©2013 International Medical Press 1359-6535 (print) 2040-2058 (online) 599
Antiviral Therapy 2013; 18:599–606 (doi: 10.3851/IMP2502)
Background: IL-21R polymorphisms have been identified
as potential predictors of virological outcomes in Western
chronic hepatitis C (CHC) patients receiving interferon-
based treatment. We aimed to examine the associations
of IL-21R genotypes and serum IL-21 levels with virologi-
cal responses to interferon-based treatment in Asian CHC
Methods: Genomic and clinical data were collected from
178 consecutive Taiwanese HCV genotype 1 patients
who received interferon-based therapy and 72 non-HCV
healthy subjects. Among them, serum IL-21 levels, IL-
21R and IL-28B genotypes were determined in 124 CHC
patients and healthy controls.
Results: Among patients with IL28B rs8099917 non-TT
genotypes, patients with IL-21R rs3093390 CC genotype
had a higher sustained virological response rate than
those with non-CC genotypes (CC versus non-CC 14/24
versus 0/4; P=0.031). Compared with non-HCV controls,
CHC patients had higher serum IL-21 levels (mean ±sd HCV
versus non-HCV 377.8 ±780.9 versus 70.5 ±33.2 pg/ml;
P=0.001). Patients with sustained virological response had
higher pretreatment serum IL-21 levels than those with-
out (adjusted OR 0.23, 95% CI 0.07, 0.80; P=0.021).
Conclusions: CHC patients have higher serum IL-21 lev-
els than healthy adults. Higher pretreatment serum IL-21
levels and IL-21R polymorphisms may serve as potential
factors predictive of treatment outcomes in CHC patients
with interferon-based therapy.
HCV infection is the leading cause of liver diseases and
liver transplantation worldwide . Although inter-
feron (IFN)-based therapy is still used as the standard
care of HCV infection in many parts of the world,
it remains expensive, has many unpleasant adverse
effects, and is only effective in a certain proportion of
chronic hepatitis C (CHC) patients [2,3]. Therefore,
several predictors are used clinically to access the ben-
efits and risks of treatment in CHC patients [4–13].
Among these factors, viral kinetic parameters following
antiviral therapy [14,15] and single nucleotide poly-
morphisms (SNPs) near the IL28B gene [16–21] have
been recognized as the most outweighing predictors
and widely used in daily clinical practice for the assess-
ment of IFN-based therapy.
Of particular note, several studies have implied an
important role of interleukin (IL)-21 in controlling
chronic viral infections, including HIV, HBV and HCV
infections [22–24]. For example, serum IL-21 levels
may be used as a biomarker to predict hepatitis B e
antigen seroconversion in chronic hepatitis B patients
treated with telbivudine . Moreover, genome-
wide association studies have identified the SNP near
the IL-21R gene (rs3093390) as a potential predictor
IL-21R gene polymorphisms and serum IL-21 levels
predict virological response to interferon-based
therapy in Asian chronic hepatitis C patients
Ching-Sheng Hsu1,2, Shih-Jer Hsu3,4, Wei-Liang Liu3, Chi-Ling Chen3, Chun-Jen Liu3,5, Pei-Jer Chen3,5,6,
Ding-Shinn Chen3,5, Jia-Horng Kao3,5,6,7*
1Division of Gastroenterology, Department of Internal Medicine, Buddhist Tzu Chi General Hospital, Taipei Branch, Taipei, Taiwan
2School of Medicine, Tzu Chi University, Hualien, Taiwan
3Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
4Department of Internal Medicine, National Taiwan University Hospital, Yun-Lin Branch, Yun-Lin County, Taiwan
5Department of Internal Medicine, National Taiwan University College of Medicine and National Taiwan University Hospital, Taipei, Taiwan
6Hepatitis Research Center, National Taiwan University College of Medicine and National Taiwan University Hospital, Taipei, Taiwan
7Department of Medical Research, National Taiwan University College of Medicine and National Taiwan University Hospital, Taipei, Taiwan
*Corresponding author e-mail: email@example.com
©2013 International Medical Press 600
C-S Hsu et al.
for the therapeutic response in CHC patients . A
recent study also indicated that dysregulation of innate
immunity might impair viral kinetics and therapeutic
response in HCV genotype 1 patients with the unfa-
vourable IL28B genotype . Therefore, it is reason-
able to hypothesize that the IL-21 and IL-21R genes
might have a link to HCV infection, and could affect
the therapeutic response to IFN-based therapy in CHC
patients. We therefore examined the associations of
serum IL-21 levels and IL-21R rs3093390 genotype
with virological responses in CHC patients receiving
IFN-based treatment. In addition, the serial changes of
serum IL-21 levels following IFN-based therapy were
compared between patients with and without favour-
able virological responses.
A total of 178 chronic HCV genotype 1 patients who
received IFN-based therapy were consecutively enrolled
from the gastroenterological clinics of the National
Taiwan University Hospital (Taipei, Taiwan) and its
Yun-Lin branch (Yun-Lin County, Taiwan). Among
them, 124 patients had available virological data and
stored serum samples. Chronic HCV infection was
defined as the positivity of both anti-HCV and serum
HCV RNA for >6 months. All patients were naive to
IFN treatment and other experimental antiviral or
immunosuppressive therapy. They had serum alanine
aminotransferase (ALT) levels ≥2× the upper limit of
normal (ULN) on two occasions within the previous
6 months. None of them were positive for hepatitis B
surface antigen (HBsAg) or HIV antibody, or had a
known history or serological evidence of autoimmune
liver disease, inheritable disorders such as hemochro-
matosis or Wilson’s disease, renal insufficiency, malig-
nancy, a history of daily alcohol consumption >20 g or
active drug abuse.
In total, 53 patients (16 had available stored serum
samples) were treated with standard IFN-a 5 million
units 3× weekly plus oral ribavirin 1,200 mg daily for
24 weeks, and 125 were treated with pegylated-IFN-
a2a 180 mg plus daily weight-based ribavirin (1,000 mg
for body weight ≤75 kg and 1,200 mg for body weight
>75 kg) for 24 or 48 weeks based on the status of rapid
virological response (RVR). All patients were followed
for 24 weeks after discontinuation of treatment.
To study the chronological changes of serum IL-21
and ALT levels in CHC patients during IFN-based
therapy, 20 patients who had available stored serum
samples, virological data and serial serum ALT levels
were examined. Serum ALT levels before the first dos-
ing (week 0), every 4 weeks after the first dosing (week
4, 8, 12, 16 and 20), and every 24 weeks until the end of
follow-up were collected. Serum IL-21 levels at week 0,
week 4, week 12, end-of-treatment and 24 weeks after
cessation of the treatment were measured.
A total of 72 healthy controls negative for anti-HCV
were enrolled simultaneously from the database of
the Health Management Center in the Buddhist Tzu
Chi General Hospital, Taipei Branch (Taipei, Tai-
wan) between 2006 and 2007. We excluded subjects
positive for HBsAg, HIV or those with insufficient
information regarding HBsAg, anti-HCV and HIV.
Random selection without replacement was used to
ensure that no control subject was assigned to a group
to more than once.
The primary outcomes of interest were the asso-
ciation of IL-21R rs3093390 genotype with sustained
virological response (SVR) and differential serum IL-21
levels between CHC patients and non-HCV controls.
The study was conducted in accordance with the prin-
ciples of the Declaration of Helsinki, and approved by
the Ethical Committee of the National Taiwan Univer-
sity Hospital and Buddhist Tzu Chi General Hospi-
tal, Taipei Branch. All patients gave informed consent
before enrolment, and their viral parameters, and bio-
chemical, serological as well as anthropometric data
were recorded at enrolment.
Definitions of treatment response
The virological response to therapy was based on
serum HCV RNA levels. RVR was defined if an unde-
tectable serum HCV RNA level at day 28 was achieved.
Early virological response (EVR) was defined as unde-
tectable serum HCV RNA level or ≥2 log decrease of
the baseline HCV RNA level at week 12. Complete
EVR was defined as undetectable serum HCV RNA at
week 12 of therapy, and partial EVR as ≥2 log reduc-
tion of serum HCV RNA from baseline to week 12
of therapy. Virological response was defined as having
RVR or EVR. SVR were defined as having undetect-
able serum HCV RNA 24 weeks after cessation of the
Demographic pretreatment clinical features
Information on gender, age, body mass index (BMI),
complete blood count, serum aspartate aminotrans-
ferase (AST) and ALT levels were collected. BMI was
calculated as weight in kg divided by height in m2.
Blood samples were collected in the morning after 12 h
fasting and were measured by standard laboratory tech-
niques in both cohorts. Serum AST and ALT levels were
measured by an autoanalyser (Hitachi 7250 Special;
Hitachi, Tokyo, Japan) according to the manufacturer’s
IL-21/IL-21R genotypes and HCV treatment outcomes
Antiviral Therapy 18.4 601
instructions. ULN of serum ALT level was set at 30 U/l
for men and 19 U/l for women [28,29].
Serological markers and quantification of IL-21 and
HBsAg and anti-HCV were assayed with commercial
kits (Abbott Laboratories, North Chicago, IL, USA).
HCV viral load was determined by using the real-time
PCR-based single-tube assay as previously described
[30,31]. Serum IL-21 level was determined by an ELISA
assay (Human IL-21 Platinum ELISA Kit, eBiosci-
ence, Vienna, Austria) and serum IFN g-induced pro-
tein-10 (IP-10) level was determined by an ELISA assay
(Human IP-10 Instant ELISA Kit, eBioscience) accord-
ing to the manufacturer’s instructions.
Extraction, quantification and genotyping of HCV RNA
Serum RNA was extracted by using a commercial kit
(QIAamp RNA Blood Mini Kit; Qiagen Inc., Valencia,
CA, USA). Serum HCV RNA level was quantified by the
LightCycler (Roche Diagnostics Applied Science, Penz-
berg, Germany) with the detection limit of 86 copies/ml
(that is, 34 IU/ml) . Genotyping of HCV was per-
formed by the LightCycler PCR assay or reverse tran-
scription PCR with type-specific primers as previously
described [33,34]. The detection limit of the type-spe-
cific primers genotyping method is 100 copies/ml (that
is, 37 IU/ml). All samples were tested in triplicate.
Extraction of genomic DNA, rs3093390 and
All enrolled subjects were genotyped for SNPs
(rs3093390 and rs8099917). All blood specimens
were collected into EDTA tubes. Genomic DNA was
extracted by standard protocols with blood red blood
cell lysis, DNA binding, wash and elution. Extracted
DNA normalized to 50 ng/ml was obtained. DNA
quality was assessed by calculating the absorbance
ratio optical density 260 nm/280 nm using NanoDrop
model ND-1000 (Thermo Scientific, Wilmington, DE,
USA). The SNPs (rs3093390 and rs8099917) were
genotyped using the ABI TaqMan allelic discrimina-
tion kit and the ABI7900HT Sequence Detection Sys-
tem (Applied Biosystems, Foster City, CA, USA) .
Categorical data were presented as percentages and
continuous data were presented as means with stand-
ard deviations. Log transformation was performed
for variables with a significant deviation from nor-
mal distribution. A series of c2 tests, t-tests, and
Wilcoxon’s tests were used to analyse categorical,
parametric continuous and non-parametric varia-
bles, respectively. Linear regression and multivariate
analyses using logistic regression were performed to
examine the associations of serum IL-21 levels, SVR
and various clinical factors.
All analyses were performed with Stata statistical
software (version 8.0; Stata Corp., College Station, TX,
USA). All tests were two-sided and P<0.05 was consid-
ered statistically significant.
Baseline characteristics of subjects
A total of 250 subjects with available genomic DNA
were enrolled, including 178 patients with chronic
HCV genotype 1 infection and 72 non-HCV controls.
Among CHC patients, 128 (71.2%) patients attained
SVR, and 124 had available stored serum samples for
further cytokine analyses. The distributions of selected
demographic characteristics are shown in Table 1 and
Additional file 1. In brief, the selected demographic
characteristics were comparable between CHC patients
with and without stored serum samples. Patients in the
HCV group were predominantly male, had significantly
higher BMI and serum ALT level, but lower platelet
counts than the control group.
Association of IL-21R genotypes with virological
The frequencies of IL-21R and IL28B genotypes were
in Hardy-Weinberg equilibrium in the study population
(P=0.7693 for IL-21R genotype and P=0.8560 for IL28B
genotype). Although patients with rs8099917 TT geno-
type had higher RVR, EVR and SVR rates than those
with GT genotype (P<0.05), patients with rs3093390
CC genotype had comparable RVR, EVR and SVR
rates to those with CT or TT genotype (Table 2). How-
ever, among patients with rs8099917 GT genotype,
rs3093390 CC genotype was associated with a higher
SVR rate than CT or TT genotype (P=0.031; Table 2).
Further stratifying these analyses by the type of IFN did
not change the conclusions (data not shown).
Differential serum IL-21 levels between chronic
hepatitis C patients with and without sustained
In addition to the association of IL-21R genotype with
SVR, we further evaluated the roles of serum IL-21 and
IP-10 levels in predicting SVR among enrollers with
available stored serum samples. As chronic inflamma-
tion could modify serum cytokine levels and because
ALT was identified as a potential modifier in these
associations (Table 3), ALT-related effects were further
adjusted in our analyses.
Patients in the HCV group had higher mean ±sd
serum IL-21 levels (377.8 ±780.9 pg/ml) than the con-
trol group (70.5 ±33.2 pg/ml; Table 1). This difference
remained significant after adjustment for age, sex and
C-S Hsu et al.
©2013 International Medical Press602
HCV patients (n=124) Non-HCV controls (n=72)
Male sex, n (%)
Body mass index, kg/m2
Aspartate aminotransferase, U/l
Alanine aminotransferase, U/l
White blood cell count, k/ml
Platelet count, k/ml
rs3093390 CC genotype, n/total n (%)
rs8099917 TT genotype, n/total n (%)
HCV RNA, log10 IU/ml
HCV genotype 1, n (%)
PEG-IFN duration >24 weeks
Sustained virological response
Rapid virological response
Metavir fibrosis score
Table 1. Comparisons of demographic and metabolic characteristics between chronic hepatitis C patients and non-HCV controls
Data are displayed as mean (±sd) unless indicated otherwise. Histological data were evaluated semi-quantitatively using the Metavir scoring system. aThere were 92
chronic hepatitis C patients who had available data. bThere were 122 subjects who had available data. cThere were 94 subjects who had available data. cEVR, complete
early virological response; EVR, early virological response; IL, interleukin; IP-10, interferon g-induced protein-10; PEG-IFN, pegylated interferon; pEVR, partial early
Table 2. Associations of virological responses with IL-21R and IL28B genotype in 178 chronic hepatitis C patients
This table shows the associations of virological response and interleukin (IL)-21R and IL28B genotype. Use virological response (such as sustained virological response
[SVR], virological response [VR]) as the dependent variable, IL-21R (rs3093390) and IL28B (rs8099917) genotype as independent variables. aComparison of rs3093390 CC
versus CT/TT genotypes in patients with rs8099917 GG/GT genotype. bThere were 19 patients with IL28B non-TT genotypes who had available data. cEVR, complete early
virological response; EVR, early virological response; pEVR, partial early virological response; RVR, rapid virological response.
rs3093390 rs8099917 (rs8099917 GG/GT genotype) a
CC genotype CT/TT genotype CC genotype CT/TT genotype P-value TT genotype GT/GG genotype
IL-21/IL-21R genotypes and HCV treatment outcomes
Antiviral Therapy 18.4 603
ALT levels (P=0.013). Patients in the HCV group had
higher mean ±sd serum IP-10 levels (126.1 ±116.5
pg/ml) than the control group (88.3 ±12.1 pg/ml;
Table 1), and the difference remained significant after
adjustment for age, sex and ALT levels (P=0.021).
However, a higher pretreatment serum IL-21 level
(P=0.021), but not serum IP-10 level (P=0.315), was
a significant predictor for better virological responses
to IFN-based therapy after adjustment for age, sex,
BMI, viral loads, platelet counts, ALT levels and
IL28B genotype (Table 4).
Serial changes of serum IL-21 levels in chronic
hepatitis C patients receiving interferon-based therapy
As ALT may modify serum IL-21 level and its associa-
tion with virological response, we further examined the
chronological changes of serum IL-21 and ALT levels in
20 CHC patients receiving IFN-based therapy. Although
the changing patterns of serum IL-21 levels were com-
parable between patients with and without virologi-
cal responses, those without virological responses had
more frequent serum ALT elevations (>ULN of serum
ALT level) during week 4 to week 12 of IFN-based
therapy (virological responder versus non-virological
responder 4/33 versus 15/27; P=0.01; Figure 1).
Although previous studies addressed the important
role of IL-21 in controlling chronic HCV infections
[22–24] and implied a link between IL-21R and thera-
peutic response in CHC patients , the interactions
between IL-21 and chronic HCV infection remain
largely unclear. In this study, we demonstrated a
clinically useful role of IL-21R genotype in predict-
ing IFN-based therapeutic response in CHC patients
with unfavourable IL28B genotype. Moreover, we
found patients with chronic HCV infection had higher
serum IL-21 and IP-10 levels than healthy controls,
and identified a higher pretreatment serum IL-21 level
as a predictor for better virological responses to IFN-
based therapy. As identifying predictors for IFN-based
therapy is important in terms of clinical assessment
and management of CHC patients, our data not only
implied the predicting values of IL-21 level and IL-
21R genotype for HCV therapy, but also provided
a new viewpoint and helpful information to control
HCV infection. Of note, current existing evidence has
identified IL-21 as an essential component of CD4+
T-cells to specifically sustain CD8+ T-cell effector
activity during chronic viral infection , and IL-
21R signalling is required for the maintenance of poly-
functional T-cells . However, most of the data have
been derived from cell lines or animal models, and no
clinical data are available to support these concepts.
Clinical factors SVR (n=92) Non-SVR (n=32)
Male sex, n (%)
Body mass indexa, kg/m2
HCV RNA, log10 IU/mlb
Alanine aminotransferase, U/l
White blood cell count, k/mlc
Platelet count, k/mlc
rs8099917 TT genotype, n (%)c
Table 3. Comparisons of clinical characteristics between chronic hepatitis C patients with SVR and non-SVR
Data are displayed as mean (±sd) unless otherwise indicated. an=92. bn=94. cn=122. IP-10, interferon g-induced protein-10; SVR, sustained virological response.
Clinical factor OR (95% CI)
Male versus female sex
Body mass index, kg/m2
HCV RNA, log10 IU/ml
Alanine aminotransferase, U/l
Platelet count, k/ml
1.001 (0.93, 1.07)
2.71 (0.81, 9.13)
1.01 (0.81, 1.26)
0.23 (0.07, 0.80)
0.41 (0.19, 0.89)
0.998 (0.99, 1.004)
1.002 (0.99, 1.02)
0.19 (0.04, 0.87)
1.88 (0.55, 6.49)
Table 4. Factors associated with sustained virological
response identified by multivariate analyses in 76 chronic
hepatitis C patients
This table shows the associations of clinical factors and sustained virological
response (SVR). Use SVR as the dependent variable, and age in 1-year increments,
sex, body mass index, serum HCV RNA, alanine aminotransferase, platelet count,
rs8099917 genotype (IL28B single nucleotide polymorphism), interleukin (IL)-21
and interferon g-induced protein-10 (IP-10) level as independent variables. Serum
HCV RNA, IL-21 and IP-10 levels are log10 transformed. aGG/GT versus TT genotype
and GT/GT genotype =1.
C-S Hsu et al.
©2013 International Medical Press604
In this study, our data clearly demonstrated an asso-
ciation between higher serum IL-21 levels and better
IFN-based therapeutic responses in CHC patients. We
not only first address the link between chronic HCV
infection and IL-21/IL-21R signalling, but also further
consolidate these concepts in a clinical setting.
In our study, CHC patients had higher IL-21 levels
than non-HCV controls, and this finding confirmed
the previous concept that HCV may affect CD4+ and
CD8+ T-cells through the interaction with IL-21 and
IL-21R signalling [22–24]. Interestingly, we found an
elevated serum IL-21 level before IFN-based therapy
was usually followed by a decline of IL-21 during
treatment. However, the patterns of decline were
similar among patients with different therapeutic
response (that is, both patients with viral clearance
Case 17Case 13
Week 12Week 16 Week 20Week 24
Week 4Week 8
Week 12Week 16Week 20 Week 24
Case 1Case 4
Figure 1. Chronological changes of serum IL-21 and alanine aminotransferase levels in chronic hepatitis C patients receiving
All patients were followed for 24 weeks after discontinuation of treatment. (A) Changes in serum interleukin (IL)-21 levels in 9 chronic hepatitis C (CHC) patients
without virological response during interferon therapy. Most of their serum IL-21 levels decreased during interferon therapy. (B) Changes in serum IL-21 levels in 11
CHC patients with virological response during interferon therapy. All of their serum IL-21 levels decreased during interferon therapy. (C) Changes in serum alanine
aminotransferase (ALT) levels in 9 CHC patients without virological response during interferon therapy. Most of their serum ALT were elevated (>40 U/l) during
interferon therapy. (D) Changes in serum ALT levels in 11 CHC patients with virological response during interferon therapy. Except case 10 and 16, most of their serum
ALT levels were within a normal range (ALT≤40 U/l) during interferon therapy. Both cases 10 and 16 achieved sustained virological response, while case 10 had elevated
ALT levels at weeks 24 and 48, and case 16 had elevated levels during weeks 20 to 72. During weeks 4 to 12 of interferon-based therapy, there were 33 observations for
the serum ALT levels of patients with virological response and 27 for those with non-virological response. Patients without virological response had significantly more
frequent serum ALT elevation during week 4 to week 12 of interferon-based therapy (virological responder versus non-virological responder 4/33 versus 15/27; P=0.01).
EOF, end of follow-up; EOT, end of treatment.
IL-21/IL-21R genotypes and HCV treatment outcomes
Antiviral Therapy 18.4 605
and persistent viraemia have similar serum IL-21
decline patterns). Although it is speculated that an
increasing IL-21 level may be induced by the immu-
nological response of CD4+ T-cells to HCV infec-
tion and a higher serum IL-21 level may represent a
more severe infection, the dissociation between IL-21
decline and therapeutic response suggests the possible
existence of other factors blocking IL-21 production
by CD4+ T-cells in patients with persistent viraemia
and poor response to interferon. Future studies are
needed to clarify this important and interesting issue.
Our study had some limitations. First, this retro-
spective study was a case-control design, and hence
only associations between chronic HCV infection and
IL-21/IL-21R could be determined. Future studies with
a longitudinal design, more follow-up data and paired
controls are required to explore the effect of disease
stages (such as fibrosis, cirrhosis or hepatocellular car-
cinoma) on the association of IL-21/IL-21R with HCV
infection, and elucidate possible causal relationships.
Second, although IP-10 may have predicted virologi-
cal response and SVR in previous studies [35,36], its
predicting value in this study was only demonstrated
in univariate analyses and IL-21 outweighed IP-10 in
predicting SVR when adjusting for known prognostic
factors. Third, our data echoed a previous study, which
has linked ALT elevation in the later phases of IFN
therapy (between week 12 to the end of treatment) to a
higher chance of relapse . Moreover, we found that
frequent ALT elevations between week 4 and week 12
also predicted a poor virological response. This find-
ing may be helpful for clinicians to predict therapeutic
response at an earlier stage. Last, there remains insuf-
ficient data indicating that rs3093390 may be a poten-
tial functional variant. Therefore, further studies to
identify the relevant functional variants, or additional
SNP discovery and validation efforts, are needed.
In summary, IL-21R genotype and pretreat-
ment serum IL-21 level can help predict therapeutic
response in CHC patients receiving IFN-based treat-
ment. Patients with IL-21R CC genotype and higher
pretreatment serum IL-21 level may have a better
virological response, but elevated ALT levels during
IFN-based therapy are associated with a poor virologi-
cal response. Whether these findings are attributed to
the complex immunological effects of IL-21 in CHC
patients awaits further studies.
We thank colleagues in the National Taiwan University
Hospital and its Yun-Lin Branch, who helped enrol and
follow-up patients, and research assistants who con-
tributed to laboratory analyses and collected clinical
information. We also thank colleagues in the Buddhist
Tzu Chi General Hospital, Taipei Branch, for enrolling
and following-up the study subjects.
This work was supported in part by grants from
the National Taiwan University Hospital, the Bud-
dhist Tzu Chi General Hospital, Taipei Branch, the
Department of Health, and the National Science Coun-
cil, Executive Yuan, Taiwan (TCRD-TPE-100-C1-2,
C-SH planned and conducted this project, analysed
data, conducted interpretation of data, and wrote
this paper. S-JH helped in acquisition of data. W-LL
helped in analysing and interpretation of data. C-LC
helped in statistical analysis and interpretation of
data. C-JL, P-JC and D-SC helped in critical revision
of the manuscript for important intellectual content.
J-HK supervised this study, obtained funding, planned
this project, interpreted results and wrote this paper.
P-JC is a consultant for Novartis, Roche and Gilead
Sciences. D-SC is a consultant for Bristol–Myers
Squibb, Novartis, GlaxoSmithKline, Roche and
Merck Sharp & Dohme. J-HK is a consultant for
Abbott, Bristol–Myers Squibb, Gilead Sciences, Glax-
oSmithKline, Merck Sharp & Dohme, Novartis and
Roche and is on the speaker’s bureau for Abbott,
Roche, Bayer, Bristol–Myers Squibb, GlaxoSmith-
Kline and Novartis. All other authors declare no com-
Additional file 1: A table displaying demographic char-
acteristics of 178 CHC patients can be accessed via
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Accepted 15 November 2012; published online 7 January 2013