Donation after circulatory death (DCD) donors have traditionally been considered “marginal” liver donors. Historically, concerns over ischemia–reperfusion injury, biliary complications, early allograft dysfunction, and long-term outcomes have limited utilization of livers from DCD donors, and particularly from older donors. Recent advances in donor management, recovery technique, and especially machine perfusion have helped mitigate these challenges. As utilization of livers from these donors has increased, there is growing interest in understanding which DCD livers can be used with acceptable outcomes and which recipients are best suited for these grafts. In this issue of Transplantation, Nakayama et al leveraged national registry data from the United States to study the outcomes of 29 327 adult liver transplant candidates who were offered a liver from an older DCD donor between October 2016 and June 2024.1 The authors compared the outcomes of 704 candidates for whom an older DCD offer was accepted to 29 074 candidates for whom the offer was declined. Candidates were followed for 3 y post-decision. For candidates for whom an older DCD offer was declined, only 53.8% had received a transplant after 3 y, whereas 15.1% had died and another 19.7% were removed from the waitlist for other reasons. After matching on model for end-stage liver disease (MELD) score to ensure comparability, this translated to an absolute three-year survival of 86.6% among those who accepted compared with 74.9% among those who declined. On average, accepting an older DCD offer was associated with a 54% lower risk of mortality than declining that offer (even if the candidate subsequently received another transplant). However, this survival benefit varied by candidate age and allocation MELD at offer. Candidates 50–59 y old and 60+ y old had a 65% and 56% lower risk of mortality when accepting an older DCD offer, whereas candidates <50 y old had no survival benefit at all. Similarly, candidates with a MELD 25–40 and 15–24 at the time of offer had a 69% and 65% lower risk of mortality when accepting an older DCD offer, whereas candidates with a MELD 6–14 had no survival benefit at all. This large registry-based study from the United States provides compelling empirical support for the utilization of older DCD livers for transplantation, particularly for candidates 50+ y old and with a MELD ≥15. It extends prior work showing a survival benefit with accepting any DCD liver to the higher-risk population of DCD donors 60+ y old.2,3 This is an important set of donors to focus on as the growing use of machine perfusion has facilitated a rapid expansion of the donor pool, particularly for DCD donors.4 In fact, the authors show data that supports this—utilization of older DCD donors increased from <100/y in 2016–2022 to 210 transplants in 2023 and 334 transplants in 2024. The authors have also clearly shown that this increased utilization has not come at the expense of patient outcomes as accepting these grafts extends survival. Concerns over outcomes with older DCD donors have typically focused on inferior posttransplant outcomes compared with younger non-DCD donors, yet patients waiting for a liver transplant may focus less on whether their outcome could have been better with a younger non-DCD donor (an offer they may never receive) and more on whether the offer they have will extend their life. These findings also align with the European experience, where even 70+ y old DCD donors have been successfully utilized with excellent outcomes.5 Although machine perfusion has clearly facilitated the ability to use these grafts successfully, it is important to note that there is limited granularity about use of these techniques in US national registry data, and so it is challenging to characterize the comparative advantages of the variety of machine perfusion techniques that exist in this setting. Indeed, there is no clear evidence for the superiority of 1 technique over the other. Additionally, normothermic machine perfusion cases are only captured if placed on pump at the donor hospital, and so “back-to-base” cases are often not captured. Furthermore, the costs of using normothermic machine perfusion are nontrivial and may be prohibitive in some areas. Another limitation of US national registry data is that information about posttransplant outcomes such as biliary complications, ischemic cholangiopathy, or early allograft dysfunction are not available. The risks of these complications may be increased with older DCD livers and the perceived likelihood of these or their impact on a particular recipient may be 1 reason that these are declined. However, these outcomes are also important to patients and will need to be monitored as experience with using older DCD donors develops. There are also challenges in interpreting the results of this study that arise from the study design. First, this study only includes older DCD livers ultimately accepted for transplantation and does not include livers which were declined for everyone. Therefore, it is difficult to say the extent to which these results generalize to all older DCD livers, as the decision to accept or decline a given liver takes into account many factors other than age (eg, concomitant steatosis). It is possible that not every older DCD liver would be associated with a survival benefit, especially for those with other risk factors for worse outcomes. Additionally, age in this study was modeled as a binary exposure. Although helpful for clinical decision-making, dichotomizing a continuous variable is associated with information loss and an inability to explore non-linear effects, which could be relevant in this population. This study is a strong addition to the growing body of literature supporting the use of older DCD donors for liver transplantation. It demonstrates that for many candidates, particularly those who are older or with a higher MELD, the risks of declining an older DCD donor can exceed those of accepting it. These data can help facilitate increased utilization while mitigating concerns over inferior outcomes. Although more work is needed to understand how machine perfusion techniques can be used to further improve outcomes and utilization of older DCD donors, this study emphasizes that these donors can and should be used for well-selected candidates.
Jackson et al. (Thu,) studied this question.