INTRODUCTION
Hepatitis B virus (HBV) infection is a global public health problem. An estimated 350 million people worldwide are chronically infected with HBV. Approximately 500 000 die annually from HBV-related liver disease[1]. The prevalence and concerns to public health institutions about HBV infection vary according to geographical origin.
Individuals with chronic hepatitis B (CHB) are at increased risk of developing serious problems including liver cirrhosis, hepatic de-compensation and hepatocellular carcinoma (HCC). Fifteen to forty percent of these individuals will develop serious sequelae during their lifetime and have greater evolution to cirrhosis or HCC[2,3]. The 5-year rate of progression from CHB to cirrhosis is estimated to be 12%-20%[4–7]. In patients with cirrhosis, the 5-year cumulative risk of developing HCC is 17% in East Asia and 10% in Western Europe and the United States, and the 5-year liver-related death rate is 15% in Europe and 14% in East Asia[8,9]. Seropositivity for the hepatitis B surface antigen (HBsAg) is one of the most important risk factors for HCC[10]. Seropositivity for hepatitis B e antigen (HBeAg) is associated with an increased risk for HCC, and it is significant regardless of serum level of alanine aminotransferase (ALT) and status of liver cirrhosis[8,10,11]. The risk of progression appears to be greatest in patients who progress from an immunotolerant to an immune-clearance phase[12], in patients who have delayed HBeAg seroconversion[13], and in patients who have reactivation of HBV replication after HBeAg seroconversion[14–16].
Disease progression is variable and multifactorial. It is influenced by several factors including replicating activity of the virus, and host and environmental factors[17]. Four phases of CHB have been defined: immunotolerant phase, immune active phase, HBeAg seroconversion to anti-HBeAg, and inactive carrier.