Effects of Allocating Livers for Transplantation Based on Model for End-Stage Liver Disease–Sodium Scores on Patient Outcomes

Abstract

The Model for End-stage Liver Disease and Sodium (MELD-Na) score was introduced for liver allocation in January 2016. We evaluated the effects of liver allocation, based on MELD-Na score, on waitlist and post-transplantation outcomes. We examined 2 patient groups from the United Network for Organ Sharing registry; the MELD-period group was composed of patients who were registered as transplant candidates from June 18, 2013 through January 10, 2016 (n= 18,850) and the MELD-Na period group was composed of patients who were registered from January 11, 2016 through September 30, 2017 (n= 14,512). We compared waitlist and post-transplantation outcomes and association with serum sodium concentrations between groups. Mortality within 90 days on the liver waitlist decreased (hazard ratio [HR] 0.738, P < .001) and transplantation probability increased significantly (HR 1.217, P < .001) in the MELD-Na period. Although mild, moderate, and severe hyponatremia (130-134, 125-129, and <125 mmol/L) were independent risk factors for waitlist mortality in the MELD period (HR 1.354, 1.762, and 2.656; P< .001, P < .001, and P < .001, respectively) compared with the reference standard (135-145 mmol/L), these adverse outcomes were decreased in the MELD-Na period (HR 1.092, 1.271 and 1.374; P= .27, P= .018, and P= .037, respectively). The adjusted survival benefit of transplant recipients vs patients placed on the waitlist in thesame scorecategories was definitive for patients with MELD-Na scores of 21-23 in the MELD-Na era (HR 0.336, P<.001) compared with MELD scores of 15-17 in the MELD era (HR0.365, P < .001). Liver allocation basedon MELD-Na score successfully improved waitlist outcomes and provided significant benefit to hyponatremic patients. Given the discrepancy in transplantation survival benefit, the current rules for liver allocation might require revision.