Liver transplant recipient survival benefit with living donation in the model for endstage liver disease allocation era

Following the introduction of adult-to-adult living donor liver transplantation (LDLT) in the U.S. in the late 1990’s the procedure gained in popularity, and in 2001 represented approximately 8% of all adult liver transplants performed in the U.S. Subsequently, use of the procedure declined from 412 cases in 2001 to 168 LDLT in the U.S in 2009 (www.optn.transplant.hrsa.gov accessed 08/13/10). Previous retrospective reports by the Adult-to-Adult Living Donor Liver Transplantation Cohort Study (A2ALL) identified a survival benefit for patients who received LDLT as compared to waiting for, or receiving, a deceased donor liver transplant (DDLT).(1)That report employed data accrued over the early years of LDLT in nine active liver transplant centers in the U.S. More than 70% of the potential liver transplant recipients enrolled in that retrospective cohort study were evaluated in the era before the Model for End-Stage Liver Disease (MELD) score was employed for deceased donor liver allocation in the U.S. (February 28, 2002), and thus the benefits of pursuing LDLT as compared to waiting for deceased donor liver transplant (DDLT) in the MELD allocation era are not well understood. Moreover, there is considerable uncertainty regarding which populations of adult liver transplant candidates benefit most from receipt of LDLT in comparison to awaiting DDLT. Markov modeling suggested benefit associated with receipt of LDLT in patients with hepatocellular carcinoma (HCC) (2,3) compared with waiting for DDLT. Experience from A2ALL, however, demonstrated higher rates of post-transplant recurrence in liver transplant candidates with HCC who underwent LDLT(4). Similarly, there is uncertainty regarding whether there is a survival benefit associated with receipt of LDLT among transplant candidates with MELD<15. Two recent large database analyses of the U.S liver transplant population have suggested that a survival benefit is obtained by transplant candidates undergoing transplantation with MELD scores in excess of 15(5) or 12(6) in comparison to remaining on the waiting list. Analyses from the retrospective cohort study reported by A2ALL suggested a survival benefit for transplant candidates enrolled in A2ALL with laboratory (non-exception) MELD scores less than 15, although the majority of those patients were actually transplanted in the pre-MELD allocation era (1). To resolve some of the uncertainties delineated above, and better inform liver transplant candidates regarding transplant outcomes in the current allocation paradigm, we examined data from A2ALL for liver transplant candidates who entered into the study following the introduction of the MELD-based liver allocation system on February 28, 2002 through August 31, 2009. Outcomes for these patients who presented to A2ALL transplant centers with their first potential living donor during this period were analyzed in order to assess the potential benefit of receipt of LDLT based on transplant candidate MELD score and presence or absence of HCC. The study design, which examined patient outcomes from the time of first living donor evaluation, was created to allow clinicians to counsel transplant candidates and their donors when the opportunity for LDLT presented itself in the transplant clinic setting.