Lee 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 Korea.
Participants	74 participants were recruited: The number of dropouts was unclear. Inclusion criteria of the trial Adults and children Refractory warts Warts on the hands or feet
Interventions	IFN‐gamma: high‐dose (5 millionU/ml) versus Low‐dose (1 millionU/ml) versus Placebo Intralesional injections were given twice‐weekly for 3 weeks.
Outcomes	Outcomes of the trial Cure at 4 weeks
Notes	The numbers of withdrawals and dropouts were not clear from the text. The placebo group (group C) consisted of participants with multiple warts; therefore, they may not be valid.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote (page 78): "...randomly divided in to two groups." No details were given. The method was not stated. Also, there was a large discrepancy between the numbers in each group: group A (n = 36), group B (n = 53). Therefore, this was not appropriately randomised.
Allocation concealment (selection bias)	Unclear risk	This was unclear; no details were given.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	It was unclear if blinding was attempted.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	It was unclear if blinding was attempted.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	It was unclear how many participants out of 74 dropped out; there were no details. Comment: This was judged as high risk because of lack of information.
Selective reporting (reporting bias)	Low risk	All outcomes were reported.