Department of Medicine, A M Migliavacca Center for Liver Diseases and First Division of Gastroenterology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy.
Chronic infection with the Hepatitis B and the Hepatitis C virus represent major health problems worldwide, as it is estimated that roughly 400 and 200 million people are infected by each virus. By definition any antiviral therapy that claims to be effective should have as its ultimate efficacy endpoint an improvement in patients' survival, or at least a reduction in the development rates of liver related complications. However, this is extremely complicated to prove as the natural course of both viral diseases is extremely slow, requiring decades to evolve in cirrhosis and even more years to determine liver complications. For this reason clinicians and health authorities have relied on so called surrogate endpoints to assess the efficacy of any therapeutic intervention for viral hepatitis. Obviously, this allows for standardization in study designs that ultimately translates into an accelerated time frame for therapeutic drugs as well as healthcare innovations to enter the viral hepatitis clinical practice. However, it also calls for demonstration that surrogate endpoints in the treatment of patients with chronic hepatitis B or C are good and reliable markers of long-term efficacy.