International multicenter study of ultralow graft-to-recipient weight ratio grafts in adult living donor liver transplantation

Decreasing the graft size in living donor liver transplantation (LDLT) increases the risk of early allograft dysfunction. Graft-to-recipient-weight-ratio (GRWR) of 0.8 is considered the threshold. There is evidence that smaller volume grafts may also provide equally good outcomes, the cut-off of which remains unknown. In this retrospective multi-center study, 92 adult LDLT with a final GRWR<=0.6 performed at 12 international liver transplant (LT) centers over a 3-year period were included. Perioperative data including preoperative status, portal flow hemodynamics (PFH) and portal flow modulation (PFM), development of SFSS, morbidity and mortality was collated and analyzed. Thirty-two (36.7%) patients developed SFSS and this was associated with increased 30-day, 90-day and one-year mortality. Pre-operative MELD and inpatient status were independent predictors for SFSS (p<0.05). Pre-LT renal dysfunction was an independent predictor of survival (Hazard ratio- 3.1;95% ci 1.1,8.9, p=0.035). PFH or PFM were not predictive of SFSS or survival. We report the largest ever multi-center study of LDLT outcomes using ultralow-GRWR grafts and for the first-time validate the ILTS-iLDLT-LTSI consensus definition and grading of SFSS. Pre-operative recipient condition rather than GRWR and PFH were independent predictors of SFSS. Algorithms to predict SFSS and LT outcomes should incorporate recipient factors along with GRWR.