Refitting the Model for End-Stage Liver Disease for the Eurotransplant Region

Abstract

Background and Aims: The United Network for Organ Sharing’s Model for End-Stage Liver Disease (UNOS-MELD) score is the basis of liver allocation in the Eurotransplant region. It was constructed 20 years ago in a small US cohort and has remained unchanged ever since. The best boundaries and coefficients were never calculated for any region outside the United States. Therefore, this study refits the MELD (reMELD) for the Eurotransplant region. Approach and Results: All adult patients listed for a first liver transplantation between January 1, 2007, and December 31, 2018, were included. Data were randomly split in a training set (70%) and a validation set (30%). In the training data, generalized additive models with splines were plotted for each MELD parameter. The lower and upper bound combinations with the maximum log-likelihood were chosen for the final models. The refit models were tested in the validation data with C-indices and Brier scores. Through likelihood ratio tests the refit models were compared to UNOS-MELD. The correlation between scores and survival of prioritized patients was calculated. A total of 6,684 patients were included. Based on training data, refit parameters were capped at creatinine 0.7-2.5, bilirubin 0.3-27, international normalized ratio 0.1-2.6, and sodium 120-139. ReMELD and reMELD-Na showed C-indices of 0.866 and 0.869, respectively. ReMELD-Na prioritized patients with 1.6 times higher 90-day mortality probabilities compared to UNOS-MELD. Conclusions: Refitting MELD resulted in new lower and upper bounds for each parameter. The predictive power of reMELD-Na was significantly higher than UNOS-MELD. ReMELD prioritized patients with higher 90-day mortality rates. Thus, reMELD(-Na) should replace UNOS-MELD for liver graft allocation in the Eurotransplant region.