The annual incidence of
fulminant hepatitis (FH) in Japan has decreased from 3700 patients in 1972 to 1000 patients in 1989, 1050 patients in 1995 and 426 in 2004. The most frequent cause of FH in Japan is hepatitis B virus (HBV)-related
hepatitis, which accounts for around 40%, with
hepatitis A accounting for around 10%;
drug reaction accounts for around 10%; other
hepatitis, including an unknown cause, accounts for around 40%. The acute type FH, which has a disease duration as 10 days or shorter before the development of
encephalopathy (onset-
coma days [OCD]), mainly consists of
hepatitis A and B and has relatively better prognosis, with an approximately 40% survival rate without
transplantation. The subacute type FH, which has 11 to 56 days OCD, mainly consists of unknown
hepatitis including acute-onset
autoimmune hepatitis and has poorer prognosis of about 20% survival. Approximately 25% of FH patients underwent
liver transplantation and about 80% of them survived. High volume plasma exchange (PE) and
hemodialysis filtration (HDF) have been the most common and principal
therapies and they are administered to about 90% and 70% of patients, respectively. The progress of
artificial liver support such as combination treatment of PE with HDF is considered to play a role in the slight improvement of the survival proportion of patients with acute type FH in recent years.