Kattipattanapong 2013.

Study characteristics
Methods	RCT
Participants	133 adults who underwent ear surgery with a post‐auricular approach in Thailand between May 2010 and May 2011
Interventions	Group 1: hair removal with razor (n = 66) Group 2: no hair removal (n = 70) Product details: a razor was used with a dry shave. Timing of hair removal: not reported. Hair removed by: not reported. Venue for hair removal: not reported.
Outcomes	Primary outcome: SSIs as defined by CDC criteria. SSIs within 30 days were recorded, but no details provided as to when they were assessed or by whom. Secondary outcome: factors associated with SSI ‐ demographic data.
Notes	Competing interests: none. Sponsorship: none. Funding sources: none
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "block randomization using random allocation software" Comment: consider adequate approach.
Allocation concealment (selection bias)	Unclear risk	Not reported. Comment: not clear whether the person responsible for allocation to groups would have been able to predict to which group a potential participant would be allocated.
Blinding (performance bias and detection bias) Care providers blinded	Unclear risk	Not reported. Comment: unclear whether care providers were blinded to intervention allocation.
Blinding (performance bias and detection bias) Participants blinded	High risk	Not reported. Comment: participants would have been aware of hair removal method.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported. Comment: unclear whether assessors were blinded to intervention allocation.
Incomplete outcome data (attrition bias) ITT analysis undertaken	Unclear risk	Not reported. Comment: no discussion of whether participants were analysed in the groups to which they had been allocated.
Incomplete outcome data (attrition bias) Drop out rate acceptable	Low risk	Participants who dropped out are accounted for, and participants were distributed evenly across groups. Comment: the number of dropouts was judged to be unlikely to have altered the result, even in a worst‐case scenario (i.e. assuming that those that dropped out developed an SSI).
Selective reporting (reporting bias)	Low risk	Main outcomes reported. Comment: unlikely to be affected by reporting bias.
Other bias	Low risk	Comment: participant groups were equal or similar.