Outcomes and Risk Factors for Liver Transplantation Using Graft-to-Recipient Weight Ratio Less Than 0.8 Graft from Living Donors: Multicentric Cohort Study

Objective: To compare graft survival after living donor liver transplantation (LDLT) in patients receiving graft-to-recipient weight ratio (GRWR) <0.8 versus GRWR≥0.8 grafts and identify risk factors for graft loss using GRWR<0.8 grafts. Background: Favorable outcomes after LDLT using GRWR<0.8 grafts were recently reported; however, these results have not been validated using multicenter data. Methods: This multicentric cohort study included 3450 LDLT patients. Graft survival was compared between 1:3 propensity score-matched groups and evaluated using various Cox models in the entire population. Risk factors for graft loss with GRWR<0.8 versus GRWR≥0.8 grafts were explored within various subgroups using interaction analyses, and outcomes were stratified according to the number of risk factors. Results: In total, 368 patients (10.7%) received GRWR<0.8 grafts (GRWR<0.8 group), whereas 3082 (89.3%) received GRWR≥0.8 grafts (GRWR≥0.8 group). The 5-year graft survival rate was significantly lower with GRWR<0.8 grafts than with GRWR≥0.8 grafts (85.2% vs 90.1%, P=0.013). Adjusted hazard ratio for graft loss using GRWR<0.8 grafts in the entire population was 1.66 (95% CI: 1.17-2.35, P=0.004). Risk factors exhibiting significant interactions with GRWR<0.8 for graft survival were age ≥60 years, Model for End-stage Liver Disease score ≥15, and male donor. When ≥2 risk factors were present, GRWR<0.8 grafts showed a higher risk of graft loss compared with GRWR≥0.8 graft in LDLT (hazard ratio 2.98, 95% CI: 1.79-4.88, P<0.001). Conclusions: GRWR<0.8 graft showed inferior graft survival than controls (85.2% vs 90.1%), especially when ≥2 risk factors for graft loss (among age 60 years or above, Model for End-stage Liver Disease score ≥15, or male donor) were present.