Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Hearing
Systematic review 3-armed trial	79 ears Data from 1 RCT	Hearing 6 months with adenoidectomy with no treatment Absolute results not reported	Mean difference 16.1 dB Reported as significant 95% CI presented graphically	Effect size not calculated	Adenoidectomy
Systematic review 3-armed trial	79 ears Data from 1 RCT	Hearing 12 months with adenoidectomy with no treatment Absolute results not reported	Mean difference 7.7 dB Reported as significant 95% CI presented graphically	Effect size not calculated	Adenoidectomy
Systematic review 4-armed trial	74 ears Data from 1 RCT	Hearing 6 months with adenoidectomy with no treatment Absolute results not reported	Mean difference 4.3 dB Reported as not significant 95% CI presented graphically		Not significant
Systematic review 4-armed trial	74 ears Data from 1 RCT	Hearing 12 months with adenoidectomy with no treatment Absolute results not reported	Mean difference 4.3 dB Reported as not significant 95% CI presented graphically		Not significant
Systematic review 4-armed trial	72 ears Data from 1 RCT	Hearing 6 months with adenoidectomy with no treatment Absolute results not reported	Mean difference 3.1 dB Reported as not significant 95% CI presented graphically		Not significant
Systematic review	72 ears Data from 1 RCT	Hearing 12 months with adenoidectomy with no treatment Absolute results not reported	Mean difference 2.8 dB Reported as not significant 95% CI presented graphically		Not significant
Duration of otitis media with effusion (OME)
RCT	79 ears	Median duration of otitis media with effusion 5 years 4.0 years with adenoidectomy 7.8 years with no treatment	P = 0.001	Effect size not calculated	Adenoidectomy