Appelman 1991.

Methods	Randomised ‐ yes, computer‐generated random numbers Concealment of allocation ‐ adequate Double‐blind ‐ yes, blinding procedure not described Intention‐to‐treat (ITT) ‐ unclear Loss to follow‐up ‐ described Design ‐ parallel
Participants	N ‐ 126 children (N = 121 children included in analysis) Age ‐ between 6 months and 12 years Setting ‐ general practice and secondary care in the Netherlands; confirmation of diagnosis and randomisation were done by otorhinolaryngologists Inclusion criteria ‐ recurrence of acute otitis media (AOM) characterised by a (sub)acute onset, otalgia and otoscopic signs of middle‐ear infection within 4 weeks to 12 months of the previous attack Exclusion criteria ‐ antibiotic treatment < 4 weeks prior to randomisation, previous participation in this study, contraindication for penicillin, serious concurrent disease that necessitated antibiotic treatment Baseline characteristics ‐ balanced
Interventions	Tx ‐ amoxicillin/clavulanate (weight tailored dose) for 7 days; N = 70 (N = 67 included in analysis) C ‐ matching placebo for 7 days; N = 56 (N = 54 included in analysis) Use of additional medication ‐ each child was given analgesics (paracetamol) as long as earache was present and decongestive nose drops for 1 week
Outcomes	Primary outcome ‐ treatment failure (i.e. presence of otalgia or fever > 38 °C or both at 3 days) Assessment by (blinded) general practitioner at 3 days on the presence or absence of fever (> 38 °C) and otalgia and 14 days on the presence or otorrhoea Assessment by otorhinolaryngologist at 1 month of otoscopy, tympanometry and in children > 3 years of age an audiogram
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random numbers
Allocation concealment (selection bias)	Low risk	Treatment allocated by otolaryngologist (independent to trial personnel); treatment code placed in sealed envelopes
Other bias	Unclear risk	ITT analysis ‐ unclear, baseline characteristics ‐ balanced
Blinding of participants and personnel (performance bias)	Unclear risk	Identical taste and appearance to amoxicillin/clavulanate and placebo not described
Incomplete outcome data (attrition bias)	Low risk	Loss to follow‐up ‐ treatment: N = 3 (4%) and placebo: N = 2 (4%) due to loss of their registration forms