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

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.

Common definitions and variables are needed for the United States to join the conversation on acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is a variably defined syndrome characterized by acute decompensation of cirrhosis with organ failures. At least 13 different definitions and diagnostic criteria for ACLF have been proposed, and there is increasing recognition that patients with ACLF may face disadvantages in the current United States liver allocation system. There is a need, therefore, for more standardized data collection and consensus to improve study design and outcome assessment in ACLF. In this article, we discuss the current landscape of transplantation for patients with ACLF, strategies to optimize organ utility, and data opportunities based on emerging technologies to facilitate improved data collection.

Evolving trends and outcomes on the US liver transplant waitlist of alcohol-associated hepatitis patients with very high MELD scores

Liver transplantation (LT) in patients with alcohol-associated hepatitis (AH) has rapidly increased following the coronavirus disease 2019 pandemic and the implementation of the Acuity Circle policy, raising questions of equity and utility. Waitlist mortality among high (≥37) Model for End-Stage Liver Disease LT candidates with AH and post-transplant survival were assessed with a semiparametric survival regression and a generalized linear mixed-effect model with LT centre- and listing date-level random intercepts. These models demonstrate a lower mortality for the candidates listed with AH (adjusted sub-hazard ratio .58_.72_.90 and odds ratio .44_.66_.99) when compared to other diagnoses (autoimmune hepatitis, metabolic dysfunction-associated fatty liver disease and primary biliary cholangitis). Post-LT survival was comparable. This study highlights the limitations of current tools in characterizing the risk of mortality, and thus need for the modifications in prioritizing LT candidates with AH. Policy revision may be needed to ensure equivalent access to LT regardless of diagnosis.

Impact of Recipient Age at Liver Transplant on Long-term Outcomes

BACKGROUND

The age of a liver transplant (LT) candidate is one of many variables used in the transplant selection process. Most research about the age at transplant has used prespecified age ranges or categories in assessing associations with transplant outcomes. However, there is a lack of knowledge about the age at transplant and survival. This study aimed to examine associations of age at transplant as a continuous variable, in conjunction with other patient and disease-related factors, with patient and graft survival after LT.

METHODS

We used the Standard Transplant Analysis and Research data to identify LT recipients between January 2002 and June 2018. Cox regression models with a restricted cubic spline term for age examined associations with graft and patient survival after LT. We assessed the interactions of age with recipients' sex, race/ethnicity, region, indication for transplant, body mass index, model for end-stage liver disease score, diabetes, functional status at transplant, and donor risk index.

RESULTS

Age at the time of LT showed a nonlinear association with both graft and patient survival. Each demographic, clinical, transplant-related, and donor-related factor influenced these relationships differently.

CONCLUSIONS

Our results suggest that some older LT candidates may be better than some younger candidates and that clinicians should not exclusively use age to determine who receives LT.