**3. Outcome of liver transplant in acute liver failure**

In Europe LT due to acute or subacute liver failure accounts for some 8% of LT. Patient survival after LT for this reason is 79, 71, 69 and 61%, at 1, 3, 5 and 10 years, respectively [29]. This survival rate is slightly lower during the initial years (first and third) than LT for other reasons but then becomes similar. Most deaths occur between the first and third years posttransplant due, mainly, to neurologic complications and sepsis [30]. Some centers have reported survival rates of up to 86% [31]. Overall survival is probably greatly influenced by patient age, with data from the European Transplant Registry showing 1- and 5-year survival of 51 and 42% in patients older than 60 years [29].

#### **3.1. Factors influencing the results**

Multiple factors have been associated with the outcome of patients who receive a LT due to ALF. Three studies [4, 32, 33] have identified a recipient age above 45–50 years as a poor prognostic factor, attributing this to the reduction in physiologic reserve with effect from these ages [4]. A body mass index (BMI) >29 was identified in one study [32]. On the other hand, no specific factor associated with the severity of the ALF, such as coagulopathy, has been found to be associated with a poor prognosis, although the degree of kidney failure, mechanical ventilation, and the use of inotropic drugs were found to be predictive factors in these studies. Such donor characteristics as age >60 years, ABO incompatibility [34, 35], and the use of a split or small liver have also been related with worse results [18, 36].

Survival has improved greatly over the last decade. This is the result of better management of ALF patients, leading to a lower incidence of pretransplant complications (e.g., renal failure, respiratory problems, sepsis), a lower grade of encephalopathy, and the use of more isogroup grafts. Identification of prognostic factors as well as the creation of transplant indication criteria like the Clichy [37] or King's College [16] criteria has also contributed to this improvement. The earlier indication for transplant, which in turn contributes to the use of more compatible organs and the patient receiving the transplant in better conditions, has been the foundation for the improvement in results over recent years.

The rapid localization of organs for transplant in ALF patients is an important factor that has also contributed greatly to the better results. In countries like Spain, with a high donation rate, it proves relatively easy to find a compatible organ fairly quickly, with 50% of these patients receiving a transplant within 24 h of becoming active on the waiting list, while the mean time to transplant is 40 h. In Spain this has resulted in only around 7% of ALF patients dying while still on the waiting list compared with 30% in the USA [38].

Thus, the optimal selection of candidates for transplant plus the identification of poor prognostic factors and the exclusion of those patients who will not benefit from LT due to their situation have contributed to the improved results. The development of extracorporeal bioartificial systems, improved organ procurement, and the use of organs from living donors can all contribute to future improvements.
