Pre-transplant MELD and sodium MELD scores are poor predictors of graft failure and mortality after liver transplantation

Background Incorporating serum sodium concentrations into the model for end-stage liver disease (MELD) score may increase its sensitivity for identifying priority patients for orthotopic liver transplantation (OLT). We, therefore, evaluated and compared the ability of the sodium MELD and MELD scores to predict graft and patient survival after OLT. Methods The United Network for Organ Sharing (UNOS) registry includes all US adult OLTs performed between January 2000 and August 2008. For 15,156 patients who met inclusion criteria, MELD score was calculated; for 6,193 patients whose serum sodium concentrations was between 120 and 135 mEq/dl, immediately before OLT, sodium MELD score was calculated. The corresponding hazard ratios (HR) for MELD and sodium MELD on graft and patient survival were assessed using the Cox proportional hazards regression models. The concordance probability estimate (CPE) was used to evaluate predictive ability of each time-to-event model. Results MELD and sodium MELD scores were both significant predictors in univariable Cox regression models for graft failure [HR (95% CI) for every 10 units increase in the predictor: 1.10 (1.04, 1.17), P = 0.001, and 1.05 (1.00, 1.10), P = 0.03, respectively], and for mortality (1.14 (1.07, 1.21), P < 0.001, and 1.07 (1.02, 1.12), P = 0.01, respectively), with CPE of 0.52-0.53. Conclusion While MELD and sodium MELD were each significantly associated with survival after OLT, their predictive abilities were poor. The sodium MELD score does not improve prediction accuracy over the MELD score. Weak prediction may result from unaccounted variability in recipient and donor status, as well as surgical and postoperative factors.