Abstract
INTRODUCTION: Ensuring both graft survival and donor safety with old liver donors remains an important issue in living donor liver transplantation (LDLT). This study aimed to evaluate recipient and donor outcomes based on donor age and to identify risk factors associated with graft loss in LDLT involving old donors. MATERIALS AND METHODS: We included 4035 LDLT cases from a multicenter cohort, categorizing donors as "old" or "young" based on an age cutoff of 50 years determined by a restricted cubic spline. After 1:3 propensity score matching, graft survival was compared between the groups. Risk factors for graft loss in old versus young donor LDLT were investigated through interaction analysis, with outcomes stratified by the number of risk factors. RESULTS: The old-donor group ( n = 374; 9.3%) showed significantly lower 5-year graft survival than the young-donor group ( n = 3661; 90.7%) in the matched cohort (79.6% vs. 87.7%, P = 0.004). Old-donor was an independent risk factor for graft loss [adjusted hazard ratio (HR): 1.56, 95% CI: 1.17-2.07, P = 0.002]. Significant interactions affecting graft survival in old-donor LDLT compared to young-donor LDLT included cold ischemic time (CIT) ≥ 150 min, Model for End-stage Liver Disease (MELD) score ≥ 20, and recipient BMI ≥ 25 kg/m 2 . Old-donor LDLT with two or more of these risk factors increased the risk of graft loss (HR 3.78, 95% CI: 1.97-7.26, P < 0.001). Six-month donor complication rates did not differ by age ( P = 0.672). CONCLUSIONS: LDLT using grafts from old donors (≥50 years) showed poorer graft survival, especially when two or more of the following were present: CIT ≥ 150 min, MELD ≥ 20, or recipient BMI ≥ 25 kg/m 2 . These risk factors should be carefully considered when selecting older living donors.