Studies of monotherapy with conventional or pegylated interferon in patients on maintenance haemodialysis, peritoneal dialysis, or with chronic renal failure not yet requiring dialysis, were eligible for inclusion. Eligible studies had to report the primary outcome of sustained virological response (defined as disappearance of hepatitis C virus viraemia by polymerase chain reaction at least six months after completion of therapy). Studies were excluded if they: reported inadequate data on measures of response; included patients with co-existing diseases; involved patients who had been previously treated, not responded to treatment, relapsed or renal transplant recipients; used methods other than polymerase chain reaction (PCR) to report viral response rates.
Secondary outcomes included drop-out rate as a proxy for tolerability, end-of-treatment virological response, end-of-treatment biochemical response, and sustained biochemical response.
Interferon was administered subcutaneously in most studies. Where reported, mean time on dialysis prior to initiation of treatment ranged from 36 to 122 months; most participants were non-cirrhotic with hepatitis C virus genotype 1. The mean age of the participants ranged from 31.9 to 54 years; between 31% and 91.7% were male. Most of the studies were conducted across centres in western Europe. The treatment duration was 24 or 48 months in most studies.
At least two reviewers appeared to independently select studies for inclusion in the review.
The authors excluded four studies of pegylated interferon 'because of limited size (n≤ nine)', but they included two studies of conventional interferon with sample sizes of nine.