Gustafsson 2004.

Study characteristics
Methods	This study was carried out in a secondary care setting. This study was blinded. Intention‐to‐treat analysis was not applicable. This study was conducted in Sweden.
Participants	40 participants were recruited: None dropped out. Inclusion criteria of the trial Adults and children Refractory warts Warts on the hands or feet
Interventions	α‐lactalbumin‐oleic acid in saline (1 drop per lesion) Placebo (saline) Applied once a day for 3 weeks.
Outcomes	Outcomes of the trial > 75% reduction in wart volume at 2 months
Notes	The trial converted to open‐label after the first 3 months.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	This was described as randomised, and a randomisation code was mentioned, but no further details were given.
Allocation concealment (selection bias)	Unclear risk	No details were given.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Bottles of the intervention were coded, but no further details were given.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote (page 2665): "The randomisation code was broken one month after all patients had completed three weeks of the randomly assigned treatment." Comment: This was probably adequate.
Incomplete outcome data (attrition bias) All outcomes	Low risk	40 participants entered the trial; 34 were available for follow up at the end of the trial. There were no withdrawals from the first phase of the study. There were 2/40 withdrawals from the second phase – who were lost to follow up (LFU) (1 from each of the original 2 groups). No reasons were given for dropouts. Comment: This was unlikely to introduce a high risk of risk of bias.
Selective reporting (reporting bias)	Low risk	All outcomes (lesion volume and number of lesions) were reported.