Sex-based disparities in liver transplant rates in the United States

EASL Clinical Practice Guidelines on liver transplantation

Liver transplantation (LT) is an established life-saving procedure. The field of LT has changed in the past 10 years from several perspectives, with the expansion of indications, transplantation of patients with acute-on-chronic liver failure, evolution of transplant oncology, the use of donations after cardiac death, new surgical techniques, and prioritisation of recipients on the waiting list. In addition, the advent of organ perfusion machines, the recognition of new forms of rejection, and the attention paid to the transition from paediatric to adult patients, have all improved the management of LT recipients. The purpose of the EASL guidelines presented here is not to cover all aspects of LT but to focus on developments since the previous EASL guidelines published in 2016.

Sex and Size Disparities in Access to Liver Transplant for Patients With Hepatocellular Carcinoma

Importance

Women on the liver transplant waiting list are less likely to undergo a transplant than men. Recent approaches to resolving this disparity have involved adjustments to Model for End-Stage Liver Disease (MELD) scoring, but this will not affect candidates who rely on exception scores rather than calculated MELD score, the majority of whom have hepatocellular carcinoma (HCC).

Objective

To evaluate the association between female sex, candidate size, and access to liver transplant among wait-listed patients with HCC.

Design, Setting, and Participants

This retrospective cohort study used US transplant registry data of all adult (aged ≥18 years) wait-listed liver transplant candidates receiving an HCC exception score between January 1, 2010, and March 2, 2023.

Exposure

Wait-listed liver transplant candidate sex.

Main Outcomes and Measures

The association of female sex with (1) deceased-donor liver transplant (DDLT) and (2) death or waiting list removal for health deterioration were estimated using multivariable competing-risks regression. Results with and without adjustment for candidate height and weight (mediators of the sex disparity) were compared.

Results

The cohort included 31 725 candidates with HCC (mean [SD] age at receipt of exception, 61.2 [7.1] years; 76.3% men). Compared with men, women had a lower 1-year cumulative incidence of DDLT (50.8% vs 54.0%; P < .001) and a higher 1-year cumulative incidence of death or delisting for health deterioration (16.2% vs 15.0%; P = .002). After adjustment, without accounting for size, women had a lower incidence of DDLT (subdistribution hazard ratio [SHR], 0.92; 95% CI, 0.89-0.95) and higher incidence of death or delisting (SHR, 1.06; 95% CI, 1.00-1.13) compared with men. When adjusting for candidate height and weight, there was no association of female sex with incidence of DDLT or death or delisting. However, at a height cutoff of 166 cm, short women compared with short men were still less likely to undergo a transplant (SHR, 0.93; 95% CI, 0.88-0.99).

Conclusions and Relevance

In this study, women with HCC were less likely to receive a DDLT and more likely to die while wait-listed than men with HCC; these differences were largely (but not entirely) explained by sex-based differences in candidate size. For candidates listed with exception scores, additional changes to allocation policy are needed to resolve the sex disparity, including solutions to improve access to size-matched donor livers for smaller candidates.

Inconsistent values and algorithmic fairness: a review of organ allocation priority systems in the United States

BACKGROUND

The Organ Procurement and Transplant Network (OPTN) Final Rule guides national organ transplantation policies, mandating equitable organ allocation and organ-specific priority stratification systems. Current allocation scores rely on mortality predictions.

METHODS

We examined the alignment between the ethical priorities across organ prioritization systems and the statistical design of the risk models in question. We searched PubMed for literature on organ allocation history, policy, and ethics in the United States.

RESULTS

We identified 127 relevant articles, covering kidney (19), liver (60), lung (24), and heart transplants (23), and transplant accessibility (1). Current risk scores emphasize model performance and overlook ethical concerns in variable selection. The inclusion of race, sex, and geographical limits as categorical variables lacks biological basis; therefore, blurring the line between evidence-based models and discrimination. Comprehensive ethical and equity evaluation of risk scores is lacking, with only limited discussion of the algorithmic fairness of the Model for End-Stage Liver Disease (MELD) and the Kidney Donor Risk Index (KDRI) in some literature. We uncovered the inconsistent ethical standards underlying organ allocation scores in the United States. Specifically, we highlighted the exception points in MELD, the inclusion of race in KDRI, the geographical limit in the Lung Allocation Score, and the inadequacy of risk stratification in the Heart Tier system, creating obstacles for medically underserved populations.

CONCLUSIONS

We encourage efforts to address statistical and ethical concerns in organ allocation models and urge standardization and transparency in policy development to ensure fairness, equitability, and evidence-based risk predictions.

Validation of MELD3.0 in 2 centers from different continents

BACKGROUND

MELD3.0 has been proposed to stratify patients on the liver transplant waiting list (WL) to reduce the historical disadvantage of women in accessing liver transplant. Our aim was to validate MELD3.0 in 2 unique populations.

METHODS

This study is a 2-center retrospective cohort study from Toronto, Canada, and Valencia, Spain, of all adults added to the liver transplant WL between 2015 and 2019. Listing indications whose short-term survival outcome is not adequately captured by the MELD score were excluded. All patients analyzed had a minimum follow-up of 3 months after inclusion in the WL.

RESULTS

Six hundred nineteen patients were included; 61% were male, with a mean age of 56 years. Mean MELD at inclusion was 18.00 ± 6.88, Model for End-Stage Liver Disease Sodium (MELDNa) 19.78 ± 7.00, and MELD3.0 20.25 ± 7.22. AUC to predict 90-day mortality on the WL was 0.879 (95% CI: 0.820, 0.939) for MELD, 0.921 (95% CI: 0.876, 0.967) for MELDNa, and 0.930 (95% CI: 0.888, 0.973) for MELD3.0. MELDNa and MELD3.0 were better predictors than MELD (p = 0.055 and p = 0.024, respectively), but MELD3.0 was not statistically superior to MELDNa (p = 0.144). The same was true when stratified by sex, although the difference between MELD3.0 and MELD was only significant for women (p = 0.032), while no statistical significance was found in either sex when compared with MELDNa. In women, AUC was 0.835 (95% CI: 0.744, 0.926) for MELD, 0.873 (95% CI: 0.785, 0.961) for MELDNa, and 0.886 (95% CI: 0.803, 0.970) for MELD3.0; differences for the comparison between AUC in women versus men for all 3 scores were nonsignificant. Compared to MELD, MELD3.0 was able to reclassify 146 patients (24%), the majority of whom belonged to the MELD 10-19 interval. Compared to MELDNa, it reclassified 68 patients (11%), most of them in the MELDNa 20-29 category.

CONCLUSIONS

MELD3.0 has been validated in centers with significant heterogeneity and offers the highest mortality prediction for women on the WL without disadvantaging men. However, in these cohorts, it was not superior to MELDNa.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Coronary artery calcium assessment on non-gated chest CT to optimize pre-operative cardiac screening in liver transplantation

BACKGROUND

Guidelines recommend standard pre-operative cardiac screening in all liver transplantation (LT) recipients, despite the relatively low prevalence of obstructive coronary artery disease. Most LT recipients often have non-gated computed tomography (CT) performed of the chest and abdomen. This study evaluated the ability of coronary artery calcification (CAC) assessment on consecutively available scans, to identify a selection of low-risk patients, in whom further cardiac imaging can be safely withheld.

METHODS

LT recipients with prior non-gated CT chest-abdomen were included. CAC was visually scored on a semi-quantitative ordinal scale. Stress myocardial perfusion, coronary CT angiography (CCTA) and invasive coronary angiography (ICA) were used as golden standard. The sensitivity and specificity of CAC to exclude and predict obstructive CAD were assessed. In addition, peri- and postoperative mortality and cardiac events were analyzed.

RESULTS

149 LT recipients (ranged 31-71 years) were included. In 75% of patients, no CAC and mild CAC could rule out obstructive CAD on CCTA and ICA with 100% certainty. The threshold of mild CAC had a sensitivity of 100% for both CCTA and ICA and a specificity of 91% and 68%, respectively. None of the patients with no or mild calcifications experienced peri- and post-operative cardiac events or died of cardiac causes.

CONCLUSION

Visual evaluation of CAC on prior non-gated CT can accurately and safely exclude obstructive CAD in LT recipients. Incorporation of these already available data can optimize cardiac screening, by safely withholding or correctly allocating dedicated cardiac imaging in LT recipients. Thereby, reducing patients' test burden and save health care expenses.

Sex disparity in liver allocation within Eurotransplant

In Eurotransplant, relatively more females than males die while waiting for liver transplantation, and relatively fewer females undergo transplantation. With adult liver transplantation candidates listed between 2007 and 2019 (n = 21 170), we study whether sex disparity is inherent to the model for end-stage liver disease (MELD) scoring system, or the indirect result of a small candidate body size limiting access to transplantation. Cox proportional hazard models are used to quantify the direct effect of sex on waitlist mortality, independent of the effect of sex through MELD scores, and the direct effect of sex on the transplantation rate, independent of the effect of sex through MELD and candidate body size. Adjusted waitlist mortality hazard ratios (HRs) for female sex are insignificant (HR: 1.03, 95% CI: 0.88-1.20). We thus lack evidence that MELD systematically underestimates waitlist mortality rates for females. Transplantation rates are 25% lower for females than males in unadjusted analyses (HR: 0.74, 95% CI: 0.71-0.77), but HRs become insignificant with adjustment for mediators (HR: 0.98, 95% CI: 0.93-1.04), most importantly candidate body size. Sex disparity in Eurotransplant thus appears to be largely a consequence of lower transplantation rates for females, which are explained by sex differences in body size.

FERI: A Multitask-based Fairness Achieving Algorithm with Applications to Fair Organ Transplantation

Liver transplantation often faces fairness challenges across subgroups defined by sensitive attributes such as age group, gender, and race/ethnicity. Machine learning models for outcome prediction can introduce additional biases. Therefore, we introduce Fairness through the Equitable Rate of Improvement in Multitask Learning (FERI) algorithm for fair predictions of graft failure risk in liver transplant patients. FERI constrains subgroup loss by balancing learning rates and preventing subgroup dominance in the training process. Our results show that FERI maintained high predictive accuracy with AUROC and AUPRC comparable to baseline models. More importantly, FERI demonstrated an ability to improve fairness without sacrificing accuracy. Specifically, for the gender, FERI reduced the demographic parity disparity by 71.74%, and for the age group, it decreased the equalized odds disparity by 40.46%. Therefore, the FERI algorithm advanced fairness-aware predictive modeling in healthcare and provides an invaluable tool for equitable healthcare systems.

Women Are Also Disadvantaged in Accessing Transplant Outside the United States: Analysis of the Spanish Liver Transplantation Registry

Sex inequities in liver transplantation (LT) have been documented in several, mostly US-based, studies. Our aim was to describe sex-related differences in access to LT in a system with short waiting times. All adult patients registered in the RETH-Spanish Liver Transplant Registry (2000-2022) for LT were included. Baseline demographics, presence of hepatocellular carcinoma, cause and severity of liver disease, time on the waiting list (WL), access to transplantation, and reasons for removal from the WL were assessed. 14,385 patients were analysed (77% men, 56.2 ± 8.7 years). Model for end-stage liver disease (MELD) score was reported for 5,475 patients (mean value: 16.6 ± 5.7). Women were less likely to receive a transplant than men (OR 0.78, 95% CI 0.63, 0.97) with a trend to a higher risk of exclusion for deterioration (HR 1.17, 95% CI 0.99, 1.38), despite similar disease severity. Women waited longer on the WL (198.6 ± 338.9 vs. 173.3 ± 285.5 days, p < 0.001). Recently, women's risk of dropout has reduced, concomitantly with shorter WL times. Even in countries with short waiting times, women are disadvantaged in LT. Policies directed at optimizing the whole LT network should be encouraged to guarantee a fair and equal access of all patients to this life saving resource.

Practical Considerations When Choosing Chemoembolization versus Radioembolization for Hepatocellular Carcinoma

Transarterial chemoembolization (TACE) and transarterial radioembolization (TARE) are common liver-directed therapies (LDTs) for unresectable HCC. While both deliver intra-arterial treatment directly to the site of the tumor, they differ in mechanisms of action and side effects. Several studies have compared their side effect profile, time to progression, and overall survival data, but often these lack practical considerations when choosing which treatment modality to use. Many factors can impact operator's choice for treatment, and the choice depends on treatment availability, cost, insurance coverage, operator's comfort level, patient-specific factors, tumor location, tumor biology, and disease stage. This review discusses survival data, time to progression data, as well as more practical patient and tumor characteristics for personalized LDT with TACE or TARE.

Changing trends in the etiology of liver transplantation in Turkiye: A multicenter study

Background and Aim

This study aimed to identify the indications for liver transplantation (LT) based on underlying etiology and to characterize the patients who underwent LT.

Materials and Methods

We conducted a multicenter cross-sectional observational study across 11 tertiary centers in Turkiye from 2010 to 2020. The study included 5,080 adult patients.

Results

The mean age of patients was 50.3±15.2 years, with a predominance of female patients (70%). Chronic viral hepatitis (46%) was the leading etiological factor, with Hepatitis B virus infection at 35%, followed by cryptogenic cirrhosis (24%), Hepatitis C virus infection (8%), and alcohol-related liver disease (ALD) (6%). Post-2015, there was a significant increase in both the number of liver transplants and the proportion of living donor liver transplants (p<0.001). A comparative analysis of patient characteristics before and after 2015 showed a significant decline in viral hepatitis-related LT (p<0.001), whereas fatty liver disease-related LT significantly increased (p<0.001).

Conclusion

Chronic viral hepatitis continues to be the primary indication for LT in Turkiye. However, the proportions of non-alcoholic fatty liver disease (NAFLD) and ALD-related LT have seen an upward trend over the years.

Spatial inequalities and non-linear association of continuous variables with mortality risk of liver transplantation in Iran: a retrospective cohort study

Liver transplantation is the second most common solid organ transplant and the best option for liver failure. Of course, patient survival after transplantation depends on many risk factors. The aim of this study was to investigate the spatial and non-linear effects of continuous risk factors on patient survival after liver transplantation. This retrospective cohort study (n = 3148) used data on liver transplantation in Iran (2004-2019). A generalized additive model with spatial effects and non-linear effects of age and Model for End-Stage Liver Disease (MELD) score variables by penalized spline was used. The majority of patients were male (63.3%), with a mean (SD) age of 42.65 (13.31) and a mean (SD) MELD score of 24.43 (6.72). The 1, 5, and 10-year survival rates were 88.2%, 84.6%, and 82.5% respectively. The non-linear effect showed a steeper slope of the age effect on the hazard of death after the age of 50 (p < 0.05), and the MELD score had a direct but non-linear relationship with the hazard of death (p < 0.05). In the spatial pattern, the provinces with a greater distance from the transplant center had significantly fewer old patients than other provinces. Also, more distant provinces with an older transplant age had higher post-transplant mortality rates. Our study showed that it is better to take age and MELD score into account in postoperative care. The spatial pattern of mortality risk reflects inequalities in access to transplantation and public health services after transplantation.

A transformer-based deep learning approach for fairly predicting post-liver transplant risk factors

Liver transplantation is a life-saving procedure for patients with end-stage liver disease. There are two main challenges in liver transplant: finding the best matching patient for a donor and ensuring transplant equity among different subpopulations. The current MELD scoring system evaluates a patient's mortality risk if not receiving an organ within 90 days. However, the donor-patient matching should also consider post-transplant risk factors, such as cardiovascular disease, chronic rejection, etc., which are all common complications after transplant. Accurate prediction of these risk scores remains a significant challenge. In this study, we used predictive models to solve the above challenges. Specifically, we proposed a deep learning model to predict multiple risk factors after a liver transplant. By formulating it as a multi-task learning problem, the proposed deep neural network was trained to simultaneously predict the five post-transplant risks and achieve equal good performance by exploiting task-balancing techniques. We also proposed a novel fairness-achieving algorithm to ensure prediction fairness across different subpopulations. We used electronic health records of 160,360 liver transplant patients, including demographic information, clinical variables, and laboratory values, collected from the liver transplant records of the United States from 1987 to 2018. The model's performance was evaluated using various performance metrics such as AUROC and AUPRC. Our experiment results highlighted the success of our multi-task model in achieving task balance while maintaining accuracy. The model significantly reduced the task discrepancy by 39 %. Further application of the fairness-achieving algorithm substantially reduced fairness disparity among all sensitive attributes (gender, age group, and race/ethnicity) in each risk factor. It underlined the potency of integrating fairness considerations into the task-balancing framework, ensuring robust and fair predictions across multiple tasks and diverse demographic groups.

Act Together and Act Now to Overcome Gender Disparity in Organ Transplantation

Gender disparity refers to the unequal treatment or a perception of individuals based on their gender and arises from differences in socially constructed gender roles. In the field of transplantation, gender inequality arises at different stages, affecting access to medical care, donation practices, and posttransplant followup care. Gender disparity in transplantation is not limited to any geographic region but is thought to be more prevalent in developing nations. An unusually high number of female donations with relatively fewer female recipients is not only attributable to the low economy but a congregation of medical, social, cultural, and psychological factors. Gender disparities can also be shown in transplant-related professional societies. This review highlights the complexities of spousal donation and vulnerability of women, especially in the developing world. There is a growing need to further modify transplant policies to tackle gender disparities, especially in living related donation. Systematic research in the context of gender-related concerns in transplantation will further aid in understanding the complexities and formulating policies for eliminating gender disparities. Gender disparity is a global problem and not merely limited to transplantation.

Sex-based Disparities in Access to Liver Transplantation for Waitlisted Patients With Model for End-stage Liver Disease Score of 40

OBJECTIVE

To determine the association of sex with access to liver transplantation among candidates with the highest possible model for end-stage liver disease score (MELD 40).

BACKGROUND

Women with end-stage liver disease are less likely than men to receive liver transplantation due in part to MELD's underestimation of renal dysfunction in women. The extent of the sex-based disparity among patients with high disease severity and equally high MELD scores is unclear.

METHODS

Using national transplant registry data, we compared liver offer acceptance (offers received at match MELD 40) and waitlist outcomes (transplant vs death/delisting) by sex for 7654 waitlisted liver transplant candidates from 2009 to 2019 who reached MELD 40. Multivariable logistic and competing-risks regression was used to estimate the association of sex with the outcome and adjust for the candidate and donor factors.

RESULTS

Women (N = 3019, 39.4%) spent equal time active at MELD 40 (median: 5 vs 5 days, P = 0.28) but had lower offer acceptance (9.2% vs 11.0%, P < 0.01) compared with men (N = 4635, 60.6%). Adjusting for candidate/donor factors, offers to women were less likely accepted (odds ratio = 0.87, P < 0.01). Adjusting for candidate factors, once they reached MELD 40, women were less likely to be transplanted (subdistribution hazard ratio = 0.90, P < 0.01) and more likely to die or be delisted (subdistribution hazard ratio = 1.14, P = 0.02).

CONCLUSIONS

Even among candidates with high disease severity and equally high MELD scores, women have reduced access to liver transplantation and worse outcomes compared with men. Policies addressing this disparity should consider factors beyond MELD score adjustments alone.

Mitigating Health Disparities in Transplantation Requires Equity, Not Equality

Despite decades of research and evidence-based mitigation strategies, disparities in access to transplantation persist for all organ types and in all stages of the transplant process. Although some strategies have shown promise for alleviating disparities, others have fallen short of the equity goal by providing the same tools and resources to all rather than tailoring the tools and resources to one's circumstances. Innovative solutions that engage all stakeholders are needed to achieve equity regardless of race, sex, age, socioeconomic status, or geography. Mitigation of disparities is paramount to ensure fair and equitable access for those with end-stage disease and to preserve the trust of the public, upon whom we rely for their willingness to donate organs. In this overview, we present a summary of recent literature demonstrating persistent disparities by stage in the transplant process, along with policies and interventions that have been implemented to combat these disparities and hypotheses for why some strategies have been more effective than others. We conclude with future directions that have been proposed by experts in the field and how these suggested strategies may help us finally arrive at equity in transplantation.

Survival benefit from liver transplantation for patients with and without hepatocellular carcinoma

Background & Aims

In the USA, inequal liver transplantation (LT) access exists between patients with and without hepatocellular carcinoma (HCC). Survival benefit considers survival without and with LT and could equalise LT access. We calculated bias-corrected LT survival benefit for patients with(out) HCC who underwent a transplant, based on longitudinal data in a recent United States cohort.

Methods

Adult LT candidates with(out) HCC between 2010 and 2019 were included. Waitlist survival over time was contrasted to post-transplant survival, to estimate 5-year survival benefit from the moment of LT. Waitlist survival was modelled with a bias-corrected Cox regression, and post-transplant survival was estimated through Cox proportional hazards regression.

Results

Mean HCC survival without LT was always lower than non-HCC waitlist survival. Below model for end-stage liver disease (sodium) (MELD(-Na)) 30, patients with HCC gained more life-years from LT than patients without HCC at the same MELD(-Na) score. Only patients without HCC below MELD(-Na) 9 had negative benefit. Most patients with HCC underwent a transplant below MELD(-Na) 14, and most patients without HCC underwent a transplant above MELD(-Na) 26. Liver function [MELD(-Na), albumin] was the main predictor of 5-year benefit. Therefore, during 5 years, most patients with HCC gained 0.12 to 1.96 years from LT, whereas most patients without HCC gained 2.48 to 3.45 years.

Conclusions

On an individual level, performing a transplant in patients with HCC resulted in survival benefit. However, on a population level, benefit was indirectly decreased, as patients without HCC were likely to gain more survival owing to decreased liver function. For patients who underwent a transplant, a constructed online calculator estimates 5-year survival benefit given specific patient characteristics. Survival benefit scores could serve to equalise LT access.

Impact and implications

Benefit is a comparison of the survival with and without liver transplantation, and it is important when deciding who should undergo a transplant. Liver function is most important when predicting possible benefit from transplantation. Patients with liver cancer die sooner on the waiting list than similar patients without liver cancer. However, patients with liver cancer more often have better liver function. Most patients without liver cancer derive more benefit from transplantation than patients with liver cancer.

Sex and racial disparities in living donor liver transplantation in the United States

Sex and racial disparities in deceased donor liver transplantation (DDLT) have been described, but this has not been well studied in living donor liver transplantation (LDLT). We aim to examine these disparities in the US LDLT population and identify potential predictors of these differences. From 2002 to 2021, the Organ Procurement and Transplant Network database was queried to characterize the adult LDLT population and evaluate differences between LDLT and DDLT recipients with regard to sex and race. Donor demographics, Model for End-stage Liver Disease (MELD), and socioeconomic data were all included. Of the 4961 LDLT and 99,984 DDLT recipients, males received the majority of LDLT (55% vs. 45%, p < 0.001) and DDLT (67% vs. 33%, p < 0.001) compared to females. There was a significant difference in race between male and female LDLT recipients ( p < 0.001); 84% of male recipients were White and 78% of females. In both groups, females had lower levels of education and were less likely to have private insurance. There were more female living donors (N = 2545, 51%); 50% of female donors donated to males but only 40% of males donated to females. Donor-recipient relationships varied significantly by sex ( p < 0.001); males received more donations from spouses (62% vs. 39%) and siblings (60% vs. 40%). In the LDLT population, significant disparities exist with respect to sex and race that disadvantage women, but these disparities are less pronounced than in the DDLT population. Although further studies are needed, complex clinical and socioeconomic differences as well as donor factors may explain these variations.

COVID-19 and severity of liver diseases: Possible crosstalk and clinical implications

COVID-19-infected individuals and those who recovered from the infection have been demonstrated to have elevated liver enzymes or abnormal liver biochemistries, particularly with preexisting liver diseases, liver metabolic disorders, viral hepatitis, and other hepatic comorbidities. However, possible crosstalk and intricate interplay between COVID-19 and liver disease severity are still elusive, and the available data are murky and confined. Similarly, the syndemic of other blood-borne infectious diseases, chemical-induced liver injuries, and chronic hepatic diseases continued to take lives while showing signs of worsening due to the COVID-19 crisis. Moreover, the pandemic is not over yet and is transitioning to becoming an epidemic in recent years; hence, monitoring liver function tests (LFTs) and assessing hepatic consequences of COVID-19 in patients with or without liver illnesses would be of paramount interest. This pragmatic review explores the correlations between COVID-19 and liver disease severity based on abnormal liver biochemistries and other possible mechanisms in individuals of all ages from the emergence of the COVID-19 pandemic to the post-pandemic period. The review also alludes to clinical perspectives of such interactions to curb overlapping hepatic diseases in people who recovered from the infection or living with long COVID-19.

Association of Body Surface Area With Access to Deceased Donor Liver Transplant and Novel Allocation Policies

Importance

Small waitlist candidates are significantly less likely than larger candidates to receive a liver transplant.

Objective

To investigate the magnitude of the size disparity and test potential policy solutions.

Design, Setting, and Participants

A decision analytical model was generated to match liver transplant donors to waitlist candidates based on predefined body surface area (BSA) ratio limits (donor BSA divided by recipient BSA). Participants included adult deceased liver transplant donors and waitlist candidates in the Organ Procurement and Transplantation Network database from June 18, 2013, to March 20, 2020. Data were analyzed from January 2021 to September 2021.

Exposures

Candidates were categorized into 6 groups according to BSA from smallest (group 1) to largest (group 6). Waitlist outcomes were examined. A match run was created for each donor under the current acuity circle liver allocation policy, and the proportion of candidates eligible for a liver based on BSA ratio was calculated. Novel allocation models were then tested.

Main Outcomes and Measures

Time on the waitlist, assigned Model for End-Stage Liver Disease (MELD) score, and proportion of patients undergoing a transplant were compared by BSA group. Modeling under the current allocation policies was used to determine baseline access to transplant by group. Simulation of novel allocation policies was performed to examine change in access.

Results

There were 41 341 donors (24 842 [60.1%] male and 16 499 [39.9%] female) and 84 201 waitlist candidates (53 724 [63.8%] male and 30 477 [36.2%] female) in the study. The median age of the donors was 42 years (IQR, 28-55) and waitlist candidates, 57 years (IQR, 50-63). Females were overrepresented in the 2 smallest BSA groups (7100 [84.0%] and 7922 [61.1%] in groups 1 and 2, respectively). For each increase in group number, waitlist time decreased (234 days [IQR, 48-700] for group 1 vs 179 days [IQR, 26-503] for group 6; P < .001) and the proportion of the group undergoing transplant likewise improved (3890 [46%] in group 1 vs 4932 [57%] in group 6; P < .001). The smallest 2 groups of candidates were disadvantaged under the current acuity circle allocation model, with 37% and 7.4% fewer livers allocated relative to their proportional representation on the waitlist. Allocation of the smallest 10% of donors (by BSA) to the smallest 15% of candidates overcame this disparity, as did performing split liver transplants.

Conclusions and Relevance

In this study, liver waitlist candidates with the smallest BSAs had a disadvantage due to size. Prioritizing allocation of smaller liver donors to smaller candidates may help overcome this disparity.

Addressing sex-based disparities in liver transplantation

PURPOSE OF REVIEW

Disparities in access to liver transplantation by sex have been well described, disadvantaging women. Understanding the multifactorial causes of these disparities as well as the variety of proposed solutions is critical to improving access to this life-saving intervention for women. This review aims to summarize the current body of evidence on observed sex disparities in liver transplantation and highlight actionable, evidence-based mechanisms by which these disparities can be addressed.

RECENT FINDINGS

Strategies for addressing sex disparities in liver transplantation include increasing organ utilization, changing allocation policy, and leveraging public policies to reduce the incidence of end-stage liver disease. Several other promising interventions are currently being explored.

SUMMARY

In the United States, women face additional barriers to liver transplantation on the basis of sex. Immediate action is necessary to systematically address these inequities.

Mortality in patients with end-stage liver disease above model for end-stage liver disease 3.0 of 40

BACKGROUND AND AIMS

Since the implementation of the model for end-stage liver disease (MELD) score to determine waitlist priority for liver transplant (LT) in 2002, the score has been capped at 40. Recently, the MELD 3.0 score was proposed to improve upon MELD-Na. Here, we examine waitlist mortality and LT outcomes in patients with MELD 3.0 ≥ 40 to assess the potential impact of uncapping the score.

APPROACH AND RESULTS

Adult waitlist registrations for LT from January 2016 to December 2021 were identified in the registry data from the Organ Procurement and Transplant Network. All MELD 3.0 scores were calculated at registration and thereafter. Waitlist mortality for up to 30 days was calculated as well as post-LT survival. There were 54,060 new waitlist registrations during the study period, of whom 2820 (5.2%) had MELD 3.0 ≥ 40 at listing. The 30-day waitlist mortality was high in these patients, yet it increased further in proportion with MELD 3.0 up to a score of 55 with 30-day mortality of 58.3% for MELD 3.0 of 40-44 and 82.4% for ≥50. The multivariable hazard ratio was 1.13 for each point of MELD 3.0, adjusting for several variables including acute-on-chronic liver failure. The number of LT recipients with MELD 40 at transplant increased from 155 in 2002 to 752 in 2021. Posttransplant survival was comparable across MELD strata including MELD of 35-39.

CONCLUSION

MELD 3.0 scores beyond 40 are associated with increasing waitlist mortality without adversely affecting posttransplant outcome. Uncapping the MELD score in waitlist candidates may lead to greater survival benefit from LT.

Donor, Recipient and Surgeon Sex and Sex-Concordance and their Impact on Liver Transplant Outcome

(1) Background: Patient sex is associated with differential outcome of many procedures although the exact mechanisms remain unknown. Especially in transplant surgery, surgeon-patient sex-concordance is rarely present for female patients and outcome may be negatively affected. (2) Methods: In this single-center retrospective cohort study, recipient, donor, and surgeon sex were evaluated and short- and long-term outcome was analyzed with regards to sex and sex-concordance of patients, donors, and surgeons. (3) Results: We included 425 recipients in our study; 50.1% of organ donors, 32.7% of recipients, and 13.9% of surgeons were female. Recipient-donor sex concordance was present in 82.7% of female recipients and in 65.7% of male recipients (p = 0.0002). Recipient-surgeon sex concordance was present in 11.5% of female recipients and in 85.0% of male recipients (p < 0.0001). Five-year patient survival was comparable between female and male recipients (70.0% vs. 73.3%, p = 0.3978). Five-year patient survival of female recipients treated by female surgeons was improved without reaching significance (81.3% vs. 68.4%, p = 0.3621). (4) Conclusions: Female recipients and female surgeons are underrepresented in liver transplant surgery. Societal factors influencing outcome of female patients suffering from end-stage organ failure need to be further examined and acted upon to possibly improve the outcome of female liver transplant recipients.

The fundamentals of sex-based disparity in liver transplantation: Understanding can lead to change

Liver transplantation (LT) is the definitive treatment for end-stage liver disease. Unfortunately, women are disadvantaged at every stage of the LT process. We conducted a literature review to increase the understanding of this disparity. Hormonal differences, psychological factors, and Model for End-Stage Liver Disease (MELD) score inequalities are some pretransplantation factors that contribute to this disparity. In the posttransplantation setting, women have differing risk than men in most major outcomes (perioperative complications, rejection, long-term renal dysfunction, and malignancy) and assessing the two groups together is disadvantageous. Herein, we propose interventions including standardized criteria for LT referral, using an alternate MELD, education for support of women, and motivating women to seek living donors. Understanding sex-based differences will allow us to improve access, tailor management, and improve overall outcomes for all patients, particularly women.

Disparities in Social Determinants of Health Among Patients Receiving Liver Transplant: Analysis of the National Inpatient Sample From 2016 to 2019

Background

Liver transplantation is the life-saving standard of care for those with end-stage liver disease. Unfortunately, many patients on the liver transplant list die waiting. Several studies have demonstrated significant differences based on disparities in race, gender, and multiple socioeconomic factors. We sought to evaluate recent disparities among patients receiving liver transplants using the latest available data from the National Inpatient Sample (NIS), the largest publicly available inpatient care database in the United States.

Methods

We performed an analysis of discharge data from the NIS between 2016 and 2019. We identified adult patients with chronic liver disease who underwent a liver transplant using the International Classification of Diseases, 10th revision (ICD-10) codes. Multivariate logistic regression was used to adjust for differences in race, gender, socioeconomic status, and comorbidities among those who received a liver transplant.

Results

A total of 24,595 liver transplants were performed over the study period. Female gender was independently associated with decreased transplant rates (adjusted odds ratio (AOR) 0.83, 95% confidence interval (CI), 0.78-0.89, P < 0.001). Compared to White patients, Black patients had decreased transplant rates (AOR 0.86, 95% CI, 0.75-0.99, P = 0.034), as did Native Americans (AOR 0.64; 95% CI, 0.42-0.97, P = 0.035). Hispanics and Asian Americans had increased rates of liver transplantation (AOR 1.16, 95% CI 1.02-1.32, P = 0.022, and 1.36, 95% CI 1.11-1.67, P = 0.003; respectively). The increase in income quartile was associated with an incremental increase in transplant rates. Additionally, patients with private insurance had much higher transplant rates compared to those with Medicare (AOR 2.50, 95% CI 2.31-2.70, P < 0.001) while patients without insurance had the lowest rates of transplantation (AOR 0.18, 95% CI 0.12-0.28, P < 0.001).

Conclusions

Our analysis demonstrates that race, gender, and other social determinants of health have significant impacts on the likelihood of receiving a liver transplant. Our study, on a national level, confirms previously described disparities in receiving liver transplantation. Patient-level studies are needed to better understand how these variables translate into differing liver transplantation rates.

Sex Disparities in Outcome of Patients with Alcohol-Related Liver Cirrhosis within the Eurotransplant Network—A Competing Risk Analysis

Alcohol use disorder (AUD) is one of the most important risk factors for the development of alcohol-related liver cirrhosis (ALC). Importantly, psychiatrists are an integral part of the interdisciplinary care for patients with AUD and ALC. The aim of the current study was to investigate whether sex influences the outcome within this group of patients. For this purpose, data of all registrations for liver transplantations due to ALC within the Eurotransplant region from 2010 to 2019 were analyzed for sex disparities using competing risk models and in-between group comparisons. Relevant sex differences in registration numbers (24.8% female) and investigated outcomes were revealed. Risk ratios for a positive outcome, i.e., transplantation (0.74), and those of adverse outcomes, i.e., removal from waiting list (1.44) and death on waiting list (1.10), indicated a relative disadvantage for female patients with ALC. Further, women listed for liver transplantations were significantly younger than their male counterparts. Notably, sex disparities found in registration and outcome parameters were independent of differences found in the prevalence of AUD and liver transplantations. Further research is necessary to identify the underlying mechanisms and establish strategies to ensure equity and utility in liver transplantations due to ALC.

"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.

Survival Benefit of Split-Liver Transplantation for Pediatric and Adult Candidates

Patient and graft survival are similar following whole-liver transplantations (WLTs) versus split-liver transplantations (SLTs) among pediatric and adult recipients, yet SLTs are rarely used. We sought to determine the survival benefit associated with accepting a splittable graft offer for SLT versus declining and waiting for a subsequent offer using 2010 to 2018 Scientific Registry of Transplant Recipients (SRTR) data on 928 pediatric and 1814 adult liver transplantation candidates who were ever offered a splittable graft. We compared eventual mortality, regardless of subsequent transplants, between those patients who accepted versus declined a split liver offer with adjustments for Pediatric End-Stage Liver Disease/Model for End-Stage Liver Disease (MELD) scores, diagnosis, and weight among pediatric candidates and matching for MELD score, height, and offer among adult candidates. Among pediatric candidates ≤7 kg, split liver offer acceptance versus decline was associated with a 63% reduction in mortality (adjusted hazard ratio [aHR], _0.17 0.37_0.80 [P = 0.01]; 93.1% versus 84.0% 1-year survival after decision). Within 1 year of decline for those ≤7 kg, 6.4% died and 31.1% received a WLT. Among pediatric candidates >7 kg, there was no significant difference associated with acceptance of a split liver offer (aHR, _0.63 1.07_1.82 [P = 0.81]; 91.7% versus 94.4% 1-year survival after decision). Within 1 year of decline for those >7 kg, 1.8% died and 45.8% received a WLT. Among adult candidates, split liver offer acceptance was associated with a 43% reduction in mortality (aHR, _0.39 0.57_0.83 [P = 0.005]; 92.2% versus 84.4% 1-year survival after decision). Within 1 year of decline for adult candidates, 7.9% died and 39.3% received a WLT. Accepting split liver offers for SLT could significantly improve survival for small children and adults on the waiting list.

Are MELD and MELDNa Still Reliable Tools to Predict Mortality on the Liver Transplant Waiting List?

Liver transplantation is the only curative treatment for end-stage liver disease. Unfortunately, the scarcity of donor organs and the increasing pool of potential recipients limit access to this life-saving procedure. Allocation should account for medical and ethical factors, ensuring equal access to transplantation regardless of recipient's gender, race, religion, or income. Based on their short-term prognosis prediction, model for end-stage liver disease (MELD) and MELD sodium (MELDNa) have been widely used to prioritize patients on the waiting list for liver transplantation resulting in a significant decrease in waiting list mortality/removal. Recent concern has been raised regarding the prognostic accuracy of MELD and MELDNa due, in part, to changes in recipients' profile such as body mass index, comorbidities, and general condition, including nutritional status and cause of liver disease, among others. This review aims to provide a comprehensive view of the current state of MELD and MELDNa advantages and limitations and promising alternatives. Finally, it will explore future options to increase the donor pool and improve donor-recipient matching.

Mortality and Causes of Death After Liver Transplantation: Analysis of Sex Differences in a Large Nationwide Cohort

In the last few years, several studies have analyzed sex and gender differences in liver transplantation (LT), but none have performed a disaggregated analysis of both mortality and causes of death. Data from 15,998 patients, 11,914 (74.5%) males and 4,069 (25.5%) females, transplanted between 2000 and 2016 were obtained from the Liver Transplantation Spanish Registry. Survival analysis was applied to explore recipient sex as a risk factor for death. The causes of death at different follow-up duration were disaggregated by recipient sex for analysis. Short-term survival was higher in males, whereas long-term survival was higher in females. Survival at 1, 5 and 10 years post-transplant was 87.43%, 73.83%, and 61.23%, respectively, in males and 86.28%, 74.19%, and 65.10%, respectively, in females (p = 0.05). Post-LT mortality related to previous liver disease also presented sex differences. Males had 37% increased overall mortality from acute liver failure (p = 0.035) and 37% from HCV-negative cirrhosis (p < 0.001). Females had approximately 16% increased mortality when the liver disease was HCV-positive cirrhosis (p = 0.003). Regarding causes of death, non-malignancy HCV+ recurrence (6.3% vs. 3.9% of patients; p < 0.001), was more frequently reported in females. By contrast, death because of malignancy recurrence (3.9% vs. 2.2% of patients; p = 0.003) and de novo malignancy (4.8% vs. 2.5% of patients; p < 0.001) were significantly more frequent in male recipients. Cardiovascular disease, renal failure, and surgical complications were similar in both. In summary, male patients have lower short-term mortality than females but higher long-term and overall mortality. In addition, the post-LT mortality risk related to previous liver disease and the causes of mortality differ between males and females.

Investigating for bias in healthcare algorithms: a sex-stratified analysis of supervised machine learning models in liver disease prediction

OBJECTIVES

The Indian Liver Patient Dataset (ILPD) is used extensively to create algorithms that predict liver disease. Given the existing research describing demographic inequities in liver disease diagnosis and management, these algorithms require scrutiny for potential biases. We address this overlooked issue by investigating ILPD models for sex bias.

METHODS

Following our literature review of ILPD papers, the models reported in existing studies are recreated and then interrogated for bias. We define four experiments, training on sex-unbalanced/balanced data, with and without feature selection. We build random forests (RFs), support vector machines (SVMs), Gaussian Naïve Bayes and logistic regression (LR) classifiers, running experiments 100 times, reporting average results with SD.

RESULTS

We reproduce published models achieving accuracies of >70% (LR 71.31% (2.37 SD) - SVM 79.40% (2.50 SD)) and demonstrate a previously unobserved performance disparity. Across all classifiers females suffer from a higher false negative rate (FNR). Presently, RF and LR classifiers are reported as the most effective models, yet in our experiments they demonstrate the greatest FNR disparity (RF; -21.02%; LR; -24.07%).

DISCUSSION

We demonstrate a sex disparity that exists in published ILPD classifiers. In practice, the higher FNR for females would manifest as increased rates of missed diagnosis for female patients and a consequent lack of appropriate care. Our study demonstrates that evaluating biases in the initial stages of machine learning can provide insights into inequalities in current clinical practice, reveal pathophysiological differences between the male and females, and can mitigate the digitisation of inequalities into algorithmic systems.

CONCLUSION

Our findings are important to medical data scientists, clinicians and policy-makers involved in the implementation medical artificial intelligence systems. An awareness of the potential biases of these systems is essential in preventing the digital exacerbation of healthcare inequalities.

A scoping review of inequities in access to organ transplant in the United States

Background

Organ transplant is the preferred treatment for end-stage organ disease, yet the majority of patients with end-stage organ disease are never placed on the transplant waiting list. Limited access to the transplant waiting list combined with the scarcity of the organ pool result in over 100,000 deaths annually in the United States. Patients face unique barriers to referral and acceptance for organ transplant based on social determinants of health, and patients from disenfranchised groups suffer from disproportionately lower rates of transplantation. Our objective was to review the literature describing disparities in access to organ transplantation based on social determinants of health to integrate the existing knowledge and guide future research.

Methods

We conducted a scoping review of the literature reporting disparities in access to heart, lung, liver, pancreas and kidney transplantation based on social determinants of health (race, income, education, geography, insurance status, health literacy and engagement). Included studies were categorized based on steps along the transplant care continuum: referral for transplant, transplant evaluation and selection, living donor identification/evaluation, and waitlist outcomes.

Results

Our search generated 16,643 studies, of which 227 were included in our final review. Of these, 34 focused on disparities in referral for transplantation among patients with chronic organ disease, 82 on transplant selection processes, 50 on living donors, and 61 on waitlist management. In total, 15 studies involved the thoracic organs (heart, lung), 209 involved the abdominal organs (kidney, liver, pancreas), and three involved multiple organs. Racial and ethnic minorities, women, and patients in lower socioeconomic status groups were less likely to be referred, evaluated, and added to the waiting list for organ transplant. The quality of the data describing these disparities across the transplant literature was variable and overwhelmingly focused on kidney transplant.

Conclusions

This review contextualizes the quality of the data, identifies seminal work by organ, and reports gaps in the literature where future research on disparities in organ transplantation should focus. Future work should investigate the association of social determinants of health with access to the organ transplant waiting list, with a focus on prospective analyses that assess interventions to improve health equity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12939-021-01616-x.

Graft Survival and Segment Discards Among Split-Liver and Reduced-Size Transplantations in the United States From 2008 to 2018

Split-liver transplantation has allocation advantages over reduced-size transplantation because of its ability to benefit 2 recipients. However, prioritization of split-liver transplantation relies on the following 3 major assumptions that have never been tested in the United States: similar long-term transplant recipient outcomes, lower incidence of segment discard among split-liver procurements, and discard of segments among reduced-size procurements that would be otherwise "transplantable." We used United Network for Organ Sharing Standard Transplant Analysis and Research data to identify all split-liver (n = 1831) and reduced-size (n = 578) transplantation episodes in the United States between 2008 and 2018. Multivariable Cox proportional hazards modeling was used to compare 7-year all-cause graft loss between cohorts. Secondary analyses included etiology of 30-day all-cause graft loss events as well as the incidence and anatomy of discarded segments. We found no difference in 7-year all-cause graft loss (adjusted hazard ratio [aHR], 1.1; 95% confidence interval [CI], 0.8-1.5) or 30-day all-cause graft loss (aHR, 1.1; 95% CI, 0.7-1.8) between split-liver and reduced-size cohorts. Vascular thrombosis was the most common etiology of 30-day all-cause graft loss for both cohorts (56.4% versus 61.8% of 30-day graft losses; P = 0.85). Finally, reduced-size transplantation was associated with a significantly higher incidence of segment discard (50.0% versus 8.7%) that were overwhelmingly right-sided liver segments (93.6% versus 30.3%). Our results support the prioritization of split-liver over reduced-size transplantation whenever technically feasible.

Are Hepatitis C Positive Female Liver Transplant Recipients Still at Increased Risk for Graft Failure? Reexamining the Disparity in the Modern Era of Direct-acting Antiviral Agents

BACKGROUND

This study aimed to compare the outcomes of hepatitis C virus (HCV) positive (+) female liver transplant recipients to HCV negative (-) female and HCV+ male recipients before and after the direct-acting-antiviral (DAA) era.

METHODS

The United Network for Organ Sharing liver transplant database was retrospectively reviewed from 2002 to 2017. The DAA era was defined as ≥2014.

RESULTS

In the pre-DAA era, HCV+ female recipients had greater risk for graft failure compared with HCV+ male (hazard ratio [HR], 1.06; 95% confidence interval [CI], 1.01-1.11; P = 0.03) and HCV- female (HR, 1.51; 95% CI, 1.43-1.60; P < 0.001) recipients. In the post-DAA era, HCV+ female recipients had lower risk for graft failure compared with HCV+ male recipients (HR, 0.82; 95% CI, 0.70-0.97; P = 0.02) and equivalent outcomes to HCV- female recipients. HCV+ female recipients with graft failure had increased likelihood of graft failure due to disease recurrence compared with HCV+ male recipients in the pre-DAA era (odds ratio, 1.23; 95% CI, 1.08-1.39; P = 0.001) but not in the post-DAA era.

CONCLUSIONS

Although historically HCV+ female recipients were at disproportionately increased risk for graft failure and disease recurrence, this disparity has been eliminated in the DAA era.

Epidemiology and Prognostic Significance of Rapid Response System Activation in Patients Undergoing Liver Transplantation

Patients undergoing liver transplantation have a high risk of perioperative clinical deterioration. The Rapid Response System is an intensive care unit-based approach for the early recognition and management of hospitalized patients identified as high-risk for clinical deterioration by a medical emergency team (MET). The etiology and prognostic significance of clinical deterioration events is poorly understood in liver transplant patients. We conducted a cohort study of 381 consecutive adult liver transplant recipients from a prospectively collected transplant database (2011–2017). Medical records identified patients who received MET activation pre- and post-transplantation. MET activation was recorded in 131 (34%) patients, with 266 MET activations in total. The commonest triggers for MET activation were tachypnea and hypotension pre-transplantation, and tachycardia post-transplantation. In multivariable analysis, female sex, increasing Model for End-Stage Liver Disease score and hepatorenal syndrome were independently associated with MET activation. The unplanned intensive care unit admission rate following MET activation was 24.1%. Inpatient mortality was 4.2% and did not differ by MET activation status; however, patients requiring MET activation had significantly longer intensive care unit and hospital length of stay and were more likely to require inpatient rehabilitation. In conclusion, liver transplant patients with perioperative complications requiring MET activation represent a high-risk group with increased morbidity and length of stay.

Gender disparities in transplantation

PURPOSE OF REVIEW

Transplantation is the life-saving therapy for patients suffering from end-organ failure, and as such, equitable access to transplantation (ATT) is of paramount importance. Unfortunately, gender/sex-based disparities exist, and despite the transplant community's awareness of this injustice, gender/sex-based disparities have persisted for more than two decades. Importantly, no legislation or allocation policy has addressed inequity in ATT that women disproportionately face. In fact, introduction of the model for end-stage liver disease-based liver allocation system in 2002 widened the gender disparity gap and it continues to be in effect today. Moreover, women suffering from kidney disease are consistently less likely to be referred for transplant evaluation and subsequently less likely to achieve a kidney transplant, yet they comprise the majority of living kidney donors.

RECENT FINDINGS

Acknowledging gender/sex-based disparities in ATT is the first step toward interventions aimed at mitigating this long-standing injustice in healthcare.

SUMMARY

This article provides a background of end-stage liver and kidney disease in women, summarizes the existing literature describing the issue of gender disparity in ATT, and identifies potential areas of intervention and future investigation.

Changing trends in liver transplantation indications in Saudi Arabia: from hepatitis C virus infection to nonalcoholic fatty liver disease

Background

Several trend analyses on liver transplantation (LT) indications have been published in the U.S. and in other countries, but there are limited data on LT indication trends in Saudi Arabia (SA), especially since the availability of direct-acting antivirals (DAAs) treatment for hepatitis C virus (HCV). This study aimed to analyze trends in the frequency of LT indications among LT recipients in SA over a 19-year period and examine associations between etiologic-specific trends and clinicodemographic characteristics.

Methods

This retrospective study analyzed clinical and surgical data of adult patients (n = 1009) who underwent LT at the King Faisal Specialist Hospital & Research Center (Riyadh, SA) between 2001 and 2019. Spearman’s rank correlation, Poisson regression, and Joinpoint regression analysis were employed to assess changes in LT etiologic trends.

Results

In the first period (2001–2010), the main LT indications were HCV (41.9%) and hepatitis B virus (HBV) (21.1%), but nonalcoholic steatohepatitis (NASH) (29.7%) surpassed HCV (23.7%) as the leading LT indication in the second period (2011–2019); and the trends were significant in correlation analyses [incidence rate ratio (IRR) = 1.09 (1.06–1.13) for NASH; IRR = 0.93 (0.91–0.95) for HCV]. In the Joinpoint regression analysis, increases in NASH from 2006 to 2012 (+ 32.1%) were statistically significant, as were the decreases in HCV from 2004 to 2007 (− 19.6%) and from 2010 to 2019 (− 12.1%). Similar patterns were observed in LT etiological comparisons before and after the availability of DAAs and within hepatocellular carcinoma stratifications.

Conclusions

Trends in the epidemiology of LT indications among LT recipients in SA have changed over a 19-year period. Most notably, NASH has eclipsed HCV in the country due to the effective treatment strategies for HCV. These trends in NASH now need an aggressive public health response to minimize and avert future onset of additional clinical and economic strains on health care systems and LT centers in SA.

Racial, Gender, and Socioeconomic Disparities in Liver Transplantation

Liver transplantation (LT) is a life-saving therapy; therefore, equitable distribution of this scarce resource is of paramount importance. We searched contemporary literature on racial, gender, and socioeconomic disparities across the LT care cascade in referral, waitlist practices, allocation, and post-LT care. We subsequently identified gaps in the literature and future research priorities. Studies found that racial and ethnic minorities (Black and Hispanic patients) have lower rates of LT referral, more advanced liver disease and hepatocellular carcinoma at diagnosis, and are less likely to undergo living donor LT (LDLT). Gender-based disparities were observed in waitlist mortality and LT allocation. Women have lower LT rates after waitlisting, with size mismatch accounting for much of the disparity. Medicaid insurance has been associated with higher rates of chronic liver disease and poor waitlist outcomes. After LT, some studies found lower overall survival among Black compared with White recipients. Studies have also shown lower literacy and limited educational attainment were associated with increased posttransplant complications and lower use of digital technology. However, there are notable gaps in the literature on disparities in LT. Detailed population-based estimates of the advanced liver disease burden and LT referral and evaluation practices, including for LDLT, are lacking. Similarly, little is known about LT disparities worldwide. Evidence-based strategies to improve access to care and reduce disparities have not been comprehensively identified. Prospective registries and alternative "real-world" databases can provide more detailed information on disease burden and clinical practices. Modeling and simulation studies can identify ways to reduce gender disparities attributed to size or inaccurate estimation of renal function. Mixed-methods studies and clinical trials should be conducted to reduce care disparities across the transplant continuum.

COVID-19 and liver disease: mechanistic and clinical perspectives

Our understanding of the hepatic consequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and its resultant coronavirus disease 2019 (COVID-19) has evolved rapidly since the onset of the pandemic. In this Review, we discuss the hepatotropism of SARS-CoV-2, including the differential expression of viral receptors on liver cell types, and we describe the liver histology features present in patients with COVID-19. We also provide an overview of the pattern and relevance of abnormal liver biochemistry during COVID-19 and present the possible underlying direct and indirect mechanisms for liver injury. Furthermore, large international cohorts have been able to characterize the disease course of COVID-19 in patients with pre-existing chronic liver disease. Patients with cirrhosis have particularly high rates of hepatic decompensation and death following SARS-CoV-2 infection and we outline hypotheses to explain these findings, including the possible role of cirrhosis-associated immune dysfunction. This finding contrasts with outcome data in pharmacologically immunosuppressed patients after liver transplantation who seem to have comparatively better outcomes from COVID-19 than those with advanced liver disease. Finally, we discuss the approach to SARS-CoV-2 vaccination in patients with cirrhosis and after liver transplantation and predict how changes in social behaviours and clinical care pathways during the pandemic might lead to increased liver disease incidence and severity.

Racial and Sex Disparities in Hepatocellular Carcinoma in the USA

PURPOSE OF REVIEW

In this review, we aim to provide a summary of the current literature on race and gender disparities in hepatocellular carcinoma (HCC) incidence, stage at diagnosis, treatment and prognosis in the United States.

RECENT FINDINGS

HCC incidence rates are rising in the U.S. in all racial/ethnic groups except for Asian/Pacific Islanders, with disproportionate rises and the highest rates among Hispanics compared to Blacks and non-Hispanic whites. There are striking sex disparities in HCC incidence and mortality; however, with the shifting epidemiology of HCC risk factors in the U.S, there is recent evidence that HCC is trending towards less male predominance, particularly among younger birth cohorts. Despite significant advances in HCC treatment over the past decade, disparities in HCC surveillance and treatment receipt persist among racial and ethnic minorities and the socioeconomically disadvantaged. Black patients continue to experience worse survival outcomes than non-Black patients with HCC.

SUMMARY

There are significant racial and gender disparities in HCC incidence, treatment, and mortality in the U.S. Though these disparities are well-documented, data are still limited on the specific determinants driving disparities in HCC. To achieve health equity for all patients with HCC, we must advance beyond simply reporting on disparities and begin implementing targeted interventions to eliminate disparities.

Liver-related mortality is similar among men and women with cirrhosis

BACKGROUND & AIMS

Sex-based differences are known to significantly contribute to outcomes in patients with chronic liver diseases; however, the role of patient sex in cirrhosis is unclear. We aimed to study the relationship between patient sex and cirrhosis.

METHODS

We analyzed a cohort of 20,045 patients with cirrhosis using a Chicago-wide electronic health record database that was linked with the United Network for Organ Sharing and cause of death data from the state death registry. Adjusted Cox survival analyses and competing risk analyses were performed to obtain subdistribution hazard ratios (HRs) for liver-related cause of death.

RESULTS

Female and male patients had similar age, racial distribution, insurance status, and comorbidity status by Elixhauser score. Females had higher rates of cholestatic liver disease (17.1% vs. 6.2%, p <0.001) and non-alcoholic steatohepatitis (29.8% vs. 21.2%, p <0.001) than males. They were less likely to have portal hypertensive complications and had lower peak MELD-Na scores during follow-up. Female sex was associated with a decreased hazard of all-cause mortality (adjusted HR 0.85; 95% CI 0.80-0.90). This effect was attenuated when liver-related mortality was examined (subdistribution HR 0.93; 95% CI 0.87-1.00). No significant difference was noted for women who were 'ever-listed' in competing risk analyses for either all-cause mortality (subdistribution HR 1.09; 95% CI 0.88-1.35) or liver-related death (subdistribution HR 1.12; 95% CI 0.87-1.43), despite lower rates of listing (7.5% vs. 9.8%; p <0.001) and transplant (3.5% vs. 5.2%; p <0.001).

CONCLUSIONS

In this longitudinal study of patients with cirrhosis, female sex was associated with a survival advantage likely driven by lower rates of non-liver-related death. Women were not at an increased risk of liver-related death despite lower rates of listing and transplantation.

LAY SUMMARY

Patient sex is an important contributor in many chronic diseases, including cirrhosis. Prior studies have suggested that female sex is associated with worse outcomes. We analyzed a cohort of 20,045 patients with cirrhosis using a Chicago-wide electronic health record database. Using multivariate competing risk analyses, we found that female sex in cirrhosis is actually associated with a lower risk of all-cause mortality and has no association with liver-related mortality. Our findings are novel because we show that women with cirrhosis have a similar risk of liver-related death as their male counterparts, despite lower rates of listing and transplantation.

Sex disparities in presentation and prognosis of 1110 patients with hepatocellular carcinoma

BACKGROUND

Although sex disparities in hepatocellular carcinoma (HCC) incidence have been well described, there are limited data examining sex disparities in HCC prognosis.

AIM

To characterise sex differences in HCC presentation and prognosis.

METHODS

We performed a retrospective study of consecutive patients (n = 1110, 23.5% women) diagnosed with HCC between 2008 and 2017 at two US health systems. We used Cox proportional hazard and multivariable logistic regression models to identify factors associated with overall survival, early tumour detection and response to HCC treatment (per the modified Response Evaluation Criteria in Solid Tumors [mRECIST] criteria).

RESULTS

Women were older at HCC diagnosis (mean 62.5 vs 59.2 years, P < 0.001) and had a higher proportion of early-stage tumours (53.1% vs 43.7% Barcelona Clinic Liver Cancer [BCLC] stage 0/A, P = 0.04), but similar liver function compared to men (49.2% vs 47.1% Child Pugh A, P = 0.27). In univariable analysis, women had significantly better overall survival than men (median 17.1 vs 12.0 months, P = 0.02). When stratified by age, younger (<65 years) women had better overall survival than men (18.3 vs 11.2 months, P = 0.02); however, older (≥65 years) women and men had similar overall survival (15.5 vs 15.7 months, P = 0.45). In multivariable analysis, female sex was independently associated with lower mortality after adjusting for age, race/ethnicity, alpha-fetoprotein, BCLC stage, Albumin-Bilirubin grade and Child Pugh score (hazard ratio [HR] 0.82, 95% confidence interval [CI] 0.68-0.98). In secondary analyses, female sex was independently associated with early tumour detection (odds ratio [OR] 1.46, 95% CI 1.05-2.02) and response to first HCC treatment (OR 1.72, 95% CI 1.18-2.53) after adjusting for the same covariates.

CONCLUSION

In a large cohort of patients with HCC, women had significantly better prognosis than men.

Influence of donor and recipient gender on liver transplantation outcomes in Europe

BACKGROUND & AIMS

The impact of gender and donor/recipient gender mismatch on LT outcomes is controversial. The aim of this study was to compare outcomes of LT in Europe, using the ELTR database, between male and female recipients, including donor/recipient gender mismatch.

METHODS

Recipient, donor and transplant characteristics were compared between male and female patients. Patient survival was compared between groups, and the impact of donor/recipient gender matching as well as donor and recipient anthropometric characteristics were evaluated as potential risk factors for post-LT death/graft loss.

RESULTS

A total of 46,334 LT patients were evaluated (70.5% men and 29.5% women). Ten-year survival rate was significantly higher in female than in male recipients (66% vs 59%, P < .0001). At multivariate analysis, adjusted for indication to LT and type of graft, donor/recipient gender mismatch (HR 1.12, 95% CI 1.04-1.2; P = .003), donor age > 60 years (HR 1.09, 95% CI 1.01-1.18; P = .027) and recipient age (HR 1.02, 95% CI 1.1-1.02; P < .0001) were significantly associated with post-LT lower survival rate in men. Conversely in female recipients, donor BMI > 30 (HR 1.32, 95% CI 1.09-1.6; P = .005), donor age > 60 years (HR 1.15, 95% CI 1.01-1.32; P = .027) and recipient age (HR 1.02, 95% CI 1.01-1.02; P < .0001) were significantly associated with lower post-LT survival rate.

CONCLUSIONS

Donor/recipient gender mismatch in male recipients and the use of obese donor in female recipients are associated with reduced survival after LT. Therefore, the incorporation of donor and recipient anthropometric quantities in the allocation process should be a matter of further studies, as their matching can significantly influence long-term outcomes.

Women who undergo liver transplant have longer length of stay post-transplant compared with men

BACKGROUND

Women on the liver transplant waitlist are at greater risk of hospitalization compared with men, but whether this impacts length of stay (LOS) post-transplant is unknown. We aimed to evaluate gender disparities in post-transplant LOS, an important surrogate of health resource utilization post-transplant.

METHODS

Using the UNOS/OPTN registry, we analysed all non-Status 1 adult deceased donor liver transplant recipients without exception points from 2008 to 2017. Poisson regression associated female gender with post-transplant LOS.

RESULTS

Of 27 294 transplant recipients, 36% were women. Women were more likely to be hospitalized pretransplant than men (44% vs 39%, P < .01). Post-transplant, women were more likely to have prolonged (≥20d) LOS (25% vs 22%, P < .01). In univariable analysis, female gender was associated with longer post-transplant LOS (IRR 1.09, 95%CI 1.06-1.12, P < .01). Prolonged pretransplant admission was also associated with post-transplant LOS (IRR 1.83, 95%CI 1.77-1.89, P < .01). In multivariable analysis, female gender remained independently associated with post-transplant LOS (aIRR 1.05, 95%CI 1.02-1.08, P < .01), after adjustment for age, UNOS region, insurance type, MELDNa, cirrhosis complications, and donor risk index. Pretransplant hospitalization mediated this relationship, explaining 14.1% (95%CI 9.7%-25.4%) of the total effect.

CONCLUSIONS

Women who undergo deceased donor liver transplant have increased healthcare utilization in the peritransplant period compared with men. Reducing gender disparities in liver transplantation, including the disproportionate burden of healthcare utilization by women pre- and post-transplant, will require interventions targeted at preventing hospitalization among women on the transplant waitlist and developing tools aimed at better characterizing the severity of end-stage liver disease in women.

Sex and Gender Disparities in Pretransplant Characteristics and Relationships with Postoperative Outcomes in Liver Transplant Recipients with Alcoholic Liver Disease

OBJECTIVES

Previous studies of liver transplant recipients have reported discrepancies with regard to gender and/or sex differences but have focused on pretransplant outcomes. Female candidates are less likely to receive liver transplant and more likely to die or be delisted than their male counterparts. Here, we examined differences in men versus women with alcoholic liver disease before liver transplant and the effects of these differences on posttransplant survival.

MATERIALS AND METHODS

We analyzed the Scientific Registry of Transplant Recipients records of adult, deceased-donor, whole liver transplant recipients with decompensated alcoholic liver disease from 2002 to 2017 to evaluate the effects of gender on survival in 2 alcoholic liver disease cohorts: (a) including and (b) excluding recipients with additional diagnoses. Pretransplant characteristics were compared using chi-square or t tests. Kaplan-Meier and multivariable proportional hazards regression models were used to evaluate the main and covariable-adjusted effects of gender on survival.

RESULTS

Of 13781 transplant recipients with decompensated end-stage liver disease, as defined by Model for End-Stage Liver Disease score ≥ 15, 10924 (79%) were men and 2857 (21%) were women. Women had higher Model for End-Stage Liver Disease scores, higher rates of stage 4 and 5 chronic kidney disease, and were more likely to be on dialysis or ventilator support at time of transplant (all P < .05). Among all recipients, and after adjusting for risk factors, men were approximately 9% more likely than women to experience long-term graft loss (hazard ratio = 1.093; 95% confidence interval, 1.00-1.19; P = .043). However, sex difference was not associated with risk of graft loss among those without additional diagnoses (hazard ratio = 1.09; 95% confidence interval, 0.99-1.21; P = .095).

CONCLUSIONS

Although women with alcoholic liver disease who undergo liver transplant have higher severity of illness than their male counterparts, long-term outcomes are comparable.