Two RCTs (n=2,651) investigated combination therapy and four RCTs (n=2,180) investigated monotherapy.
The trials were generally of a good quality, although their methodological details were not always thoroughly reported.
Combination therapy (2 RCTs).
The combined percentage of sustained virological response was 55% (95% CI: 52, 58) using pegylated IFN and 46% (95% CI: 43, 49) using non-pegylated IFN. The relative risk (RR) for remaining infected was reduced for pegylated in comparison with non-pegylated IFN (RR 0.83, 95% CI: 0.76, 0.91). There was no evidence of statistical heterogeneity (P=0.29; I-squared 12%).
Monotherapy (4 RCTs).
The combined percentage of sustained virological response was 31% (95% CI: 27, 34) for pegylated IFN and 14% (95% CI: 12, 17) for non-pegylated IFN. The RR for remaining infected was reduced for pegylated in comparison with non-pegylated IFN (RR 0.80, 95% CI: 0.76, 0.85). There was evidence of statistical heterogeneity (P=0.03; I-squared 66.6%).
For both combination and monotherapy, treatment response varied according to viral genotype and other prognostic variables, including baseline viral load. Adverse events with pegylated IFN were not substantially different from the rates of adverse events observed with non-pegylated IFN.