The Survival Benefit of Pediatric Liver Transplantation

Purpose: The anticipated survival benefit of liver transplantation (LT) is an important factor guiding transplant eligibility and organ allocation policies. We hypothesized that the true survival benefit of pediatric LT has been underestimated due to long life spans after transplant and limited follow-up data beyond 30 years- the length of the modern era of LT. Here, we propose a novel approach to estimating the survival benefit of pediatric LT by modeling recipient survival beyond the observed time window. 
Methods: We analyzed 260,121 adult and 20,755 pediatric patients listed for first LT in the UNOS STAR files (1990-2024). We defined the observed survival benefit as the difference in restricted mean survival time between patients who were transplanted, and those who were waitlisted but not transplanted until the end of available follow-up data, which represents the area between their Kaplan-Meier curves. To extend survival estimates beyond observed data, we calculated age-specific mortality rates for LT recipients who survived at least 2 years after LT. Using these mortality rates, we simulated the long-term survival of pediatric LT recipients beyond the end of their follow-up data. We used propensity score matching based on age, year of listing, listing status, blood type, diagnosis, dialysis status, region, sex, and PELD score to generate a control group of patients who were waitlisted but not transplanted. We defined the simulated survival benefit as the difference in restricted mean survival time until age 90 between pediatric LT recipients and controls. We repeated simulations 1000 times to obtain 95% confidence intervals. 
Results: The observed survival benefit of LT in the UNOS data to date was 9.9 years for adult and 13.6 years for pediatric LT recipients (Figure 1a). Simulating survival beyond the observed data increased the survival benefit to 33.4 (95%CI 33.0-33.7) years for pediatric LT recipients (Figure 1b). The simulated survival benefit was greatest for children transplanted for primary liver malignancy at 36.6 (95%CI 35.2-37.8) years and lowest for primary sclerosing cholangitis at 25.3 (95% CI 21.3-27.5) years (Table 1). 

Conclusions: The true survival benefit of pediatric LT appears to be far greater than previously estimated, due to excellent long-term survival beyond the perioperative period. This finding has important implications for liver allocation policies.