How long does a patient have, if the are told there liver is completely damaged?

Who knows?: "completely damaged" is a very imprecise term so it is quite difficult to gauge the degree of injury and therefore longevity. Typically liver injury is graded with a meld score ( model of end stage liver disease) this number does not tell everything, but is a great starting point for finer discussion. If one gets a liver transplant then longevity is calculated by the transplant team.

MELD and Childs-Pugh: You can get average survival or mortality data from tools used initially for determine surgical candidates for cirrhosis pts. Search online for childs-pugh calculator and prognosis (the fluid drained is called ascites) (and compare with meld calculator and prognosis). You will need to talk to your doctor about individualizing data from studies on patients that may not apply to your situation.

End Stage Liver: Mayo end-stage liver dz model looks atserum bilirubin, serum creatinine, & the international normalized ratio for prothrombin time (inr) to predict 3 mos survival. It is calculated according to the following formula: meld = 3.78[ln serum bilirubin (mg/dl)] + 11.2[ln inr] + 9.57[ln serum creatinine (mg/dl)] + 6.43. Essentially >40 is a grim prognosis. <9 is excellent. Look up everything in-between.

MELD score.: Best prognosis is based on your meld ( model for end stage liver disease) score. You will need your doc to help you calculate this ( can use on-line calculator) and review survival curves, but as noted above 3 month survival is really good if meld <20 and really poor if meld > 40.