To the Editor:
We read with interest the article of Braat et al.  The authors developed, using the Euro-Transplant database, a novel donor risk index (ET-DRI) in order to predict and stratify the outcome after liver transplantation. Like Feng and coauthors did for to the American DRI , the authors postulated that donor quality is the strongest determinant of recipient outcome. However, while DRI and ET-DRI are helpful in recognizing grafts with expected higher risk, both fail to provide information whether to accept or not a liver for a certain recipient. We feel that such a suggestion requires deeper investigation and discussion. The authors suggest that ET-DRI should be used in the allocation.1 Although several recipient parameters were tested (age, indication, MELD, urgency), established studies (3–7) on donor-to-recipient match (D2Rm) were not considered by the authors.1
The merits of the current MELD system are simplicity, objectivity and accuracy in predicting waiting list mortality, as well as equity, since disease severity is the only prioritizing factor. Disadvantages of the current system include a pressure toward poorer outcomes as the sickest (highest MELD) recipients often match with higher risk donors, resulting increased frequency of futile transplantations. Yet, the desire for a balance between utility and need in organ allocation has not been completely realized. Scientific efforts to improve utility by improving D2Rm (LYFT, life years from transplant) have been difficult to implement as allocation policy due to concerns about policy complexity and limiting of access for some recipient subgroups.
Intending to decrease the frequency of unsustainable donor-to-recipient matches, D-MELD was developed to account for the two dominant variables in the prediction of outcome, patient condition at transplant, as measured by MELD score, and donor quality, as measured by age [3, 4]. Being the product of two continuous variables, donor age and MELD, D-MELD produces a continuous risk-gradient predicting both increased postoperative mortality and length of stay. The original D-MELD model  has been further refined in the Italian study [4, 5] analyzing the risk in combination with recipient age, primary indication, portal vein status, retransplant status and center volume. Similar to D-MELD a novel score, BAR (BAlance of Risk) score , has been developed. Differently from the ET-DRI, the BAR score adds to donor age recipient age, MELD, retransplant status, need of mechanical ventilation and cold ischemia time (CIT).
The strength of currently developed D2Rm scores (SOFT , D-MELD [3,4] and BAR ) lies in the improved predictive ability analyzing the combination between donor–recipient factors. Furthermore, D-MELD and BAR, developed from the UNOS database, have been validated in Europe demonstrating superiority to other scores which include only donor or recipient factors (DRI, MELD). Those score have therefore a great potential to be helpful in deciding which organs should not be transplanted to high-risk candidates.
Therefore, ET-DRI should be compared to other D2Rm scores for both predictive accuracy and applicability across differing patient populations. However, scores should not determine or limit transplantation opportunities. Any proposal to improve utility in allocation should be vetted in open forum, fully recognizing the ethical, scientific and practical limitations.