Interferon-alpha2b induction treatment with or without ribavirin in chronic hepatitis C: a multicenter, randomized, controlled trial

A statistical method for removing unbalanced trials with multiple covariates in meta-analysis

In meta-analysis literature, there are several checklists describing the procedures necessary to evaluate studies from a qualitative point of view, whereas preliminary quantitative and statistical investigations on the "combinability" of trials have been neglected. Covariate balance is an important prerequisite to conduct meta-analysis. We propose a method to identify unbalanced trials with respect to a set of covariates, in presence of covariate imbalance, namely when the randomized controlled trials generate a meta-sample that cannot satisfy the requisite of randomization/combinability in meta-analysis. The method is able to identify the unbalanced trials, through four stages aimed at achieving combinability. The studies responsible for the imbalance are identified, and then they can be eliminated. The proposed procedure is simple and relies on the combined Anderson-Darling test applied to the Empirical Cumulative Distribution Functions of both experimental and control meta-arms. To illustrate the method in practice, two datasets from well-known meta-analyses in the literature are used.

Host Cell Targets in HCV Therapy: Novel Strategy or Proven Practice?

The development of novel antiviral drugs against hepatitis C is a challenging and competitive area of research. Progress of this research has been hampered due to the quasispecies nature of the hepatitis C virus, the absence of cellular infection models and the lack of easily accessible and highly representative animal models. The current combination therapy consisting of interferon-α and ribavirin mainly acts by supporting host cell defence. These therapeutics are the prototypic representatives of indirect antiviral agents as they act on cellular targets. However, the therapy is not a cure, when considered from the long-term perspective, for almost half of the chronically infected patients. This draws attention to the urgent need for more efficient treatments. Novel anti-hepatitis C treatments under study are directed against a number of so-called direct antiviral targets such as polymerases and proteases, which are encoded by the virus. Although such direct antiviral approaches have proven to be successful in several viral indications, there is a risk of resistant viruses developing. In order to avoid resistance, the development of indirect antiviral compounds has to be intensified. These act on host cell targets either by boosting the immune response or by blocking the virus host cell interaction. A particularly interesting approach is the development of inhibitors that interfere with signal transduction, such as protein kinase inhibitors. The purpose of this review is to stress the importance of developing indirect antiviral agents that act on host cell targets. In doing so, a large source of potential targets and mechanisms can be exploited, thus increasing the likelihood of success. Ultimately, combination therapies consisting of drugs against direct and indirect viral targets will most probably provide the solution to fighting and eradicating hepatitis C virus in patients.

Features of hepatitis C virus infection, current therapies and ongoing clinical trials in ten Asian Pacific countries

Estimated hepatitis C virus (HCV) infection rates in the general populations were 1.3, 0.9, 0.4-1.0, 14.7, 0.1-0.3, 0.9-1.9, 1.0-2.0, 5, 4.4-8.6 and 0.5-1.3 % in Australia, Bangladesh, Mainland China, Egypt, Hong Kong, India, Japan, Pakistan, Taiwan and Turkey, respectively. The main HCV genotypes (Gs) are G1, G3, G1b, G4, G1b, G3, G1b, G3, G1b and G2, and G1 in Australia, Bangladesh, Mainland China, Egypt, Hong Kong, India, Japan, Pakistan, Taiwan and Turkey, respectively. Of IL28B genotypes, favorable alleles are ~50 % in Australia and Turkey, but 60-70 % in most of the other Asian countries. Peginterferon plus ribavirin is available in all ten Asian Pasific countries. In addition, HCV NS3/4A protease inhibitors with peginterferon plus ribavirin are currently available in several countries. Clinical trials of interferon-free regimens for HCV are ongoing in most of the ten Asian Pacific countries.

Ribavirin plus interferon versus interferon for chronic hepatitis C

BACKGROUND

Hepatitis C is a major cause of liver-related morbidity and mortality. Standard therapy is ribavirin plus pegylated interferon to achieve undetectable level of virus in the blood, but the effect on clinical outcomes is controversial.

OBJECTIVES

To assess the beneficial and harmful effects of ribavirin and interferon combination therapy versus interferon monotherapy for chronic hepatitis C.

SEARCH STRATEGY

We identified trials through electronic databases, manual searches of bibliographies and journals, approaching authors of trials, and pharmaceutical companies until March 2009.

SELECTION CRITERIA

We included randomised trials, irrespective of blinding, language, or publication status, comparing ribavirin plus interferon versus interferon for treatment of chronic hepatitis C.

DATA COLLECTION AND ANALYSIS

The primary outcome measures were serum sustained loss of hepatitis C virus, liver-related morbidity plus all-cause mortality, and adverse events. We performed subgroup analyses of patients who were naive, relapsers, or non-responders to previous antiviral treatment. All outcomes were analysed with the random-effects model. We used Peto odds ratios (OR) with 95% confidence intervals (CI) for analysis of morbidity plus mortality. The remaining outcomes were presented as relative risks (RR). We used trial sequential analyses to examine the robustness of our findings.

MAIN RESULTS

We included 83 randomised trials with 12,707 patients. Most trials had unclear or high risk of bias. We did not find any significant influence of bias on our results but cannot exclude outcome measure reporting bias as many trials did not report on the primary outcomes of this review. Compared with interferon, ribavirin plus interferon had a significant beneficial effect on sustained virological response in subgroups of naive patients (RR 0.72, 95% confidence interval (CI) 0.68 to 0.75), relapsers (RR 0.62, 95% CI 0.54 to 0.70), non-responders (RR 0.89, 95% CI 0.84 to 0.93), and in all patients (RR 0.75, 95% CI 0.71 to 0.79). Combination therapy significantly reduced morbidity plus mortality in all patients (Peto OR, 0.43, 95% CI 0.23 to 0.79), but not in naive, relapsers, or non-responders individually. Combination therapy significantly increased the risk of haematological, dermatological, gastrointestinal, infectious, and miscellaneous (cough, dyspnoea, fatigue) adverse reactions. Accordingly, combination therapy significantly increased the risk of treatment discontinuation and dose reductions. Trial sequential analyses confirmed our findings regarding virological effects, but not regarding liver-related morbidity and all-cause mortality.

AUTHORS' CONCLUSIONS

Compared with interferon alone, ribavirin plus interferon is more effective in clearing hepatitis C virus from the blood. Combination therapy may reduce liver-related morbidity and all-cause mortality, but we need more evidence. The number needed to treat to obtain a beneficial effect is considerable considering the increased risk of several severe adverse reactions and costs.

Combination Therapy of Interferon and Ribavirin Versus Interferon Monotherapy in Treatment of Chronic Hepatitis C: A Meta-analysis of Clinical Trials

This meta-analysis was conducted to assess the efficacy and safety of interferon and ribavirin combination therapy (CT) versus interferon monotherapy (IMT) in inducing sustained response in interferon-naïve, relapser, and nonresponder chronic hepatitis C patients. A literature search was performed using the MEDLINE database for clinical trials published in the period between 1995 and 2003. A total of 31 randomized trials and 7 nonrandomized trials comparing CT with interferon alone or comparing different dose regimens of CT were included in this meta-analysis. The primary outcome measure was sustained virological response. The summary estimate of the odds ratio was obtained using the random effect model. The study showed that sustained virological response rate was significantly higher in interferon-naïve, relapser, and nonrespondent chronic hepatitis C patients who were on CT compared to IMT (odds ratio = 3.23, 17.65, and 4.71, respectively). There was no statistically significant difference in virological and biochemical responses between different dose regimens of CT. Side effects, dose reduction, and treatment discontinuation rates were significantly higher in patients receiving CT compared with IMT. Treatment with interferon plus ribavirin has a significant benefit on the virological and biochemical response in patients with chronic hepatitis C irrespective to the previous treatment, and it should be considered the treatment of choice in naïve, relapser, and nonrespondent chronic hepatitis C patients.

Treatment of hepatitis C infection

HCV infection is one of the leading causes of chronic liver disease worldwide,and it results in cirrhosis, liver failure, and HCC. As a result, hepatitis C cirrhosis has become the principal indication for liver transplantation. Ironically,HCV infection can be cured with available antiviral therapies, but only a minority of infected persons has ever been treated. The current standard of therapy isa combination of PEG-IFNalpha and ribavirin, which produces high rates of SVRs(absence of detectable HCV RNA at least 24 weeks after cessation of therapy):42% to 56% in genotype 1 and 75% to 84% in genotypes 2 and 3. Recent reports indicate that the less frequent genotypes 4, 5, and 6 also are responsive to combination therapy. Recommendations for treatment of conventional and special patient populations were reviewed in detail. Newer therapeutics that are entering clinical trials provide hope that SVRs may be possible in patients who are difficult to treat and in nonresponders to current therapy.

Ribavirin plus interferon versus interferon for chronic hepatitis C

BACKGROUND

Hepatitis C is a major cause of liver-related morbidity and mortality. The disease progresses without symptoms for several decades and most patients are diagnosed based on the presence of hepatitis C virus ribonucleic acid and elevated transaminases.

OBJECTIVES

To assess the beneficial and harmful effects of ribavirin and interferon combination therapy versus interferon monotherapy for chronic hepatitis C.

SEARCH STRATEGY

We identified trials through electronic databases, manual searches of bibliographies and journals, approaching authors of trials and pharmaceutical companies, until May 2004.

SELECTION CRITERIA

We included randomised trials, irrespective of blinding, language, or publication status, comparing ribavirin plus interferon versus interferon alone for treatment of chronic hepatitis C.

DATA COLLECTION AND ANALYSIS

The primary outcome measures were the sustained loss of hepatitis C virus and liver-related morbidity plus all-cause mortality. We separately analysed patients who were naive, relapsers, or non-responders to previous antiviral treatment. Random-effects and fixed-effect model meta-analyses were performed for all outcomes. We used Peto odds ratios (OR) with 95% confidence intervals (CI) for analysis of morbidity plus mortality. The remaining outcomes were presented as relative risks (RR).

MAIN RESULTS

We included 72 randomised trials with 9991 patients. Most trials had low methodological quality but we did not find any significant influence of quality on our results. Compared with interferon, combination therapy had a significant beneficial effect on sustained virological response (RR 0.73, 95% CI 0.71 to 0.75) and in subgroups of naive patients (RR 0.72, 95% CI 0.68 to 0.76), relapsers (RR 0.63, 95% CI 0.54 to 0.73), and non-responders (RR 0.89, 95% CI 0.84 to 0.94) individually. Combination therapy significantly reduced morbidity plus mortality (Peto OR 0.46, 95% CI 0.22 to 0.96), but not in naive, relapsers, or non-responders individually. Combination therapy also had a significant beneficial effect on the histological response. Combination therapy significantly increased the risk of anaemia (RR 10.48, 95% CI 5.34 to 20.55), which occurred in 22% of patients on combination therapy. Combination therapy also significantly increased the risk of dermatological, gastrointestinal, infectious, and miscellaneous (cough, dyspnea, fatigue) adverse events. Accordingly, combination therapy significantly increased the risk of treatment discontinuation (RR 1.19, 95% CI 1.01 to 1.39).

AUTHORS' CONCLUSIONS

Compared with interferon alone, ribavirin plus interferon is more effective in clearing hepatitis C virus and improving liver histology. This may lead to reduced morbidity and mortality. However, combination therapy significantly increased the risk of several adverse events.