Omata 1991

Methods	Randomised clinical trial.
Participants	Country: Japan. Number randomised: 27. Post‐randomisation dropouts: 2 (7.4%). Revised sample size: 25. Mean age: 40 years. Females: 14 (56%). Genotype 1: not stated. Genotype 3: not stated. Other genotypes: not stated. Mean follow‐up period in months (for all groups): 36. Inclusion criteria Serum ALT > 200 IU after transfusion or raised serum ALT without a history of taking hepatotoxic drug or of heavy alcohol intake. Seronegativity for hepatitis B surface antigen, IgM antibody to HBV core protein, IgM‐HA antibody, HBV‐DNA, and autoimmune markers. Liver histology compatible with the diagnosis of acute hepatitis.
Interventions	Participants were randomly assigned to 2 groups. Group 1: interferon‐beta (n = 11). Further details: interferon‐beta, 3 MU IV for 5 consecutive days in the first week, and then 3 times per week for the next 3 weeks. Group 2: no treatment (n = 14). Duration of treatment: 1 month.
Outcomes	Sustained virological response.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "25 patients with acute non‐A, non‐B hepatitis drew lots for allocation to treatment with interferon."
Allocation concealment (selection bias)	Low risk	Quote: "25 patients with acute non‐A, non‐B hepatitis drew lots for allocation to treatment with interferon."
Blinding of participants and personnel (performance bias) All outcomes	High risk	Comment: placebo not used.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: information not available.
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: "2 patients in the untreated group were lost to follow‐up." Comment: there were post‐randomisation dropouts.
Selective reporting (reporting bias)	High risk	Comment: some important outcomes which would generally be assessed were not reported.
For‐profit bias	Unclear risk	Comment: this information was not available.
Other bias	Low risk	Comment: there was no other bias.