Larsen 1996.

Study characteristics
Methods	This study was carried out in a secondary care setting; it was multicentre; and it was open. Intention‐to‐treat analysis was carried out. This study was conducted in Denmark.
Participants	185 participants were recruited: 41 dropped out. Inclusion criteria of the trial Adults and children Ordinary warts Warts on the hands
Interventions	Cotton wool bud cryotherapy ‐ 2‐weekly intervals versus 3‐weekly intervals versus 4‐weekly intervals between freezes Treatment continued until wart resolution or a maximum of 6 freezes had been applied.
Outcomes	Outcomes of the trial Cure at 6 months
Notes	The study was done on 1 index wart per participant only.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A table of random numbers was used ('Materials and methods', page 29).
Allocation concealment (selection bias)	Unclear risk	This was unclear; no details were given.
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding was attempted (an open trial).
Blinding of outcome assessment (detection bias) All outcomes	High risk	No blinding was attempted (an open trial).
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Reasons for attrition were given. Quote (page 29): "There were no significant differences in the age, sex, duration of disease or number of warts among the patients who left the study and the 144 (of 185) patients who completed the treatment schedule." It was unclear how the dropouts were distributed across the treatment groups.
Selective reporting (reporting bias)	Unclear risk	Quote (page 29): "For some patients not all the information on treatment results was available 3 and 6 months after initiation of treatment."