Value and limitations of the BAR-score for donor allocation in liver transplantation

The MELD-score was shown to be able to predict 90-day mortality in most patients with end-stage liver disease prior to liver transplantation and is used as a widely accepted measure for transplantation urgency. Prognostic ability of the BAR-score to predict 90-day post-transplant mortality by detection of unfavourable pretransplant combinations of donor and recipient factors may help to better balance urgency versus utility.

Two German cohorts (Hannover, n=453; Kiel, n=234) were retrospectively analyzed using ROC-curve analysis, goodness-of-model-fit tests, summary measures and risk-adjusted multivariate binary regression. Included were all consecutive liver transplants performed in adult recipients (minimum age 18 years). Excluded were all combined transplants and living-related organ donor transplants.

Risk-adjusted multivariate regression revealed that the BAR-score is an independent risk factor for 90-day mortality after transplantation in both cohorts from Hannover and Kiel combined (p<0.001, OR=1.017, 95% CI:1.031-1.113). The area under the ROC-curve (AUROC) for the prediction of 90-day mortality using the BAR-score was 0.662 (95% CI 0.624-0.699, power>95%). Measures for association between observed 90-day mortality and the predicted probabilities in the combined cohort were concordant in 63.5% with low summary measures (Somers' D test 0.32, Goodman-Kruskal Gamma test 0.34 and Kendall's Tau a test 0.07).

The BAR-score performed below accepted thresholds for potentially useful clinical prognostic models. Prognostic models with better predictive ability with AUROCs>0.700, concordance>70% and larger summary measures are required for the prediction of 90-day post-transplant mortality to enable donor organ allocation with reliable weighing of urgency versus utility.