Niimura 1990.

Study characteristics
Methods	This study was carried out in a secondary care setting. This study was blinded. Intention‐to‐treat analysis was not carried out. This was a left‐right study. This study was conducted in Japan.
Participants	80 participants were recruited: 16 dropped out. Inclusion criteria of the trial Adults and children Ordinary or refractory warts not specified Warts on the hands or feet
Interventions	Intralesional injection of IFN‐beta (0.1 mls of 1 millionU/ml weekly) Placebo (saline injection) Therapy continued until 1 extremity had cleared or the participant had received 10 weekly injections.
Outcomes	Outcomes of the trial Cure at 10 weeks
Notes	1 wart per participant was injected.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	It was unclear if true randomisation occurred. No further details were available about the method of randomisation.
Allocation concealment (selection bias)	Unclear risk	This was unclear.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote (page 1495): "(Identical) vials were labelled A or B by a controller who maintained the code until the experiment was completed." Comment: This was probably done.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	This was unclear (stated to be 'double blind').
Incomplete outcome data (attrition bias) All outcomes	High risk	16/80 participants left the study; no reasons were given. The numbers of dropouts by intervention group were not given.
Selective reporting (reporting bias)	Low risk	All outcomes were reported.