This review assessed hepatitis C treatment outcomes, compliance and completion rates among injecting drug users and concluded that injecting drug users can be successfully treated for both chronic and acute hepatitis. Given the potential for missed studies, poor reporting of review methods and included studies of unknown quality, this finding should be interpreted with caution.

To assess hepatitis C treatment outcomes, compliance and completion rates among injecting drug users (IDUs) and rates of re-infection after treatment.

PubMed and Web of Science were searched for English-language studies to September 2008; search terms were reported. Reference lists of included studies were searched for additional articles.

Studies that assessed hepatitis C treatment among injecting drug users were eligible for inclusion if rates of sustained virological response (SVR) treatment completion and/or compliance for injecting drug users could be identified. SVR was defined as a patient being hepatitis C RNA (ribonucleic acid) negative 24 weeks after treatment completion. Also eligible were studies that investigated injecting drug user status as a secondary analysis.

Study design and definitions of injecting drug users varied between included studies. Interventions were: interferon (IFN), ribavirin (RBV) and pegylated IFN; these were assessed alone (IFN) or in combination. Just under half of the studies compared results from injecting drug users with those of a group of non-injecting drug users; the rest recruited injecting drug users only. Studies were in former, current and in-treatment injecting drug users with acute or chronic hepatitis C.

The authors stated neither how the studies were selected for the review nor how many reviewers were involved in the selection process.

The authors did not state that they assessed study validity.

The authors stated neither how the data were extracted for the review nor how many reviewers performed the data extraction.

The studies were combined in a narrative synthesis.

A total of 22 studies (n=3,121, range 12 to 792) were included in the review.

In trials that prescribed pegylated interferon plus ribavirin, the median rate of SVR among injecting drug users was 54.3% (range 18.1% to 94.1%; nine studies). When all chronic hepatitis C trials that included injecting drug users were combined, regardless of treatment regimen, the median rate of SVR among injecting drug users was 40.6% (range 15.8% to 94.1%). No studies that included non-injecting drug user comparison groups reported a statistically significant difference between rate of SVR among injecting drug users and non-injecting drug users.

Among individuals in whom treatment was initiated for acute hepatitis C, SVR was 68.5% for 89 injecting drug users versus 81.5% for 65 non-injecting drug users (seven studies). For groups of injecting drug users who were enrolled in drug treatment programs prior to the initiation of hepatitis C treatment, median SVR rate was 47.6% (range 27.6% to 94.1%%; 13 studies)

Injecting drug users can be successfully treated for both chronic and acute hepatitis.

The review question was clear and inclusion criteria were broadly defined in terms of intervention, outcomes, participants and study design. The literature search was of limited scope and was restricted to publications in English, which meant that language bias could have been present. No apparent attempt was made to locate unpublished studies; therefore, some studies may have been missed. No attempts were made to minimise reviewer error and bias for any stage of the review process. No assessment of the methodological quality of the included studies was reported; this made it difficult to assess reliability of the included data. A narrative synthesis was appropriate given the differences between trials in terms of trial recruitment and treatment regimens. The authors' interpretation of the data presented was reasonable, but given the potential for missed studies, poor reporting of review methods, included studies of unknown quality and variability in outcomes between studies, should be interpreted with caution.

Practice: The authors did not state any implications for practice.

Research: The authors stated that additional studies were required to assess how to select patients who could be treated successfully for hepatitis C and determine the optimum timing for treatment and the minimum duration of drug abstinence. Further research was required to assess which factors impacted upon treatment compliance and outcomes.

Not stated.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.