All Chinese CHB patients who were followed up in the Hepatitis Clinic, Department of Medicine, Queen Mary Hospital, Hong Kong, during the period from January 1976 to December 2000 were recruited. A total of 346 patients who already had cirrhosis related complications including ascites, spontaneous bacterial peritonitis (SBP), oesophageal varices, encephalopathy, or HCC (collectively termed as “complications”) on presentation were excluded from the study. Patients with hepatitis C (n
25) and hepatitis D (n
10) coinfection, a history of significant alcohol consumption (n
19), evidence of coexisting autoimmune hepatitis (n
4), Wilson’s disease (n
5), or primary biliary cirrhosis (n
5) were also excluded. In addition, 494 patients who received interferon, lamivudine, or other investigational modalities for the treatment of CHB were excluded because these would not represent the natural history of the disease. The long term outcome of interferon treated patients has been analysed and published separately.11
All of the studies of interferon included patients with normal as well as elevated ALT levels. Their exclusion should not bias the outcome of our current analysis.
All patients were positive for hepatitis B surface antigen by micro-particle enzyme immunoassay (MEIA; Abbott Laboratories, Chicago, Illinois, USA) for at least six months. HBeAg and antibodies to HBeAg (anti-HBe) (ELISA; Abbott Laboratories), liver biochemistry, and α fetoprotein (AFP) were checked every 3–6 months. Continual clinical assessments, including the development of ascites, were carried out during each follow up. Patients with significant symptoms or abnormalities in blood tests were recalled and, if necessary, admitted to hospital. HBV DNA levels were measured by the Digene Hybrid Capture assay (Digene Corporation, Gaithersburg, Maryland, USA; lower limit of detection 140 000 copies/ml). In order to determine HBV DNA levels at relatively low titre, HBV DNA levels of all anti-HBe positive patients were determined again using a polymerase chain reaction (PCR) based assay (Cobas Amplitor HBV Monitor Test; Roche Diagnostics, Branchburg, New Jersey; lower limit of detection 200 copies/ml).
Patients with ALT levels that were increased to 1.5 times the upper limit of normal (ULN) (upper limit: 53 and 31 U/l for males and females, respectively) were defined as having exacerbation of chronic HBV infection if other common causes of ALT elevation were excluded, including other viral hepatitis, drug induced hepatitis, alcoholic hepatitis, and steatohepatitis. Peak ALT, peak bilirubin, peak AFP levels, and duration for each exacerbation were noted.
HBeAg seroconversion was defined as loss of HBeAg with development of anti-HBe on at least two consecutive follow up visits.
Ultrasonogram was arranged for patients with elevated AFP (>20 ng/ml) if ALT was normal and for patients with persistently elevated AFP even if ALT was raised. Computer tomography and/or hepatic angiogram was performed if ultrasound showed suspicion of HCC. For patients with clinical detection of ascites, splenomegaly, or persistently low albumin of <35 g/l, a screening oesophageogastroduodenoscopy was performed for detection of oesophageal varices. The occurrence of complications and survival time were recorded.
All statistical analyses were performed using the Statistical Program for Social Sciences (SPSS 10.0 for Windows; SPSS Inc., Chicago, Illinois, USA). Normality of the distribution of continuous variables was tested by the Komolgorov-Smirnov test. The Mann-Whitney U test was used for continuous variables with skewed distribution and the χ2 test with Yates’ correction factor or Fisher’s exact test was applied for categorical variables. Differences in paired parameters were tested by the Wilcoxon signed ranks test. The Kaplan-Meier method using the log rank test was applied for calculation of the cumulative risk of development of complications and survival. The Cox hazard proportional model was used to test the associations between different variables and the development of complications and survival.