Extreme Hyponatremia as a Risk Factor for Early Mortality after Liver Transplantation in the MELD-Sodium Era

Background: The impact of hyponatremia on waitlist and post-transplant outcomes following the implementation of MELD-Na based liver allocation remains unclear. We sought to evaluate waitlist and post-liver transplant (LT) outcomes in patients with hyponatremia before and after implementation of MELD-Na based allocation.Methods: Adult primary LT candidates between 2009 and 2019 were identified in the OPTN/UNOS database. Multi-organ transplants and re-LT were excluded. Two eras were defined: before and after implementation of MELD-Na based allocation. Patients were categorized into the following groups: extreme hyponatremia (≤120 mEq/L), severe hyponatremia (121-124), moderate hyponatremia (125-129), mild hyponatremia (130-134), normal sodium (135-145), and hypernatremia (>145). 90-day waitlist outcomes and post-LT survival were compared according to era and sodium concentration using Fine-Gray and Cox proportional hazard models.Results: 87,845 patients were included in waitlist outcome analyses (N=64,911[pre- MELD-Na], N=22,934[post-MELD-Na]). In the pre-MELD-Na era, extreme hyponatremia at listing was associated with increased risk of 90-day waitlist mortality (HR:2.08,pConclusions: With the introduction of MELD-Na based allocation, waitlist outcomes have improved in patients with extreme hyponatremia but paradoxically been associated with worse short-term post-LT survival.