Demystifying Split Liver Transplantation in Adults: Factors Associated with Early Graft Survival in the New Era

BACKGROUND: Split liver transplantation (SLT) can expand the donor pool by generating 2 grafts from 1 organ. However, SLT only consists of <5% of United States liver transplants. Factors determining adequate SLT prognosis remain understudied. METHODS: A retrospective study of adult deceased-donor liver transplant recipients (January 2015 to September 2025) was conducted using the United Network for Organ Sharing/Organ Procurement and Transplantation Network database. The primary outcome was graft survival (GS) at 3 and 12 months. SLT recipients were analyzed by graft laterality, splitting technique, graft-to-recipient weight ratio (GRWR), and graft weight-to-standard liver volume (GW/SLV) ratio. Propensity score matching (PSM; 1:1) was used to compare SLT with whole liver transplantation (WLT), followed by sensitivity analyses. RESULTS: Among 840 SLT recipients, right lobe graft (RLG) demonstrated superior 12-month GS over left lobe graft (LLG) (91.7% vs 79.6%, respectively; P <.001), GRWR ≥ 0.8 outperformed GRWR < 0.8 (91.4% vs 85.3%, respectively; P =.045), and GW/SLV ≥ 0.45 outperformed GW/SLV < 0.45 (91.3% vs 83.0%, respectively; P =.032). Using propensity score-matched analysis, SLT demonstrated lower GS than WLT at 3 months (93.7% vs 96.6%, respectively; hazard ratio HR, 1.89; P =.03) and 12 months (89.8% vs 93.4%, respectively; HR, 1.60; P =.03). Sensitivity analyses revealed that this difference was driven by LLG (3-month HR, 6.62; 12-month HR, 4.03; both P <.001), GRWR < 0.8 (3-month HR, 4.39; P =.008; 12-month HR, 2.98; P =.02), and recipients aged ≥55 years (3-month HR, 2.05; P =.047; 12-month HR, 1.86; P =.03). RLG, GRWR ≥ 0.8, GW/SLV ≥ 0.45, and recipients aged <55 years demonstrated outcomes comparable with those of WLT. CONCLUSION: Within the SLT cohort, RLG, GRWR ≥ 0.8, and GW/SLV ≥ 0.45 were associated with superior early GS. Compared with the detrimental GS difference of WLT, the detrimental GS difference of SLT was attenuated with RLG, younger recipients, and adequately matched grafts.