%; P = 0.001). Ischemic cholangiopathy remained low (2-y proportion free: 97% versus 92%; P = 0.317), despite the high-risk profile resulting from the longer donor warm ischemia in Italy (40 versus 18 min; P < 0.001).

CONCLUSIONS

These data suggest that NRP and D-HOPE yield good results in DCD livers with prolonged warm ischemia.

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.

Evaluation of Liver Graft Donation After Euthanasia

Importance

The option of donating organs after euthanasia is not well known. Assessment of the results of organ transplants with grafts donated after euthanasia is essential to justify the use of this type of organ donation.

Objectives

To assess the outcomes of liver transplants (LTs) with grafts donated after euthanasia (donation after circulatory death type V [DCD-V]), and to compare them with the results of the more commonly performed LTs with grafts from donors with a circulatory arrest after the withdrawal of life-supporting treatment (type III [DCD-III]).

Design, Setting, and Participants

This retrospective multicenter cohort study analyzed medical records and LT data for most transplant centers in the Netherlands and Belgium. All LTs with DCD-V grafts performed from the start of the donation after euthanasia program (September 2012 for the Netherlands, and January 2005 for Belgium) through July 1, 2018, were included in the analysis. A comparative cohort of patients who received DCD-III grafts was also analyzed. All patients in both cohorts were followed up for at least 1 year. Data analysis was performed from September 2019 to December 2019.

Exposures

Liver transplant with either a DCD-V graft or DCD-III graft.

Main Outcomes and Measures

Primary outcomes were recipient and graft survival rates at years 1, 3, and 5 after the LT. Secondary outcomes included postoperative complications (early allograft dysfunction, hepatic artery thrombosis, and nonanastomotic biliary strictures) within the first year after the LT.

Results

Among the cohort of 47 LTs with DCD-V grafts, 25 organ donors (53%) were women and the median (interquartile range [IQR]) age was 51 (44-59) years. Among the cohort of 542 LTs with DCD-III grafts, 335 organ donors (62%) were men and the median (IQR) age was 49 (37-57) years. Median (IQR) follow-up was 3.8 (2.1-6.3) years. In the DCD-V cohort, 30 recipients (64%) were men, and the median (IQR) age was 56 (48-64) years. Recipient survival in the DCD-V cohort was 87% at 1 year, 73% at 3 years, and 66% at 5 years after LT. Graft survival among recipients was 74% at 1 year, 61% at 3 years, and 57% at 5 years after LT. These survival rates did not differ statistically significantly from those in the DCD-III cohort. Incidence of postoperative complications did not differ between the groups. For example, the occurrence of early allograft dysfunction after the LT was found to be 13 (31%) in the DCD-V cohort and 219 (45%) in the DCD-III cohort. The occurrence of nonanastomotic biliary strictures after the LT was found to be 7 (15%) in the DCD-V cohort and 83 (15%) in the DCD-III cohort.

Conclusions and Relevance

The findings of this cohort study suggest that LTs with DCD-V grafts yield similar outcomes as LTs with DCD-III grafts; therefore, grafts donated after euthanasia may be a justifiable option for increasing the organ donor pool. However, grafts from these donations should be considered high-risk grafts that require an optimal donor selection process and logistics.

Sequential Organ Failure Assessment (SOFA) Score-Based Factors Predict Early Mortality in High-Risk Patients with Living Donor Liver Transplant

Background

Patients with a Sequential Organ Failure Assessment (SOFA) score >7 on post-transplant day (POD) 7 have been reported to have a higher risk of short-term mortality after living donor liver transplant (LDLT). We sought to identify factors that were associated with early mortality in this high-risk population.

Material/Methods

A total of 102 patients with a high SOFA score (>7) on POD 7 were enrolled, of which 72 (70.6%) were assigned to the survivor group, and the other 30 (29.4%) patients were assigned to the non-survivor group according to post-transplant 3-month results. Demographics, clinical data, operative parameters, and individual SOFA component scores were collected. Independent risk factors for 3-month mortality were identified by multivariate logistic regression analysis using backward elimination procedures.

Results

Of 102 high SOFA score patients, the 3-month mortality rate after LDLT in our study was 29.4%. Four independent risk factors were indicative for early death: graft-to-recipient weight ratio (GRWR) <0.8 (hazard ratio [HR]=3.00; 95% CI=1.05–8.09; P=0.041), longer warm ischemia time (HR=37.84; 95% CI=1.63–880.77; P=0.024), high liver component of the SOFA score, and cardiovascular component of the SOFA score (liver component: HR=10.39; 95% CI=1.77–60.89; P=0.009 and cardiovascular component: HR=13.34; 95% CI=2.22–80.12; P=0.005).

Conclusions

In conclusion, 3-month mortality among patients with high SOFA score on POD 7 is associated with multiple independent risk factors, including smaller GRWR, longer warm ischemia time, and higher category of liver and cardiovascular component of SOFA score. By recognizing high-risk patients earlier, the LDLT outcomes may be improved by timely intensive therapies.

Chronic Kidney Disease as a Systemic Inflammatory Syndrome: Update on Mechanisms Involved and Potential Treatment

Chronic kidney disease (CKD) is characterized by manifestations and symptoms involving systemic organs and apparatus, associated with elevated cardiovascular morbidity and mortality, bone disease, and other tissue involvement. Arterial hypertension (AH), diabetes mellitus (DM), and dyslipidemia, with glomerular or congenital diseases, are the traditional risk factors recognized as the main causes of progressive kidney dysfunction evolving into uremia. Acute kidney injury (AKI) has recently been considered an additional risk factor for the worsening of CKD or the development of CKD de novo. Evidence underlies the role of systemic inflammation as a linking factor between AKI and CKD, recognizing the role of inflammation in AKI evolution to CKD. Moreover, abnormal increases in oxidative stress (OS) and inflammatory status in CKD seem to exert an important pathogenetic role, with significant involvement in the clinical management of this condition. With our revision, we want to focus on and update the inflammatory mechanisms responsible for the pathologic conditions associated with CKD, with particular attention on the development of AKI and AKI-CKD de novo, the alteration of calcium-phosphorus metabolism with bone disease and CKD-MBD syndrome, the status of malnutrition and malnutrition-inflammation complex syndrome (MICS) and protein-energy wasting (PEW), uremic sarcopenia, the status of OS, and the different inflammatory pathways, highlighting a new approach to CKD. The depth comprehension of the mechanisms underlying the development of inflammation in CKD may present new possible therapeutic approaches in CKD and hopefully improve the management of correlated morbidities and provide a reduction in associated mortality.

Donation after circulatory death liver transplantation: An in-depth analysis and propensity score-matched comparison

BACKGROUND

Careful donor-recipient matching and reduced ischemia times have improved outcomes following donation after circulatory death (DCD) liver transplantation (LT). This study examines a single-center experience with DCD LT including high-acuity and hospitalized recipients.

METHODS

DCD LT outcomes were compared to a propensity score-matched (PSM) donation after brain death (DBD) LT cohort (1:4); 32 DCD LT patients and 128 PSM DBD LT patients transplanted from 2008 to 2018 were included. Analyses included Kaplan-Meier estimates and Cox proportional hazards models examining patient and graft survival.

RESULTS

Median MELD score in the DCD LT cohort was 22, with median MELD of 27 for DCD LT recipients with decompensated cirrhosis. No difference in mortality or graft loss was found (p < .05) between DCD LT and PSM DBD LT at 3 years post-transplant, nor was DCD an independent risk factor for patient or graft survival. Post-LT severe acute kidney injury was similar in both groups. Ischemic-type biliary lesions (ITBL) occurred in 6.3% (n = 2) of DCD LT recipients, resulting in 1 graft loss and 1 death.

CONCLUSION

This study supports that DCD LT outcomes can be similar to DBD LT, with a low rate of ITBL, in a cohort including high-acuity recipients. Strict donor selection criteria, ischemia time minimization, and avoiding futile donor/recipient combinations are essential considerations.

Different Severity of Clinical Outcomes Between the 2 Subgroups of Stage 1 Acute Kidney Injury After Liver Transplantation

BACKGROUND

Although the Kidney Disease: Improving Global Outcomes (KDIGO) criteria is used to define acute kidney injury (AKI) after liver transplantation, the criteria was criticized for including 2 heterogeneous groups of different serum creatinine (sCr) criteria together in AKI stage 1. We investigated whether there are significant differences in clinical outcomes between 2 subgroups of patients within AKI stage 1.

METHODS

A total of 1440 cases were reviewed. The AKI stage 1 (n = 443) were divided into 2 subgroups based on changes in sCr level (stage 1a: ≥0.3 mg/dL of absolute sCr increase, n = 251; stage 1b: ≥50% relative sCr increase, n = 192). Propensity score analysis was performed between stage 1a and 1b groups, yielding 157 matched pairs. We compared the length of hospital stay, early allograft dysfunction, and 5-year all-cause mortality between these subgroups after matching. Kaplan-Meier analyses were performed to compare the graft or overall survival between the subgroups after matching. Sensitivity analysis for Acute Kidney Injury Network (AKIN) criteria was performed.

RESULTS

Length of hospital stay and 5-year all-cause mortality was significantly worse in patients with stage 1b compared to stage 1a after matching. Five-year graft or patient survival was significantly worse in patients with stage 1b compared to stage 1a after matching (Log-rank test P = 0.022 and P = 0.027, respectively). These results were the same regarding AKIN criteria.

CONCLUSIONS

The KDIGO criteria for AKI stage 1 could be further divided into 2 substages with different severity of clinical outcomes. This modified criteria could give additional prognostic information in patients undergoing liver transplantation.

Hypothermic Oxygenated Perfusion Versus Normothermic Regional Perfusion in Liver Transplantation From Controlled Donation After Circulatory Death: First International Comparative Study

OBJECTIVE

To compare HOPE and NRP in liver transplantation from cDCD.

SUMMARY OF BACKGROUND DATA

Liver transplantation after cDCD is associated with higher rates of graft loss. Dynamic preservation strategies such as NRP and HOPE may offer safer use of cDCD grafts.

METHODS

Retrospective comparative cohort study assessing outcomes after cDCD liver transplantation in 1 Swiss (HOPE) and 6 French (NRP) centers. The primary endpoint was 1-year tumor-death censored graft and patient survival.

RESULTS

A total of 132 and 93 liver grafts were transplanted after NRP and HOPE, respectively. NRP grafts were procured from younger donors (50 vs 61 years, P < 0.001), with shorter functional donor warm ischemia (22 vs 31 minutes, P < 0.001) and a lower overall predicted risk for graft loss (UK-DCD-risk score 6 vs 9 points, P < 0.001). One-year tumor-death censored graft and patient survival was 93% versus 86% (P = 0.125) and 95% versus 93% (P = 0.482) after NRP and HOPE, respectively. No differences in non-anastomotic biliary strictures, primary nonfunction and hepatic artery thrombosis were observed in the total cohort and in 32 vs. 32 propensity score-matched recipients CONCLUSION:: NRP and HOPE in cDCD achieved similar post-transplant recipient and graft survival rates exceeding 85% and comparable to the benchmark values observed in standard DBD liver transplantation. Grafts in the HOPE cohort were procured from older donors and had longer warm ischemia times, and consequently achieved higher utilization rates. Therefore, randomized controlled trials with intention-to-treat analysis are needed to further compare both preservation strategies, especially for high-risk donor-recipient combinations.

Expedited placement to maximize utilization of marginal organs

PURPOSE OF REVIEW

Deceased donation represents the largest supply of organs for transplant in the United States. Organs with suboptimal characteristics related to donor disease or recovery-related issues are increasingly discarded at the time of recovery, prompting late allocation to candidates later in the match sequence. Late allocation contributes to organ injury by prolonging cold ischemia, which may further lead to the risk of organ discard, despite the potential to provide benefit to certain transplant candidates.

RECENT FINDINGS

Expedited placement of marginal organs has emerged as a strategy to address the growing problem of organ discard of marginal organs that have been declined late after recovery. In this review, we describe the basis for expedited organ placement, and approaches to facilitating placement of these grafts, drawing examples from kidney and liver donation and transplantation globally.

SUMMARY

There is significant global variation in practice related to late allocation. Multiple policy mechanisms exist to facilitate expedited placement, including simultaneous offers to multiple centers, predesignation of aggressive centers, and increasing organ procurement organization autonomy in late allocation. Optimizing late allocation of deceased donor organs holds significant promise to increase the number of transplants.

Favorable Outcomes of Liver Transplantation from Controlled Circulatory Death Donors Using Normothermic Regional Perfusion Compared to Brain Death Donors

BACKGROUND

Liver transplantation (LT) from controlled donation after circulatory death (cDCD) was initiated in France in 2015 under a protocol based on the use of normothermic regional perfusion (NRP) before organ procurement. The aim was to compare outcomes following cDCD LT with NRP and donation after brain death (DBD) LT.

METHODS

This is a multicenter retrospective study comparing cDCD LT with NRP and DBD LT. A case-matched study (1:2) was performed using the variables such as recipient and donor age, indication of LT.

RESULTS

A total of 50 patients from the cDCD group were matched to 100 patients from the DBD group. From postoperative days 1-4, serum transaminase release was significantly lower in the cDCD group compared to the DBD group (P < 0.05). Early allograft dysfunction (cDCD: 18% versus DBD: 32%; P = 0.11), acute kidney injury (26% versus 33%; P = 0.49), 90-d graft loss (2% versus 5%; P = 0.66), and arterial (4% versus 12%; P = 0.19) and biliary (16% versus 17%; P = 0.94) complications were similar between the 2 groups. The 2-y graft survival was 88% for cDCD group and 85% for DBD group (P = 0.91). The 2-y patient survival was 90% for cDCD group and 88% for DBD group (P = 0.68).

CONCLUSIONS

This study provides evidence that cDCD LT following postmortem NRP can be safely and effectively performed in selected recipients with similar graft and patient survival outcomes, without increased rates of biliary complications and early graft dysfunction compared to DBD LT.

Donor hepatectomy time influences ischemia-reperfusion injury of the biliary tree in donation after circulatory death liver transplantation

BACKGROUND

Donor hepatectomy time is associated with graft survival after liver transplantation. The aim of this study was to identify the impact of donor hepatectomy time on biliary injury during donation after circulatory death liver transplantation.

METHODS

First, bile duct biopsies of livers included in (pre)clinical machine perfusion research were analyzed. Secondly, of the same livers, bile samples were collected during normothermic machine perfusion. Lastly, a nationwide retrospective cohort study was performed including 273 adult patients undergoing donation after circulatory death liver transplantation between January 1, 2002 and January 1, 2017. Primary endpoint was development of non-anastomotic biliary strictures within 2 years of donation after circulatory death liver transplantation. Cox proportional-hazards regression analyses were used to assess the influence of hepatectomy time on the development of non-anastomotic biliary strictures.

RESULTS

Livers with severe histological bile duct injury had a higher median hepatectomy time (P = .03). During normothermic machine perfusion, livers with a hepatectomy time >50 minutes had lower biliary bicarbonate and bile pH levels. In the nationwide retrospective study, donor hepatectomy time was an independent risk factor for non-anastomotic biliary strictures after donation after circulatory death liver transplantation (Hazard Ratio 1.18 per 10 minutes increase, 95% Confidence Interval 1.06-1.30, P value = .002).

CONCLUSION

Donor hepatectomy time negatively influences histological bile duct injury before normothermic machine perfusion and bile composition during normothermic machine perfusion. Additionally, hepatectomy time is a significant independent risk factor for the development of non-anastomotic biliary strictures after donation after circulatory death liver transplantation.

Intraoperative Oxygen Delivery and Acute Kidney Injury after Liver Transplantation

Although intraoperative hemodynamic variables were reported to be associated with acute kidney injury (AKI) after liver transplantation, the time-dependent association between intraoperative oxygen delivery and AKI has not yet been evaluated. We reviewed 676 cases of liver transplantation. Oxygen delivery index (DO2I) was calculated at least ten times during surgery. AKI was defined according to the Kidney Disease Improving Global Outcomes criteria. The area under the curve (AUC) was calculated as below a DO2I of 300 (AUC < 300), 400 and 500 mL/min/m2 threshold. Also, the cumulative time below a DO2I of 300 (Time < 300), 400, and 500 mL/min/m2 were calculated. Multivariable logistic regression analysis was performed to evaluate whether AUC < 300 or time < 300 was independently associated with the risk of AKI. As a sensitivity analysis, propensity score matching analysis was performed between the two intraoperative mean DO2I groups using a cutoff of 500 ml/min/m2, and the incidence of AKI was compared between the groups. Multivariable analysis showed that AUC < 300 or time < 300 was an independent predictor of AKI (AUC < 300: odds ratio [OR] = 1.10, 95% confidence interval [CI] 1.06-1.13, time < 300: OR = 1.10, 95% CI 1.08-1.14). Propensity score matching yielded 192 pairs of low and high mean DO2I groups. The incidence of overall and stage 2 or 3 AKI was significantly higher in the lower DO2I group compared to the higher group (overall AKI: lower group, n = 64 (33.3%) vs. higher group, n = 106 (55.2%), P < 0.001). In conclusion, there was a significant time-dependent association between the intraoperative poor oxygen delivery <300 mL/min/m2 and the risk of AKI after liver transplantation. The intraoperative optimization of oxygen delivery may mitigate the risk of AKI.

The AKI Prediction Score: a new prediction model for acute kidney injury after liver transplantation

BACKGROUND

Acute kidney injury (AKI) is a frequent complication after liver transplantation. Although numerous risk factors for AKI have been identified, their cumulative impact remains unclear. Our aim was therefore to design a new model to predict post-transplant AKI.

METHODS

Risk analysis was performed in patients undergoing liver transplantation in two centres (n = 1230). A model to predict severe AKI was calculated, based on weight of donor and recipient risk factors in a multivariable regression analysis according to the Framingham risk-scheme.

RESULTS

Overall, 34% developed severe AKI, including 18% requiring postoperative renal replacement therapy (RRT). Five factors were identified as strongest predictors: donor and recipient BMI, DCD grafts, FFP requirements, and recipient warm ischemia time, leading to a range of 0-25 score points with an AUC of 0.70. Three risk classes were identified: low, intermediate and high-risk. Severe AKI was less frequently observed if recipients with an intermediate or high-risk were treated with a renal-sparing immunosuppression regimen (29 vs. 45%; p = 0.007).

CONCLUSION

The AKI Prediction Score is a new instrument to identify recipients at risk for severe post-transplant AKI. This score is readily available at end of the transplant procedure, as a tool to timely decide on the use of kidney-sparing immunosuppression and early RRT.

Intraoperative Hepatic Blood Inflow Can Predict Early Acute Kidney Injury following DCD Liver Transplantation: A Retrospective Observational Study

Purpose

Acute kidney injury (AKI) is a major and severe complication following donation-after-circulatory-death (DCD) liver transplantation (LT) and is associated with increased postoperative morbidity and mortality. However, the risk factors and the prognosis factors of AKI still need to be further explored, and the relativity of intraoperative hepatic blood inflow (HBI) and AKI following LT has not been discussed yet. The purpose of this study was to investigate the correlation between HBI and AKI and to construct a prediction model of early acute kidney injury (EAKI) following DCD LT with the combination of HBI and other clinical parameters.

Methods

Clinical data of 132 patients who underwent DCD liver transplantation at the first hospital of China Medical University from April 2005 to March 2017 were analyzed. Data of 105 patients (the first ten years of patients) were used to develop the prediction model. Then we assessed the clinical usefulness of the prediction models in the validation cohort (27 patients). EAKI according to Kidney Disease Improving Global Outcomes (KDIGO) criteria based on serum creatinine increase during 7-day of postoperative follow-up.

Results

After Least Absolute Shrinkage and Selection Operator (LASSO) regression and simplification, a simplified prediction model consisting of the Child-Turcotte-Pugh (CTP) score (p=0.033), anhepatic phase (p=0.014), packed red blood cell (pRBC) transfusion (p=0.027), and the HBI indexed by height (HBI/h) (p=0.002) was established. The C-indexes of the model in the development and validation cohort were 0.823 [95% CI, 0.738-0.908] and 0.921 [95% CI, 0.816-1.000], respectively.

Conclusions

In this study, we demonstrated the utility of HBI/h as a predictor for EAKI following DCD LT, as well as the clinical usefulness of the prediction model through the combination of the CTP score, anhepatic phase, pRBC transfusion and HBI/h.

Expanding the Donor Pool With the Use of Extended Criteria Donation After Circulatory Death Livers

Use of donation after circulatory death (DCD) donor livers for transplantation has remained cautious in the United States. The aim of this study was to demonstrate the expansion of a DCD liver transplantation (LT) program with the use of extended criteria donor (ECD) DCD livers. After institutional review board approval, 135 consecutive DCD LTs were retrospectively studied. ECD DCD livers were defined as those with 1 of the following factors: donor age >50 years, donor body mass index >35 kg/m² , donor functional warm ischemia time >30 minutes, and donor liver macrosteatosis >30%. An optimization protocol was introduced in July 2011 to improve outcomes of DCD LT, which included thrombolytic donor flush and efforts to minimize ischemia times. The impact of this protocol on outcomes was evaluated in terms of graft loss, ischemic cholangiopathy (IC), and change in DCD LT volume. Of 135 consecutive DCD LTs, 62 were ECD DCDs. In total, 24 ECD DCD LTs were performed before (era 1) and 38 after the institution of optimization protocol (era 2), accounting for an increase in the use of ECD DCD livers from 39% to 52%. Overall outcomes of ECD DCD LT improved in era 2, with a significantly lower incidence of IC (5% versus 17% in era 1; P = 0.03) and better 1-year graft survival (93% versus 75% in era 1; P = 0.07). Survival outcomes for ECD DCD LT in era 2 were comparable to matched deceased donor LT. With the expansion of the DCD donor pool, the number of DCD LTs performed at our center gradually increased in era 2 to account for >20% of the center's LT volume. In conclusion, with the optimization of perioperative conditions, ECD DCD livers can be successfully transplanted to expand the donor pool for LT.

Influence of the procurement surgeon on transplanted abdominal organ outcomes: An SRTR analysis to evaluate regional organ procurement collaboration

Single-center studies have demonstrated regional organ procurement collaboration to reduce travel redundancy and improve procurement efficiency. We studied deceased donor kidney, liver, and pancreas transplants performed in the United States between 2002 and 2014 using the Scientific Registry of Transplant Recipients (SRTR). We compared graft failure (GF), death-censored graft failure (DCGF), and patient death (PD) between organs procured by surgeons from the recipient's center (transplant procurement team [TPT]) versus surgeons from a different center (NTPT). Primary nonfunction (PNF) was assessed for liver and kidney and delayed graft function (DGF) for kidney using mixed-effects logistic modeling. There were 64 906 liver (61.6% TPT), 118 152 kidney (26.1% TPT), 10 832 simultaneous pancreas kidney (SPK; 56.6% TPT), and 4378 solitary pancreas (SP; 34.0% TPT) transplants. When compared to NTPT, DCGF for organs procured by TPT was significantly less for liver (adjusted HR: 0.93; 95% CI: 0.88-0.98) and marginally significant for kidney (0.97; 0.93-1.00) and SPK (0.90; 0.82-1.00), and not significant for SP (0.98; 0.86 -1.11). DGF for TPT kidney was significantly lower (adjusted OR 0.91; 0.87-0.95). Albeit modest, our findings demonstrate a difference between locally procured organs and those procured by the implanting team. Elucidating the etiology of these differences will enhance regional organ procurement collaboration.

Chronic Kidney Disease After Liver Transplantation: Impact of Extended Criteria Grafts

The use of extended criteria donor (ECD) grafts has been associated with acute kidney injury (AKI) after liver transplantation. However, the relation between graft quality and development of chronic kidney disease (CKD) remains unknown. Therefore, the aim of this study was to analyze the impact of ECD grafts for CKD after liver transplantation. All patients (2007-2015) transplanted for end-stage liver disease at our center were assessed. Longterm kidney function was divided into 4 groups: no CKD (estimated glomerular filtration rate [eGFR], ≥60 mL/minute/1.73 m² ), mild CKD (eGFR, 30-59 mL/minute/1.73 m² ), severe CKD (eGFR, 15-29 mL/minute/1.73 m² ), and end-stage renal disease (ESRD). Marginal donation after brain death (DBD) grafts (donor age, >70 years; body mass index, >35 kg/m² ; cold storage, >12 hours) and donation after circulatory death (DCD) grafts were considered ECD grafts. Overall, 926 patients were included, and 43% received an ECD graft (15% marginal DBD; 28% DCD). After 5 years, 35% developed CKD; severe CKD and ESRD occurred in only 2% and 1%, respectively. CKD rates were comparable for all 3 graft groups (standard group, 36%; marginal DBD group, 29%; DCD group, 35%; standard versus marginal DBD groups, P = 0.16; standard versus DCD group, P = 0.80). None of the ECD criteria were identified as independent risk factors in a Cox regression model for CKD. Risk factors included recipient age, female sex, and preoperative kidney function. Furthermore, recipients who had severe acute kidney injury (AKI; Kidney Disease: Improving Global Outcomes stages 2 and 3) had a 1.8-fold increased risk for CKD. Longterm kidney function of recipients with severe AKI depended on the recovery of kidney function in the first postoperative week. In conclusion, there is no direct relation between the use of ECD grafts and CKD after liver transplantation. However, caution should be taken in recipients who experience severe AKI, regardless of graft type.

Revascularization Time in Liver Transplantation: Independent Prediction of Inferior Short- and Long-term Outcomes by Prolonged Graft Implantation

BACKGROUND

Strategies for successful transplantation are much needed in the era of organ shortage, and there has been a resurgence of interest on the impact of revascularization time (RT) on outcomes in liver transplantation (LT).

METHODS

All primary LT performed in Birmingham between 2009 and 2014 (n = 678) with portal reperfusion first were stratified according to RT (<44 minutes vs ≥44 minutes) and graft quality (standard liver graft [SLG], Donor Risk Index < 2.3 vs marginal liver graft [MLG], Donor Risk Index ≥ 2.3).

RESULTS

Revascularization time of 44 minutes or longer resulted in significantly greater incidence of early allograft dysfunction (EAD) (29% vs 47%, P < 0.001), posttransplant acute kidney injury (AKI) (39% vs 60%, P < 0.001), and new-onset AKI (37% vs 56%, P < 0.001), along with poor long-term outcome (3-year graft survival 92% vs 83%, P = 0.001; 3-year patient survival 87% vs 79%, P = 0.004). On multivariable analysis, RT ≥ 44 was a significant independent predictor of EAD, renal dysfunction, and overall graft survival, but not patient survival. The cumulative effect of prolonged revascularization in marginal grafts (MLG) resulted in the worst transplant outcome compared with all other groups, which could be mitigated by rapid revascularization (SLG, SLG, MLG vs MLG; EAD 24%, 39%, 39% vs 69%; AKI 32%, 46%, 51% vs 70%; 3-year graft survival 94%, 87%, 88% vs 70%, respectively; each P < 0.001). Factors associated with lack of abdominal space, larger grafts, and surgical skills were predictive of RT ≥ 44.

CONCLUSIONS

Shorter graft revascularization is a protective factor in LT, particularly in the setting of graft marginality. Careful graft-recipient matching and emphasis on surgical expertise may aid in achieving better outcomes in LT.

Early Persistent Progressive Acute Kidney Injury and Graft Failure Post Liver Transplantation

Background

Acute kidney injury (AKI) in the setting of liver transplantation is a common and multifaceted complication. Studies in the general population have demonstrated worse prognosis with AKI episodes that persist for a longer duration. Our primary objective was to evaluate the impact of early AKI episodes that are persistent or progressive in nature, on patient outcomes and graft survival.

Methods

This was a retrospective cohort study including all patients who received a liver transplant between 2011 and 2015 at our center. Moderate to severe AKI episodes (AKIN II or III) were recorded immediately before transplantation and after surgery until hospital discharge. We evaluated the incidence density rate (IDR) of graft failure and the time to graft failure in patients with persistent or progressive AKI (ppAKI) as compared to controls.

Results

Two hundred seventy-nine patients received 301 deceased donor liver allografts. Progressive or persistent AKI was documented in more than half of transplant cases (152/301). The rate of graft loss was 3 times higher in the ppAKI group (25%) versus the controls (8.7%). The IDR of graft failure was 13.79 per 100 case-years in the ppAKI group as compared with 3.79 per 100 case-years in the controls (IDR ratio, 3.64; 95 % confidence interval, 1.88–7.50). After adjusting for hepatic artery thrombosis, ischemic cholangiopathy, infectious complications and Model for End-stage Liver Disease, ppAKI was associated with a decreased graft survival time.

Conclusions

Persistent or progressive AKI after liver transplantation is associated with an increased incidence rate of graft failure and is an independent predictor of decreased graft survival time.

Prediction of Acute Kidney Injury after Liver Transplantation: Machine Learning Approaches vs. Logistic Regression Model

Acute kidney injury (AKI) after liver transplantation has been reported to be associated with increased mortality. Recently, machine learning approaches were reported to have better predictive ability than the classic statistical analysis. We compared the performance of machine learning approaches with that of logistic regression analysis to predict AKI after liver transplantation. We reviewed 1211 patients and preoperative and intraoperative anesthesia and surgery-related variables were obtained. The primary outcome was postoperative AKI defined by acute kidney injury network criteria. The following machine learning techniques were used: decision tree, random forest, gradient boosting machine, support vector machine, naïve Bayes, multilayer perceptron, and deep belief networks. These techniques were compared with logistic regression analysis regarding the area under the receiver-operating characteristic curve (AUROC). AKI developed in 365 patients (30.1%). The performance in terms of AUROC was best in gradient boosting machine among all analyses to predict AKI of all stages (0.90, 95% confidence interval [CI] 0.86–0.93) or stage 2 or 3 AKI. The AUROC of logistic regression analysis was 0.61 (95% CI 0.56–0.66). Decision tree and random forest techniques showed moderate performance (AUROC 0.86 and 0.85, respectively). The AUROC of support the vector machine, naïve Bayes, neural network, and deep belief network was smaller than that of the other models. In our comparison of seven machine learning approaches with logistic regression analysis, the gradient boosting machine showed the best performance with the highest AUROC. An internet-based risk estimator was developed based on our model of gradient boosting. However, prospective studies are required to validate our results.