LAUSR

In this issue of the journal, Bowring et al.(1) examine the impact of splitliver (SL) offer acceptance on liver transplant candidate mortality. SL transplantation was developed to increase access to sizeappropriate deceased donor liver allografts for young children who are at particularly high risk of waitlist mortality.(2,3) It is a technically challenging procedure in which a whole liver (WL) is meticulously divided into 2 transplantable partial allografts. The leftsided allograft is most often allocated to a child, whereas the larger rightsided allograft is commonly allocated to an adult. When successfully performed, SL transplantation doubles the number of liver transplantations performed from a single donor and helps mitigate the organ shortage. The techniques for implantation and complications associated with SL transplantation pose unique challenges compared with WL transplantation. In SL transplantation, a microvascular arterial reconstruction must be performed in the recipient of the graft allocated without the common hepatic artery. The need for a hilar dissection/ hepatic duct transection and the presence of a parenchymal cut surface increases the risk for biliary complications. In addition, the reduced liver mass of the SL requires more careful recipient selection to minimize the risk of early postoperative hepatic insufficiency (smallforsize syndrome) or primary graft nonfunction.(4) These challenges, in conjunction with historical data suggesting inferior graft survival, explain the overall hesitancy of many centers to use SL for adult recipients.(5,6) As a result, half of all adult SL offers are accepted below candidate sequence number 12, and SL comprise only 1.5% of all liver transplantations performed in the United States.(7) SL use is also concentrated at certain centers with expertise in the procedure, with only 10 centers performing nearly 50% of all SL transplants in the United States.(7) In their groundbreaking article, “Survival Benefit of SplitLiver Transplantation for Pediatric and Adult Candidates,” Bowring et al.(1) examine mortality in adult and pediatric candidates who accepted an SL offer compared with mortality in candidates who declined an SL offer and remained on the transplant waiting list. Their findings call into question the practice of declining an SL offer in the hope of finding a “better” offer in the future. The authors used a case control study design to analyze Scientific Registry of Transplant Recipients data on candidates who were ever offered an SL graft. The primary endpoint was mortality after adjustment for individual patient factors. The results demonstrated a 43% reduction in mortality for small pediatric candidates (≤7 kg) and a 63% reduction in mortality for adult candidates who accepted an SL offer compared with those who declined an SL offer. The authors conclude that the benefit of using the SL allograft greatly exceeds the combined risk of mortality from waiting for a different offer and posttransplant mortality from using a different allograft of unknown quality. Given these findings, it stands to reason that a concerted effort should be made to prioritize SL transplantation in the United States. However, current local and regional variances attempting to increase the number of SL transplants by having an often high Model for EndStage Liver Disease adult candidate offered a WL voluntarily agree to an SL have been largely unsuccessful. Conversely, a mandatory splitting policy modeled after the Italian experience, which resulted in an increase in SL transplants with a decrease in both pediatric and adult waitlist mortality, could be successful but likely contentious.(8) An alternative third option would be to confer some additional prioritization to adult candidates willing to accept an SL allograft within the framework of a continuous distribution model.(9) In this model, Abbreviations: SL, split liver; WL, whole liver.