Clinical epidemiology of fulminant hepatitis in Japan.

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.