Living donor liver transplants (LDLT) for recipients with the most urgent need for a liver transplant in the next 3 months – a model for end-stage liver disease (MELD) score of 25 or higher – have become more frequent during the past decade, according to new findings presented at the annual meeting of the American Association for the Study of Liver Diseases.
Among LDLT recipients, researchers found comparable patient and graft survival at low and high MELD scores. But among patients with high MELD scores, researchers found lower adjusted graft survival and a higher transplant rate among those with living donors, compared with recipients of deceased donor liver transplantation (DDLT).
The findings suggest certain advantages of LDLT over DDLT may be lost in the high-MELD setting in terms of graft survival, said Benjamin Rosenthal, MD, an internal medicine resident focused on transplant hepatology at the Hospital of the University of Pennsylvania, Philadelphia.
“Historically, in the United States especially, living donor liver transplantation has been offered to patients with low or moderate MELD,” he said. “The outcomes of LDLT at high MELD are currently unknown.”
Previous data from the Adult-to-Adult Living Donor Liver Transplantation Cohort Study (A2ALL) found that LDLT offered a survival benefit versus remaining on the wait list, independent of MELD score, he said. A recent study also has demonstrated a survival benefit across MELD scores of 11-26, but findings for MELD scores of 25 and higher have been mixed.
Trends and outcomes in LDLT at high MELD scores
Dr. Rosenthal and colleagues conducted a retrospective cohort study of adult LDLT recipients from 2010 to 2021 using data from the Organ Procurement and Transplantation Network (OPTN), the U.S. donation and transplantation system.
In baseline characteristics among LDLT transplant recipients, there weren’t significant differences in age, sex, race, and ethnicity for MELD scores below 25 or at 25 and higher. There also weren’t significant differences in donor age, relationship, use of nondirected grafts, or percentage of right and left lobe donors for LDLT recipients. However, recipients with high MELD scores had more nonalcoholic steatohepatitis (29.5% versus 24.6%) and alcohol-assisted cirrhosis (21.6% versus 14.3%).
The research team evaluated graft survival among LDLT recipients by MELD below 25 and at 25 or higher. They also compared posttransplant patient and graft survival between LDLT and DDLT recipients with a MELD of 25 or higher. They excluded transplant candidates on the wait list for Status 1/1A, redo transplant, or multiorgan transplant.
Among the 3,590 patients who had LDLT between 2010 and 2021, 342 patients (9.5%) had a MELD of 25 or higher at transplant. There was some progression during the waiting period, Dr. Rosenthal noted, with a median listing MELD score of 19 among those who had a MELD of 25 or higher at transplant and 21 among those who had a MELD of 30 or higher at transplant.
For LDLT recipients with MELD scores above or below 25, researchers found no significant differences in adjusted patient survival or adjusted graft survival.
Then the team compared outcomes of LDLT and DDLT in high-MELD recipients. Among the 67,279-patient DDLT comparator group, 27,552 patients (41%) had a MELD of 25 or higher at transplant.
In terms of LDLT versus DDLT, unadjusted and adjusted patient survival were no different for patients with MELD of 25 or higher. In addition, unadjusted graft survival was no different.
However, adjusted graft survival was worse for LDLT recipients with high MELD scores. In addition, the retransplant rate was higher in LDLT recipients, at 5.7% versus 2.4%.
The reason why graft survival may be worse remains unclear, Dr. Rosenthal said. One hypothesis is that a low graft-to-recipient weight ratio in LDLT can cause small-for-size syndrome. However, these ratios were not available from OPTN.
“Further studies should be done to see what the benefit is, with graft-to-recipient weight ratios included,” he said. “The differences between DDLT and LDLT in this setting should be further explored as well.”
The research team also described temporal and transplant center trends for LDLT by MELD group. For temporal trends, they expanded the study period from 2002-2021.
The found a marked U.S. increase in the percentage of LDLT with a MELD of 25 or higher, particularly in the last decade and especially in the last 5 years. But the percentage of LDLT with high MELD remains lower than 15%, even in recent years, Dr. Rosenthal noted.
Across transplant centers, there was a trend toward centers with increasing LDLT volume having a greater proportion of LDLT recipients with a MELD of 25 or higher. At the 19.6% of centers performing 10 or fewer LDLT during the study period, none of the LDLT recipients had a MELD of 25 or higher, Dr. Rosenthal said.
The authors didn’t report a funding source. The authors declared no relevant disclosures.