Liver transplantation (LT) is the standard therapy for end-stage liver disease; however, organ availability continues to limit access worldwide.^(1,2) To mitigate this shortage, LT programs have progressively broadened donor acceptance, increasingly relying on grafts that fall outside traditional "standard" profiles, commonly referred to as extended criteria donor (ECD) organs. Extended criteria donor status is assigned when donor characteristics associated with poorer graft performance are present, including higher rates of early allograft dysfunction and primary non-function.^(3,4) Despite the potential for increased perioperative risk, ECD grafts have become integral to contemporary LT activity.⁽⁵⁾

Extended criteria donor grafts are commonly used across allocation systems. In Brazil, Eurotransplant-based definitions have identified ECD criteria in a large proportion of donor offers,⁽⁶⁾ with similarly high rates reported in Eurotransplant member countries, North America, and other cohorts using comparable or alternative definitions.^(7-13) This widespread reliance underscores the need for structured approaches to quantify and manage the risk when marginal grafts are used.

As use of ECD increases, transplant teams require practical tools to support donor-recipient matching and anticipate post-transplant outcomes. Multiple prognostic models have been proposed to inform acceptance and matching decisions, particularly when donor risk features are present.^(14-16) The Balance of Risk (BAR) score may outperform commonly used alternatives such as the Model for End-Stage Liver Disease (MELD), Donor-MELD (D-MELD), and the Donor Risk Index (DRI) in predicting post-LT outcomes.⁽¹⁶⁾ By integrating donor and recipient variables into a single composite estimate, the BAR may be especially useful when evaluating higher-risk scenarios, including transplants performed with ECD grafts.⁽¹⁶⁾

Accordingly, we aimed to assess post-liver transplantation patient and graft survival by Eurotransplant-defined extended criteria donor status and evaluate whether BAR, D-MELD, and DRI can discriminate mortality and graft loss in this cohort.

This study has two principal findings. First, the use of grafts meeting the Eurotransplant ECD definitions was not independently associated with inferior long-term survival in this cohort. Second, among the evaluated prognostic models, only the BAR score consistently demonstrated significant associations with mortality and graft loss, supporting its clinical utility as an integrated risk assessment tool for LT.

The absence of a significant survival disadvantage among ECD recipients reinforces the concept that donor marginality, when considered in isolation, may not fully determine post-transplant outcomes. The adoption of ECD grafts is a widely used response to persistent organ scarcity.⁽¹⁷⁾ As transplant programs increasingly accept donors with expanded criteria, the clinical question shifts from whether ECD grafts should be used to how their risks can be quantified and balanced appropriately. Our findings suggest that structured donor-recipient matching may mitigate the adverse effects traditionally attributed to ECD classification alone.

Despite frequent ECD use, the overall survival in our cohort was in line with the outcomes reported by high-volume programs,⁽¹⁸⁾ despite the substantial proportion of ECD graft utilization. This observation highlights that outcomes depend on a multifactorial interplay involving donor features, recipient severity, ischemia time, and perioperative management. Therefore, the binary categorization of grafts as ECD or non-ECD may oversimplify a complex biological and clinical reality.

The high prevalence of ECD use at our center mirrors national and international patterns. In Brazil, analyses applying Eurotransplant-based criteria have demonstrated ECD rates approaching 78%.⁽⁶⁾ Other Brazilian studies have similarly documented extensive reliance on ECDs, although with heterogeneous definitions.^(12,13,19) These data confirm that ECD transplantation is firmly integrated into routine practice rather than being an exceptional strategy. Consequently, robust tools to support decision-making are essential to ensure that the expanded utilization does not compromise acceptable outcomes.

International registry analyses further contextualized these findings. A large retrospective evaluation of the OPTN/UNOS database from 2001 to 2020 demonstrated significant improvement in graft survival among ECD recipients over time, with more recent ECD cohorts achieving outcomes that compared favorably to earlier non-ECD eras.⁽²⁰⁾ Similarly, a study combining data from the German Transplant Registry and the United States Scientific Registry of Transplant Recipients (SRTR), encompassing over 90,000 donors and more than 70,000 adult transplants, reported that most Eurotransplant-defined ECD criteria were not independently associated with reduced short-term survival, except for donor age.⁽²¹⁾ These findings suggest that the prognostic impact of ECD characteristics is dynamic and influenced by evolving clinical expertise and allocation practices.

In this context, the performance of prognostic models is central. In our study, the BAR score was the only evaluated index significantly associated with mortality and graft loss, regardless of whether it was analyzed categorically or as a continuous variable. Each one-point increment in the BAR was associated with a 7.3% increase in mortality risk and a 17.4% increase in graft loss risk. In contrast, D-MELD and DRI were not significantly associated with outcomes in this cohort. These results underscore the potential advantages of composite scores that integrate donor and recipient variables, rather than focusing predominantly on a single domain.

The superiority of BAR over MELD-based or donor-focused indices has been previously suggested.⁽¹⁶⁾ A Brazilian retrospective study including 402 liver transplant recipients between 1997 and 2012 reported significantly lower 1-year survival among patients with BAR ≥11 compared to those with lower scores (44% versus 69%, p=0.001), although long-term predictive performance was considered limited.⁽²²⁾ Our findings extend this evidence by demonstrating consistent associations between BAR and both mortality and graft loss in a contemporary cohort with follow-up extending to 5 years using internationally standardized ECD criteria.

Organ utilization and discard patterns provide an additional layer of interpretation. Brazilian data indicate that each additional ECD criterion increases the likelihood of organ refusal, with one analysis showing a 64.4% rise in refusal probability per added risk factor.⁽⁶⁾ Moreover, evaluations of graft discard in high-volume centers have revealed that many livers are declined due to perceived graft-related abnormalities.⁽¹⁹⁾ These patterns highlight the potential disconnect between risk perception and actual post-transplant performance. In this scenario, validated composite scores may help support more objective and reproducible decision-making during organ assessment.

This study had certain limitations. The retrospective and single-center design may restrict generalizability. Although the cohort included 414 transplants, it may not reflect the full heterogeneity of the national practice. Donor BMI was derived from estimated rather than directly measured weight, potentially introducing imprecision, and hepatic steatosis was assessed macroscopically rather than histologically. Additionally, allocation policies, regional donor availability, and healthcare disparities may have influenced the outcomes but were not directly modeled.

Despite these limitations, this study contributes relevant data to the discussion on ECD utilization and prognostic modeling after LT. By applying internationally recognized ECD definitions and directly comparing commonly used severity scores, we demonstrated that composite donor-recipient risk stratification, particularly using the BAR score, may provide a more nuanced and clinically useful framework than reliance on ECD classification alone.

Grafts meeting Eurotransplant extended criteria definitions were not independently associated with inferior patient or graft survival in this cohort, suggesting that donor classification alone may not adequately determine post-transplant prognosis. Our findings indicate that integrated donor-recipient risk assessment provides a more informative framework for clinical decision-making, with the BAR score demonstrating consistent associations with both mortality and graft loss. These results support the incorporation of composite severity models into allocation and acceptance strategies to optimize graft utilization while maintaining favorable long-term outcomes.