Development and Validation of a Model to Predict Long-Term Survival After Liver Transplantation

Should patients with acute-on-chronic liver failure grade 3 receive higher priority for liver transplantation?

In this debate, the authors consider whether patients with acute-on-chronic liver failure grade 3 (ACLF-3) should receive higher liver transplant priority, with reference to the following clinical case: a 62-year-old male with a history of decompensated alcohol-associated cirrhosis, with recurrent ascites and hepatic encephalopathy, and metabolic comorbidities (type 2 diabetes mellitus, arterial hypertension and a BMI of 31 kg/m²). A few days following evaluation for liver transplantation (LT), the patient was admitted to the intensive care unit and placed on mechanical ventilation for neurological failure, FiO₂ of 0.3 with a SpO₂ of 98%, and started on norepinephrine at 0.62 μg/kg/min. He had been abstinent since the diagnosis of cirrhosis a year prior. Laboratory results at admission were: leukocyte count 12.1 G/L, international normalised ratio 2.1, creatinine 2.4 mg/dl, sodium 133 mmol/L, total bilirubin 7 mg/dl, lactate 5.5 mmol/L, with a MELD-Na score of 31 and a CLIF-C ACLF score of 67. On the 7^th day after admission, the patient was placed on the LT waiting list. On the same day, he had massive variceal bleed with hypovolemic shock requiring terlipressin, transfusion of three red blood cell units, and endoscopic band ligation. On day 10, the patient was stabilised with a low dose of norepinephrine 0.03 μg/kg/min, with no new sepsis or bleeding. However, the patient was still intubated for grade 2 hepatic encephalopathy and on renal replacement therapy with a lactate level of 3.1 mmol/L. The patient is currently categorised as having ACLF-3, with five organ failures (liver, kidney, coagulation, circulation, and respiration). Based on the severity of his liver disease and multiorgan failure, the patient is at an exceedingly high risk of death without LT. Is it appropriate to perform LT in such a patient?

Assessment of donor quality and risk of graft failure after liver transplantation: The ID2 EAL score

Accurate assessment of donor quality at the time of organ offer for liver transplantation candidates may be inadequately captured by the donor risk index (DRI). We sought to develop and validate a novel objective and simple model to assess donor risk using donor level variables available at the time of organ offer. We utilized national data from candidates undergoing primary LT (2013-2019) and assessed the prediction of graft failure 1 year after LT. The final components were donor Insulin-dependent diabetes mellitus, Donor type (DCD or DBD), cause of Death = CVA, serum creatinine, Age, height, and weight (length). The ID² EAL score had better discrimination than DRI using bootstrap corrected concordant index over time, especially in the current era. We explored donor-recipient matching. Relative risk of graft failure ranged from 1.15 to 3.5 based on relevant donor-recipient matching by the ID² EAL score. As an example, for certain recipients, a young DCD donor offer was preferable to an older DBD with relevant comorbidities. The ID² EAL score may serve as an important tool for patient discussion about donor risk and decisions regarding offer acceptance. In addition, the score may be preferable to succinctly capture donor risk in future organ allocation that considers continuous distribution (www.iddealscore.com).

Accurate long-term prediction of death for patients with cirrhosis

BACKGROUND AND AIMS

Cirrhosis is a major cause of death and is associated with extensive health care use. Patients with cirrhosis have complex treatment choices due to risks of morbidity and mortality. To optimally counsel and treat patients with cirrhosis requires tools to predict their longer-term liver-related survival. We sought to develop and validate a risk score to predict longer-term survival of patients with cirrhosis.

APPROACH AND RESULTS

We conducted a retrospective cohort study of adults with cirrhosis with no major life-limiting comorbidities. Adults with cirrhosis within the Veterans Health Administration were used for model training and internal validation, and external validation used the OneFlorida Clinical Research Consortium. We used four model-building approaches including variables predictive of cirrhosis-related mortality, focused on discrimination at key time points (1, 3, 5, and 10 years). Among 30,263 patients with cirrhosis ≤75 years old without major life-limiting comorbidities and complete laboratory data during the baseline period, the boosted survival tree models had the highest discrimination, with 1-year, 3-year, 5-year, and 10-year survival rates of 0.77, 0.81, 0.84, and 0.88, respectively. The 1-year, 3-year, and 5-year discrimination was nearly identical in external validation. Secondary analyses with imputation of missing data and subgroups by etiology of liver disease had similar results to the primary model.

CONCLUSIONS

We developed and validated (internally and externally) a risk score to predict longer-term survival of patients with cirrhosis. This score would transform management of patients with cirrhosis in terms of referral to specialty care and treatment decision-making for non-liver-related care.

"Beyond MELD" - Emerging strategies and technologies for improving mortality prediction, organ allocation and outcomes in liver transplantation

In this review article, we discuss the model for end-stage liver disease (MELD) score and its dual purpose in general and transplant hepatology. As the landscape of liver disease and transplantation has evolved considerably since the advent of the MELD score, we summarise emerging concepts, methodologies, and technologies that may improve mortality prognostication in the future. Finally, we explore how these novel concepts and technologies may be incorporated into clinical practice.

Impact of Race-Adjusted Glomerular Filtration Rate Estimation on Eligibility for Simultaneous Liver-Kidney Transplantation

Estimated glomerular filtration rate (eGFR) is adjusted for Black race in commonly used formulas. This has potential implications for access to simultaneous liver-kidney transplantation (SLKT) as qualifying criteria rely on eGFR. We performed a retrospective study of United Network for Organ Sharing national transplant registry data between February 28, 2002, and March 31, 2019, to evaluate the proportion of Black patients who would be reclassified as meeting SLKT criteria (as defined per current policies) if race adjustment were removed from 2 prominent eGFR equations (Modification of Diet in Renal Disease-4 [MDRD-4] and Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI]). Of the 7937 Black patients listed for transplant during the study period, we found that 3.6% would have been reclassified as qualifying for chronic kidney disease (CKD)-related SLKT with removal of race adjustment for MDRD-4, and 3.0% would have been reclassified with CKD-EPI; this represented 23.7% and 18.7% increases in SLKT candidacy, respectively. Reclassification impacted women more than men (eg, 4.5% versus 3.0% by MDRD-4; P < 0.05). In an exploratory analysis, patients meeting SLKT criteria by race-unadjusted eGFR equations were significantly more likely to receive liver transplantation alone (LTA) compared with SLKT. Approximately 2.0% of reclassified patients required kidney transplantation within 1 year of LTA versus 0.3% of nonreclassified patients. In conclusion, race adjustment in eGFR equations may impact SLKT candidacy for 3.0% to 4.0% of Black patients listed for LTA overall. Approximately 2.0% of patients reclassified as meeting SLKT criteria require short-term post-LTA kidney transplantation. These data argue for developing novel algorithms for glomerular filtration rate estimation free of race to promote equity.

Building a Utility-based Liver Allocation Model in Preparation for Continuous Distribution

Background.

The current model for end-stage liver disease-based liver allocation system in the United States prioritizes sickest patients first at the expense of long-term graft survival. In a continuous distribution model, a measure of posttransplant survival will also be included. We aimed to use mathematical optimization to match donors and recipients based on quality to examine the potential impact of an allocation system designed to maximize long-term graft survival.

Methods.

Cox proportional hazard models using organ procurement and transplantation network data from 2008 to 2012 were used to place donors and waitlist candidates into 5 groups of increasing risk for graft loss (1—lowest to 5—highest). A mixed integer programming optimization model was then used to generate allocation rules that maximized graft survival at 5 and 8 y.

Results.

Allocation based on mathematical optimization improved 5-y survival by 7.5% (78.2% versus 70.7% in historic cohort) avoiding 2271 graft losses, and 8-y survival by 9% (71.8% versus 62.8%) avoiding 2725 graft losses. Long-term graft survival for recipients within a quality group is highly dependent on donor quality. All candidates in groups 1 and 2 and 43% of group 3 were transplanted, whereas none of the candidates in groups 4 and 5 were transplanted.

Conclusions.

Long-term graft survival can be improved using a model that allocates livers based on both donor and recipient quality, and the interaction between donor and recipient quality is an important predictor of graft survival. Considerations for incorporation into a continuous distribution model are discussed.