Thirty-three studies (n=770 patients) were included in the review. Twenty-one studies (n=491 patients) assessed interferon-alpha 2a or 2b, and 12 studies (n=279 patients) assessed pegylated interferon-alpha 2a or 2b. Two studies were RCTs, the rest were described as retrospective evaluations (two studies), clinical trials (19 studies) or controlled clinical trials (eight studies).
Overall, 266 patients (44.5%) attained a sustained viral response and 174 patients (22.7%) discontinued treatment due to adverse events.
The rate of sustained viral response in standard interferon groups was 39.1% (95% CI 32.1 to 46.1), while in pegylated interferon the response was 39.3% (95% CI 26.5 to 52.1). The rates of treatment discontinuation were 22.6% (95% CI 10.4 to 34.8) for standard interferon and 29.7% (95% CI 21.7 to 37.7) for pegylated interferon.
The only variable that was significantly associated with sustained viral response was an age less than 40 years (OR 2.17, 95% CI 1.03 to 4.50). Treatment duration (24 weeks versus 48 weeks) was not associated with a statistically significant difference in response.
There was no evidence of publication bias.