Benchmarking clinical risk prediction algorithms with ensemble machine learning for the non-invasive diagnosis of liver fibrosis in NAFLD.

Ensemble machine learning methods, like the superlearner, combine multiple models into a single one to enhance predictive accuracy. Here we explore the potential of the superlearner as a benchmarking tool for clinical risk prediction, illustrating the approach in identifying significant liver fibrosis among patients with non-alcoholic fatty liver disease (NAFLD). We used 23 demographic/clinical variables to train superlearner(s) on data from the NASH-CRN observational study (n=648) and validated models with data from the FLINT trial (n=270) and NHANES participants with NAFLD (n=1244). Comparing the superlearner's performance to existing models (FIB-4, NFS, Forns, APRI, BARD, and SAFE), it exhibited strong discriminative ability in the FLINT and NHANES validation sets, with AUCs of 0.79 (95% CI: 0.73-0.84) and 0.74 (95% CI: 0.68-0.79) respectively. Notably, the SAFE score performed similarly to the superlearner, both of which outperformed FIB-4, APRI, Forns, and BARD scores in the validation datasets. Surprisingly, the superlearner derived from 12 base models matched the performance of one with 90 base models. Overall, the superlearner, being the "best-in-class" ML predictor, excelled in detecting fibrotic NASH, and this approach can be used to benchmark the performance of conventional clinical risk prediction models.

OPTN/SRTR 2022 Annual Data Report: Liver.

In 2022, liver transplant activity continued to increase in the United States, with an all-time high of 9,527 transplants performed, representing a 52% increase over the past decade (2012-2022). Of these transplants, 8,924 (93.7%) were from deceased donors and 603 (6.3%) were from living donors. Liver transplant recipients were 94.5% adult and 5.5% pediatric. The overall size of the liver transplant waiting list contracted, with more patients being removed than added, although 10,548 adult patients still remained on the waiting list at the end of 2022. Alcohol-associated liver disease continued to be the leading diagnosis among both candidates and recipients, followed by metabolic dysfunction-associated steatohepatitis. Simultaneous liver-kidney transplant was the most common multiorgan combination, with 800 liver-kidney transplants performed in 2022; in addition, there were 303 new listings for kidney transplant via the safety net mechanism. Among adults added to the liver waiting list in 2021, 39.9% received a deceased donor liver transplant within 3 months; 45.7%, within 6 months; and 54.5%, within 1 year. Pretransplant mortality decreased to 12.3 deaths per 100 patient-years in 2022, although still 15.6% of removals from the waiting list were for death or being too sick for transplant. Graft and patient survival outcomes after deceased donor liver transplant improved, approximating pre-COVID-19 pandemic levels, with 5.1% mortality observed at 6 months; 6.8%, at 1 year; 12.7%, at 3 years; 19.8%, at 5 years; and 35.7%, at 10 years. Five-year graft and patient survival rates after living donor liver transplant exceeded those of deceased donor liver transplant. Candidates receiving model for end-stage liver disease exception points for hepatocellular carcinoma constituted 15.5% of transplants performed in 2022, with similar transplant rates and posttransplant outcomes compared to cases without hepatocellular carcinoma exception. In 2022, more pediatric liver transplant candidates were added to the waiting list and underwent transplant compared with either of the preceding 2 years, with an uptick in living donor liver transplant volume. Although pretransplant mortality has improved after the recent policy change prioritizing pediatric donors for pediatric recipients, still, in 2022, 50 children died or were removed from the waiting list for being too sick to undergo transplant. Posttransplant mortality among pediatric liver transplant recipients remained notable, with death occurring in 4.0% at 6 months, 6.0% at 1 year, 8.2% at 3 years, 9.8% at 5 years, and 13.9% at 10 years. Similar to adult living donor recipients, pediatric living donor recipients had better 5-year patient survival compared with deceased donor recipients.

Management of alcohol-associated liver disease and alcohol use disorder in liver transplant candidates and recipients: Challenges and opportunities.

Alcohol-associated liver disease poses a significant global health burden, with rising alcohol consumption and prevalence of alcohol use disorder (AUD) contributing to increased morbidity and mortality. This review examines the challenges and opportunities in the care of candidates and recipients of liver transplant (LT) with AUD. Despite advancements in posttransplant patient survival, the risk of disease recurrence and alcohol relapse remains substantial. Several challenges have been identified, including (1) rising disease burden of alcohol-associated liver disease, variable transplant practices, and systemic barriers; (2) disparities in mental health therapy access and the impact on transplant; (3) variable definitions, underdiagnosis, and stigma affecting access to care; and (4) post-LT relapse, its risk factors, and consequential harm. The review focuses on the opportunities to improve AUD care for candidates and recipients of LT through effective biochemical monitoring, behavioral and pharmacologic approaches, creating Centers of Excellence for post-LT AUD care, advocating for policy reforms, and ensuring insurance coverage for necessary services as essential steps toward improving patient outcomes. The review also highlights unmet needs, such as the scarcity of addiction specialists, and calls for further research on personalized behavioral treatments, digital health, and value-based care models to optimize AUD care in the LT setting.

Excess waitlist mortality among candidates for multivisceral liver-intestine transplant in acuity circle allocation.

Candidates for multivisceral transplant (MVT) have experienced decreased access to transplant in recent years. Using Organ Procurement and Transplantation Network data, transplant and waiting list outcomes for MVT (ie, liver-intestine, liver-intestine-pancreas, and liver-intestine-kidney-pancreas) candidates listed between February 4, 2018, and February 3, 2022, were analyzed, including model for end-stage liver disease/pediatric end-stage liver disease and exception scores by era (before and after acuity circle [AC] implementation on February 4, 2020) and age group (pediatric and adult). Of 284 MVT waitlist registrations (45.6% pediatric), fewer had exception points at listing post-AC compared to pre-AC (10.0% vs 19.1%), and they were less likely to receive transplant (19.1% vs 35.9% at 90 days; 35.7% vs 57.2% at 1 year). Of 177 MVT recipients, exception points at transplant were more common post-AC compared to pre-AC (30.8% vs 20.2%). Postpolicy, adult MVT candidates were more likely to be removed due to death/too sick compared with liver-alone candidates (13.5% vs 5.6% at 90 days; 24.2% vs 9.8% at 1 year), whereas no excess waitlist mortality was observed among pediatric MVT candidates. Under current allocation policy, multivisceral candidates experience inferior waitlist outcomes compared with liver-alone candidates. Clarification of guidance around submission and approval of multivisceral exception requests may help improve their access to transplantation and achieve equity between multivisceral and liver-alone candidates on the liver transplant waiting list.

Summary of a consensus conference on heart-liver transplantation.

Patients with severe heart disease may have coexisting liver disease from various causes. The incidence of combined heart-liver transplant (CHLT) is increasing as more patients with congenital heart disease survive to adulthood and develop advanced heart failure with associated liver disease from chronic right-sided heart or Fontan failure. However, the criteria for CHLT have not been established. To address this unmet need, a virtual consensus conference was organized on June 10, 2022, endorsed by the American Society of Transplantation. The conference represented a collaborative effort by experts in cardiothoracic and liver transplantation from across the United States to assess interdisciplinary criteria for liver transplantation in the CHLT candidate, surgical considerations of CHLT, current allocation system that generally results in the liver following the heart for CHLT, and optimal post-CHLT management. The conference served as a forum to unify criteria between the different specialties and to forge a pathway for patients who may need dual organ transplantation. Due to the continuing shortage of available donor organs, ethical issues related to multiorgan transplantation were also debated. The findings and consensus statements are presented.

Decreased Utilization Rate of Grafts for Liver Transplantation After Implementation of Acuity Circle-based Allocation.

BACKGROUND: The allocation system for livers began using acuity circles (AC) in 2020. In this study, we sought to evaluate the impact of AC policy on the utilization rate for liver transplantation (LT). METHODS: Using the US national registry data between 2018 and 2022, LTs were equally divided into 2 eras: pre-AC (before February 4, 2020) and post-AC (February 4, 2020, and after). Deceased potential liver donors were defined as deceased donors from whom at least 1 organ was procured. RESULTS: The annual number of deceased potential liver donors increased post-AC (from 10 423 to 12 259), approaching equal to that of new waitlist registrations for LT (n = 12 801). Although the discard risk index of liver grafts was comparable between the pre- and post-AC eras, liver utilization rates in donation after brain death (DBD) and donation after circulatory death (DCD) donors were lower post-AC ( P < 0.01; 79.8% versus 83.4% and 23.7% versus 26.0%, respectively). Recipient factors, ie, no recipient located, recipient determined unsuitable, or time constraints, were more likely to be reasons for nonutilization after implementation of the AC allocation system compared to the pre-AC era (20.0% versus 12.3% for DBD donors and 50.1% versus 40.8% for DCD donors). Among non-high-volume centers, centers with lower utilization of marginal DBD donors or DCD donors were more likely to decrease LT volume post-AC. CONCLUSIONS: Although the number of deceased potential liver donors has increased, overall liver utilization among deceased donors has decreased in the post-AC era. To maximize the donor pool for LT, future efforts should target specific reasons for liver nonutilization.

Implementation of a National Liver Review Board for exception requests in the United States: A 2-year monitoring report.

The exception point system for liver allocation in the United States allows for additional waitlist priority for candidates where the Model for End-Stage Liver Disease or Pediatric End-stage Liver Disease does not effectively represent their urgency or need for a transplant. In May 2019, the review process for liver exception cases transitioned from 11 Regional Review Boards (RRBs) to 1 National Liver Review Board (NLRB), intended to increase consistency nationwide, improve efficiency, and balance transplant access for candidates with and without exception scores. This report provides a review of liver exception request and review practices, waitlist outcomes, and transplant activity in the first 2 years after implementation of the NLRB and acuity circle-based distribution in the United States. We compared initial and extension exception request forms submitted from May 13, 2017 to May 13, 2019 (prepolicy or RRB era) to the period from February 4, 2020 to February 3, 2022 (postpolicy or NLRB era). During this time, the NLRB reviewed 10,083 initial exception requests and 12,686 extension requests. Notable postpolicy highlights include (1) an increase in the proportion of initial and extension requests that were automatically approved instead of manually reviewed; (2) a decrease in the overall approval rates of initial exception requests (87.8% for adult HCC, 64.3% for adult other diagnoses, and 71.5% for pediatric); and (3) reduction in the time from exception request submission to adjudication to a median of 3.73 days. The proportions of waitlist registration and deceased donor liver transplants for patients with exception scores decreased, and waitlist outcomes between patients with and without exception scores are now comparable. Implementation of the NLRB improved efficiency, reduced case workloads, and standardized criteria for exception cases, with similar waitlist outcomes between patients with and without exception scores and improved equity in terms of access to liver transplants.

Cost-effectiveness analysis of interventional liver-directed therapies for downstaging of HCC before liver transplant.

Transarterial chemoembolization (TACE) and transarterial radioembolization (TARE) are the 2 most used modalities for patients with HCC while awaiting liver transplant. The purpose of this study is to perform a cost-effectiveness analysis comparing TACE and TARE for downstaging (DS) patients with HCC. A cost-effectiveness analysis was performed comparing TACE and TARE in DS HCC over a 5-year time horizon from a payer's perspective. The clinical course, including those who achieved successful DS leading to liver transplant and those who failed DS with possible disease progression, was obtained from the United Network for Organ Sharing. Costs and effectiveness were measured in US dollars and quality-adjusted life years (QALYs). Probabilistic and deterministic sensitivity analyses were performed. TARE achieved a higher effectiveness of 2.51 QALY (TACE: 2.29 QALY) at a higher cost of $172,162 (TACE: $159,706), with the incremental cost-effectiveness ratio of $55,964/QALY, making TARE the more cost-effective strategy. The difference in outcome was equivalent to 104 days (nearly 3.5 months) in compensated cirrhosis state. Probabilistic sensitivity analyses showed that TARE was more cost-effective in 91.69% of 10,000 Monte Carlo simulations. TARE was more effective if greater than 48.2% of patients who received TACE or TARE were successfully downstaged (base case: 74.6% from the pooled analysis of multiple published cohorts). TARE became more cost-effective when the cost of TACE exceeded $4,831 (base case: $12,722) or when the cost of TARE was lower than $43,542 (base case: $30,609). Subgroup analyses identified TARE to be the more cost-effective strategy if the TARE cohort required 1 fewer locoregional therapy than the TACE cohort. TARE is the more cost-effective DS strategy for patients with HCC exceeding Milan criteria compared to TACE.

Overcoming the hurdles of steatotic grafts in liver transplantation: Insights into survival and prognostic factors.

With increasing metabolic dysfunction-associated steatotic liver disease, the use of steatotic grafts in liver transplantation (LT) and their impact on postoperative graft survival (GS) needs further exploration. Analyzing adult LT recipient data (2002-2022) from the United Network for Organ Sharing database, outcomes of LT using steatotic (≥30% macrosteatosis) and nonsteatotic donor livers, donors after circulatory death, and standard-risk older donors (age 45-50) were compared. GS predictors were evaluated using Kaplan-Meier and Cox regression analyses. Of the 35,345 LT donors, 8.9% (3,155) were fatty livers. The initial 30-day postoperative period revealed significant challenges with fatty livers, demonstrating inferior GS. However, the GS discrepancy between fatty and nonfatty livers subsided over time ( p = 0.10 at 5 y). Long-term GS outcomes showed comparable or even superior results in fatty livers relative to nonsteatotic livers, conditional on surviving the initial 90 postoperative days ( p = 0.90 at 1 y) or 1 year ( p = 0.03 at 5 y). In the multivariable Cox regression analysis, the high body surface area (BSA) ratio (≥1.1) (HR 1.42, p = 0.02), calculated as donor BSA divided by recipient BSA, long cold ischemic time (≥6.5 h) (HR 1.72, p < 0.01), and recipient medical condition (intensive care unit hospitalization) (HR 2.53, p < 0.01) emerged as significant adverse prognostic factors. Young (<40 y) fatty donors showed a high BSA ratio, diabetes, and intensive care unit hospitalization as significant indicators of a worse prognosis ( p < 0.01). Our study emphasizes the initial postoperative 30-day survival challenge in LT using fatty livers. However, with careful donor-recipient matching, for example, avoiding the use of steatotic donors with long cold ischemic time and high BSA ratios for recipients in the intensive care unit, it is possible to enhance immediate GS, and in a longer time, outcomes comparable to those using nonfatty livers, donors after circulatory death livers, or standard-risk older donors can be anticipated. These novel insights into decision-making criteria for steatotic liver use provide invaluable guidance for clinicians.

Breaking distance barriers in liver transplantation: Risk factors and outcomes of long-distance liver grafts.

BACKGROUND: Long-distance-traveling liver grafts in liver transplantation present challenges due to prolonged cold ischemic time and increased risk of ischemia-reperfusion injury. We identified long-distance-traveling liver graft donor and recipient characteristics and risk factors associated with long-distance-traveling liver graft use. METHODS: We conducted a retrospective analysis of data from donor liver transplantation patients registered from 2014 to 2020 in the United Network for Organ Sharing registry database. Donor, recipient, and transplant factors of graft survival were compared between short-travel grafts and long-distance-traveling liver grafts (traveled >500 miles). RESULTS: During the study period, 28,265 patients received a donation after brainstem death liver transplantation and 3,250 a donation after circulatory death liver transplantation. The long-distance-traveling liver graft rate was 6.2% in donation after brainstem death liver transplantation and 7.1% in donation after circulatory death liver transplantation. The 90-day graft survival rates were significantly worse for long-distance-traveling liver grafts (donation after brainstem death: 95.7% vs 94.5%, donation after circulatory death: 94.5% vs 93.9%). The 3-year graft survival rates were similar for long-distance-traveling liver grafts (donation after brainstem death: 85.5% vs 85.1%, donation after circulatory death: 81.0% vs 80.4%). Cubic spline regression analyses revealed that travel distance did not linearly worsen the prognosis of 3-year graft survival. On the other hand, younger donor age, lower donor body mass index, and shorter cold ischemic time mitigated the negative impact of 90-day graft survival in long-distance-traveling liver grafts. CONCLUSION: The use of long-distance-traveling liver grafts negatively impacts 90-day graft survival but not 3-year graft survival. Moreover, long-distance-traveling liver grafts are more feasible with appropriate donor and recipient factors offsetting the extended cold ischemic time. Mechanical perfusion can improve long-distance-traveling liver graft use. Enhanced collaboration between organ procurement organizations and transplant centers and optimized transportation systems are essential for increasing long-distance-traveling liver graft use, ultimately expanding the donor pool.

The short and long-term prognostic influences of liver grafts with high bilirubin levels at the time of organ recovery.

BACKGROUND: Donors with hyperbilirubinemia are often not utilized for liver transplantation (LT) due to concerns about potential liver dysfunction and graft survival. The potential to mitigate organ shortages using such donors remains unclear. METHODS: This study analyzed adult deceased donor data from the United Network for Organ Sharing database (2002-2022). Hyperbilirubinemia was categorized as high total bilirubin (3.0-5.0 mg/dL) and very high bilirubin (≥5.0 mg/dL) in brain-dead donors. We assessed the impact of donor hyperbilirubinemia on 3-month and 3-year graft survival, comparing these outcomes to donors after circulatory death (DCD). RESULTS: Of 138 622 donors, 3452 (2.5%) had high bilirubin and 1999 (1.4%) had very high bilirubin levels. Utilization rates for normal, high, and very high bilirubin groups were 73.5%, 56.4%, and 29.2%, respectively. No significant differences were found in 3-month and 3-year graft survival between groups. Donors with high bilirubin had superior 3-year graft survival compared to DCD (hazard ratio .83, p = .02). Factors associated with inferior short-term graft survival included recipient medical condition in intensive care unit (ICU) and longer cold ischemic time; factors associated with inferior long-term graft survival included older donor age, recipient medical condition in ICU, older recipient age, and longer cold ischemic time. Donors with ≥10% macrosteatosis in the very high bilirubin group were also associated with worse 3-year graft survival (p = .04). DISCUSSION: The study suggests that despite many grafts with hyperbilirubinemia being non-utilized, acceptable post-LT outcomes can be achieved using donors with hyperbilirubinemia. Careful selection may increase utilization and expand the donor pool without negatively affecting graft outcome.

Alcohol Use in Liver Transplant Recipients With Alcohol-related Liver Disease: A Comparative Assessment of Relapse Prediction Models.

BACKGROUND: The selection of liver transplant (LT) candidates with alcohol-related liver disease (ALD) is influenced by the risk of alcohol relapse (AR), yet the ability to predict AR is limited. We evaluate psychosocial factors associated with post-LT AR and compare the performance of high-risk alcoholism risk (HRAR), sustained alcohol use post-LT (SALT), and the Stanford Integrated Psychosocial Assessment for Transplantation (SIPAT) scores in predicting relapse. METHODS: A retrospective analysis of ALD patients undergoing LT from 2015 to 2021 at a single US transplant center was performed. Risk factors associated with post-LT AR were evaluated and test characteristics of 3 prediction models were compared. RESULTS: Of 219 ALD LT recipients, 23 (11%) had AR during a median study follow-up of 37.5 mo. On multivariate analysis, comorbid psychiatric illness (odds ratio 5.22) and continued alcohol use after advice from a health care provider (odds ratio 3.8) were found to be significantly associated with post-LT AR. On sensitivity analysis, SIPAT of 30 was optimal on discriminating between ALD LT recipients with and without post-LT AR. SIPAT outperformed both the HRAR and SALT scores (c-statistic 0.67 versus 0.59 and 0.62, respectively) in identifying post-LT AR. However, all scores had poor positive predictive value (<25%). CONCLUSIONS: AR after LT is associated with comorbid psychiatric illness and lack of heeding health care provider advice to abstain from alcohol. Although SIPAT outperformed the HRAR and SALT scores in predicting AR, all are poor predictors. The current tools to predict post-LT AR should not be used to exclude LT candidacy.

Hepatitis C Screening in Post-Baby Boomer Generation Americans: One Size Does Not Fit All.

OBJECTIVES: To analyze the impact of access to routine health care, as estimated by health insurance coverage, on hepatitis C virus (HCV) infection prevalence in US adults born after 1965 (post-baby boomer birth cohort [post-BBBC]) and to use the data to formulate strategies to optimize population screening for HCV. PATIENTS AND METHODS: Adult examinees in the National Health and Nutrition Examination Survey with available anti-HCV data were divided into era 1 (1999-2008) and era 2 (2009-2016). The prevalence of HCV infection, as defined by detectable serum HCV RNA, was determined in post-BBBC adults. In low prevalence groups, prescreening modalities were considered to increase the pretest probability. RESULTS: Of 16,966 eligible post-BBBC examinees, 0.5% had HCV infection. In both eras, more than 50% had no insurance. In era 2, HCV prevalence was 0.26% and 0.83% in those with and without insurance, respectively (P<.01). As a prescreening test, low alanine aminotransferase level (<23 U/L in women and 32 U/L in men) would identify 54% of post-BBBC adults with an extremely low (0.02%) HCV prevalence. Based on these data, a tiered approach that tests all uninsured directly for HCV and prescreens the insured with alanine aminotransferase would reduce the number to test by 56.5 million while missing less than 1% infections. CONCLUSION: For HCV elimination, passive "universal" screening in routine health care settings is insufficient, although the efficiency of screening may be improved with alanine aminotransferase prescreening. Importantly, for individuals with limited access to health care, proactive outreach programs for HCV screening are still needed.

Has the risk of liver re-transplantation improved over the two decades?

BACKGROUND: Despite advancements in liver transplantation (LT) over the past two decades, liver re-transplantation (re-LT) presents challenges. This study aimed to assess improvements in re-LT outcomes and contributing factors. METHODS: Data from the United Network for Organ Sharing database (2002-2021) were analyzed, with recipients categorized into four-year intervals. Trends in re-LT characteristics and postoperative outcomes were evaluated. RESULTS: Of 128,462 LT patients, 7254 received re-LT. Graft survival (GS) for re-LT improved (91.3%, 82.1%, and 70.8% at 30 days, 1 year, and 3 years post-LT from 2018 to 2021). However, hazard ratios (HRs) for GS remained elevated compared to marginal donors including donors after circulatory death (DCD), although the difference in HRs decreased in long-term GS. Changes in re-LT causes included a reduction in hepatitis C recurrence and an increase in graft failure post-primary LT involving DCD. Trends identified included recent decreased cold ischemic time (CIT) and increased distance from donor hospital in re-LT group. Meanwhile, DCD cohort exhibited less significant increase in distance and more marked decrease in CIT. The shortest CIT was recorded in urgent re-LT group. The highest Model for End-Stage Liver Disease score was observed in urgent re-LT group, while the lowest was recorded in DCD group. Analysis revealed shorter time interval between previous LT and re-listing, leading to worse outcomes, and varying primary graft failure causes influencing overall survival post-re-LT. DISCUSSION: While short-term re-LT outcomes improved, challenges persist compared to DCD. Further enhancements are required, with ongoing research focusing on optimizing risk stratification models and allocation systems for better LT outcomes.

Benchmarking clinical risk prediction algorithms with ensemble machine learning: An illustration of the superlearner algorithm for the non-invasive diagnosis of liver fibrosis in non-alcoholic fatty liver disease.

Background and Aims: Ensemble machine learning (ML) methods can combine many individual models into a single 'super' model using an optimal weighted combination. Here we demonstrate how an underutilized ensemble model, the superlearner, can be used as a benchmark for model performance in clinical risk prediction. We illustrate this by implementing a superlearner to predict liver fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). Methods: We trained a superlearner based on 23 demographic and clinical variables, with the goal of predicting stage 2 or higher liver fibrosis. The superlearner was trained on data from the Non-alcoholic steatohepatitis - clinical research network observational study (NASH-CRN, n=648), and validated using data from participants in a randomized trial for NASH ('FLINT' trial, n=270) and data from examinees with NAFLD who participated in the National Health and Nutrition Examination Survey (NHANES, n=1244). We compared the performance of the superlearner with existing models, including FIB-4, NFS, Forns, APRI, BARD and SAFE. Results: In the FLINT and NHANES validation sets, the superlearner (derived from 12 base models) discriminates patients with significant fibrosis from those without well, with AUCs of 0.79 (95% CI: 0.73-0.84) and 0.74 (95% CI: 0.68-0.79). Among the existing scores considered, the SAFE score performed similarly to the superlearner, and the superlearner and SAFE scores outperformed FIB-4, APRI, Forns, and BARD scores in the validation datasets. A superlearner model derived from 12 base models performed as well as one derived from 90 base models. Conclusions: The superlearner, thought of as the "best-in-class" ML prediction, performed better than most existing models commonly used in practice in detecting fibrotic NASH. The superlearner can be used to benchmark the performance of conventional clinical risk prediction models.

One size does not fit all: Differential benefits of simultaneous liver-kidney transplantation by eligibility criteria.

Standard eligibility criteria for simultaneous liver-kidney transplantation (SLK) are in place in the United States. We hypothesize that the benefit associated with SLK over liver transplant alone differs by patient, depending on the specific SLK criteria met. We analyzed a retrospective US cohort of 5446 adult liver transplant or SLK recipients between January 1, 2015, and December 31, 2018, who are potentially qualified for SLK. Exposure was a receipt of SLK. We tested effect modification by the specific SLK eligibility criteria met (end-stage kidney disease, acute kidney injury, chronic kidney disease, or unknown). The primary outcome was death within 1 year of a liver transplant. We used a modified Cox regression analysis containing an interaction term of SLK * time from transplant. Two hundred ten (9%) SLK recipients and 351 (11%) liver-alone recipients died in 1 year. In the overall population, SLK was associated with a mortality benefit over liver transplant on the day of the transplant, without adjustment [HR: 0.59 (95% CI, 0.46-0.76)] and with adjustment [aHR: 0.50 (95% CI, 0.35-0.71)]. However, when SLK eligibility criteria were included, only in patients with end-stage kidney disease was SLK associated with a sustained survival benefit at day 0 [HR: 0.17 (0.08-0.35)] up to 288 (95% CI, 120-649) days post-transplant. Benefit within the first year post-transplant associated with SLK over liver-alone transplantation was only pronounced in patients with end-stage kidney disease but not present in patients meeting other criteria for SLK. A "strict SLK liberal Safety Net" strategy may warrant consideration at the national policy level.