Brooker 1992.

Methods	Randomised controlled trial (ears)
Participants	Unilateral or bilateral OME diagnosed by otoscopy, audiometry and tympanometry 40 children Aged 3 to 10 referred to ENT
Interventions	Carnival balloon 3 times a day or no treatment for 3 weeks Both groups had equal care except for the intervention
Outcomes	Pure‐tone audiometry Tympanometry (Both at 3 weeks) Parents reported "good compliance"
Notes	Ears Children unable to use the carnival blower excluded prior to randomisation
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation by selection of envelopes (e‐mail confirmation from author 13 November 2012)
Allocation concealment (selection bias)	Unclear risk	Sealed envelopes
Comparability of groups at pre‐test	Unclear risk	Not stated
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	No attrition; 100% follow‐up
Selective reporting (reporting bias)	Low risk	No evidence of selective reporting