What is the life expectancy of an 80 year old lady with hepatic encephalopathy?

Poor prognosis. Generally speaking hepatic encephalopathy occurs with advanced liver disease. Hepatic encephalopathy is associated with short survival in cirrhotic patients. Although these patients can be classified into several groups with a different prognosis, the survival probability in every group is lower than that currently expected after liver transplantation.http://www.ncbi.nlm.nih.gov/m/pubmed/10365817/.
Varies. The life expectancy depends on the cause of the liver disease. Hepatic encephalopathy is observed when brain function in impaired because toxins ordinarily removed by the liver are not, because the liver is not working. The causes of this kind of liver problem are multiple. The specific prognosis depends on the cause of the liver disease, how severe it is, and if there is any therapy for it etc..