Blanshard 1993.

Methods	Randomised controlled trial
Participants	Bilateral OME on tympanometry 85 children 3 to 10 years on waiting list for ventilation tubes
Interventions	Otovent 3 times a day or no treatment for 3 months Control group received equal care except for the intervention
Outcomes	Tympanometry (1, 2 and 3 months) Pure‐tone audiometry (3 months) Clearance of fluid on otoscopy (1, 2 and 3 months) Adverse effects (3 months) Between 93.4% and 95.8% follow‐up; 45% had high compliance, 43% low and 12% were unable to use device
Notes	Results reported as ears Intervention group subdivided into low compliance and high compliance Original data obtained by JH and RP Groups were comparable at outset, except for smoke exposure
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random numbers
Allocation concealment (selection bias)	Unclear risk	Not stated
Comparability of groups at pre‐test	Unclear risk	"...significance only in the age distribution and exposure to smoking. Those in low compliance group were younger than those in the control group (p=0.04) and younger than those in the high compliance group (p=0.03). There was not difference between the high compliance and control groups."
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	Over 90% follow‐up at all outcome points for both intervention and control arms (by ears)
Selective reporting (reporting bias)	Low risk	No evidence of selective reporting