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Chapter 2.1
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been hepatitis B surface antigen (HBsAg) positive for >6 months, were HBeAg positive
on two occasions within 8 weeks prior to enrolment, had elevated serum ALT levels of
2 - 10 times the upper limit of normal (ULN), and had a serum HBV DNA level >1.0 x
105 copies/mL. Major exclusion criteria were: antiviral therapy within 6 months prior to
enrolment, presence of viral co-infections, pre-existing cytopenia or decompensated
liver disease. Treatment comprised of PEG-IFN alfa-2b 100 μg weekly (PegIntron, Merck,
Whitehouse Station, NJ, USA) for 52 weeks. The dose of PEG-IFN was reduced to 50
μg after 32 weeks of treatment. 16 The 167 patients who received placebo for 48 weeks
were eligible for the original study if they had been HBsAg positive for >6 months,
had a serum HBV DNA level ≥1 x 106 copies/mL and an ALT level of 1.2 -10 x ULN. Key
exclusion criteria were antiviral therapy within 6 months prior to enrolment, presence of
viral co-infections or decompensated liver disease. 10
Laboratory tests
Serum HBV DNA levels were measured with 4-week intervals. For the PEG-IFN study,
an in-house developed TaqMan PCR assay based on the EuroHep standard was used
(lower limit of detection 400 copies/mL). 17 For the placebo group, the Roche Amplicor
Monitor PCR assay was used. 10 An excellent correlation between these assays has previously
been shown. 18 Serum ALT levels were measured using automated techniques and
are expressed as values representing a ratio to the upper limit of the normal range
(ULN). Determination of HBsAg and HBeAg was performed with the use of commercially
available enzyme immunoassays. HBV genotypes were assigned by INNO-LiPa assay
(Innogenetics, Gent, Belgium) or by phylogenetic analyses of HBV DNA sequences in
the PEG-IFN and placebo group, respectively. 19
Statistical analysis
Continuous variables are expressed as means ± standard deviation (SD) or medians
with interquartile range (IQR), where appropriate. Comparisons between groups were
made using the Chi-square test or Fisher’s exact test for categorical variables and the
t-test or Mann-Whitney test for continuous variables. Patterns of HBV DNA decline were
modelled using linear mixed regression analysis with a heterogeneous autoregressive
covariance structure depending on treatment regimen (PEG-IFN versus placebo).
Declines of HBV DNA were compared for patients with and without response, defi ned as
HBeAg negativity at the end of treatment (EOT), by extending the model with response
and interaction terms with treatment and time. The estimated declines of HBV DNA are