[Allocation systems in transplantation medicine: Advantages and disadvantages].

Donor organs for transplantations are a scarce commodity; therefore, allocation systems are needed that guarantee an ethically acceptable distribution to patients on the waiting list (equal treatment and fairness) but also take the probability of survival of the transplant in each recipient into consideration. In this article the allocation systems for lung, liver, kidney and pancreas transplants are presented.For lung transplantations an allocation system based on the lung allocation score (LAS) is currently used. The LAS predicts the probability of survival on the waiting list and the survival rate following transplantation. Organs with a limited range of utilization are distributed in a so-called mini-match procedure.For post-mortem kidney and pancreas transplantations a relatively complex but transparent allocation system has been created in which patients are subdivided into groups, each of which has its own allocation rules. The allocation is principally carried out according to criteria of fairness of distribution and according to the prospects of success. The probability of a mismatch also plays a role. The urgency is important for children and for patients who do not have the possibility of dialysis. Combined pancreas and kidney transplantations have priority over kidney transplantations alone.The criterion for the urgency of liver transplantation in Germany is currently the model for end-stage liver disease (MELD), which aims to reduce the waiting list mortality and to prioritize transplantations for those most in need. Because the system insufficiently describes the priority of transplantation for patients with tumors or genetic liver diseases, there is an additional set of rules for so-called standard exceptions.