Interferon-?? Alone versus Interferon-?? plus Ribavirin in Patients with Chronic Hepatitis C Not Responding to Previous Interferon-?? Treatment

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.

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.

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.

Treatment of chronic hepatitis C: a systematic review

This systematic review addressed 3 issues regarding current treatments for chronic hepatitis C: (1) efficacy and safety in treatment-naive patients; (2) efficacy and safety in selected subgroups of patients; and (3) effects on long-term clinical outcomes. Electronic databases were searched for articles from January 1996 to March 2002. Additional articles were identified by searching references in pertinent articles and recent journals and by questioning experts. Articles were eligible for review if they reported original human data from a study that used virological, histological, or clinical outcome measures. For data collection, paired reviewers assessed the quality of each study and abstracted data. This systematic review found that the combination of high-dose peginterferon and ribavirin was more efficacious than standard interferon and ribavirin in persons infected with hepatitis C virus (HCV) genotype 1 (sustained virologic response [SVR] rate: 42% vs. 33%) and that ranges of SVR rates were higher with peginterferon than standard interferon monotherapy in naïve patients (10% to 39% vs. 3% to 19%). Reports were consistent in showing treatment with interferon and ribavirin was more efficacious than interferon monotherapy in treatment-naive persons and previous nonresponders and relapsers. Studies were moderately consistent in showing that treatment decreases the risk for hepatocellular carcinoma (HCC). The evidence on treatment in important subgroups was limited by a lack of randomized controlled trials. Thus, the combination of peginterferon and ribavirin was the most efficacious treatment in patients with HCV genotype 1. Long-term outcomes were improved in patients with hepatitis C who achieved an SVR with treatment.

Treatment of chronic hepatitis C: a systematic review

This systematic review addressed 3 issues regarding current treatments for chronic hepatitis C: (1) efficacy and safety in treatment-naive patients; (2) efficacy and safety in selected subgroups of patients; and (3) effects on long-term clinical outcomes. Electronic databases were searched for articles from January 1996 to March 2002. Additional articles were identified by searching references in pertinent articles and recent journals and by questioning experts. Articles were eligible for review if they reported original human data from a study that used virological, histological, or clinical outcome measures. For data collection, paired reviewers assessed the quality of each study and abstracted data. This systematic review found that the combination of high-dose peginterferon and ribavirin was more efficacious than standard interferon and ribavirin in persons infected with hepatitis C virus (HCV) genotype 1 (sustained virologic response [SVR] rate: 42% vs. 33%) and that ranges of SVR rates were higher with peginterferon than standard interferon monotherapy in naïve patients (10% to 39% vs. 3% to 19%). Reports were consistent in showing treatment with interferon and ribavirin was more efficacious than interferon monotherapy in treatment-naive persons and previous nonresponders and relapsers. Studies were moderately consistent in showing that treatment decreases the risk for hepatocellular carcinoma (HCC). The evidence on treatment in important subgroups was limited by a lack of randomized controlled trials. Thus, the combination of peginterferon and ribavirin was the most efficacious treatment in patients with HCV genotype 1. Long-term outcomes were improved in patients with hepatitis C who achieved an SVR with treatment.