Tao 2020.

Study characteristics
Methods	2‐arm, randomised, parallel‐group, open, controlled trial with 12 months of follow‐up Randomised by child
Participants	Location: China, single centre Setting of recruitment and treatment: ENT Department, Guangzhou Women and Children's Medical Center Study dates: January 2016 to June 2018 Sample size: Number randomised: 178 (90 in VT plus adenoidectomy group, 88 in myringotomy plus adenoidectomy group) Number completed: 169 (87 in VT plus adenoidectomy group, 82 in myringotomy plus adenoidectomy group) Participant (baseline) characteristics: Age (years): VT plus adenoidectomy mean 7.0 (SD 1.9) years; LM plus adenoidectomy mean 7.2 (SD 2.4) years Gender: VT males 42/87 (48%), females 45/87 (52%); LM males 42/82 (51%), females 40/82 (49%) Inclusion criteria: Bilateral otitis media with effusion diagnosed by air‐drum otoscopy and confirmed by acoustic impedance examination (Type B) Electronic nasopharyngoscopy‐confirmed adenoid hypertrophy blocking more than 1/2 of the posterior nares Middle ear effusion persisting longer than 3 months after conservative treatment, which includes nasal corticosteroids, oral montelukast sodium, oral mucoactive agents and modified Eustachian tube insufflation, plus added antibiotics if complicated by acute sinusitis Average bilateral hearing threshold exceeding 25 dB HL for 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz Patients aged 4 to 12 years Exclusion criteria: A previous history of nose, ear or nasopharyngeal surgery Cleft palate or other congenital malformations that may affect the state of the middle ear Congenital or acquired immune deficiency Sensorineural hearing loss or mixed hearing loss
Interventions	Ventilation tube: Myringotomy was performed to suck out the intratympanic fluid, and then a conical short‐acting silicon middle ear ventilation tube was placed Myringotomy: Myringotomy was performed under otoendoscope; the intratympanic fluid was sucked out Interventions administered to both groups: Low temperature plasma radiofrequency ablation of the adenoids was performed, which was assisted by indirect nasopharyngoscopy with entry through the mouth, taking care to avoid damage to the Torus tubarius and the pharyngeal opening of the Eustachian tube
Outcomes	Persistent perforation Persistence of OME ‐ these data were not used in the review, as data were only reported for one group at 3 months follow‐up, and data from later time points will be affected by the use of different additional treatments in each arm. Adverse events
Funding sources	Not reported
Declarations of interest	—
Notes	Research integrity checklist: No retraction notices or expressions of concern were noted No prospective trial registration was identified Baseline characteristics were not excessively similar between the two groups Plausible loss to follow‐up was reported No implausible results were found Different numbers of participants were allocated to each group
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	“All patients were randomly divided into two groups, namely Group A and B, according to the sequence generated by a computer program when they were admitted to the hospital.”
Allocation concealment (selection bias)	Unclear risk	Insufficient information to assess.
Blinding of participants and personnel (performance bias) All outcomes	High risk	There was no report of blinding. Blinding of patients and personnel may not have been feasible for operative interventions. However, lack of blinding could influence outcomes.
Blinding of outcome assessment (detection bias) All outcomes	High risk	There was no report of blinding. Blinding of patients and personnel may not have been feasible for operative interventions. However, lack of blinding could influence outcome interpretation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Low attrition rate.
Selective reporting (reporting bias)	Unclear risk	No protocol was available to assess.
Other bias	Unclear risk	Insufficient detail in the report to assess whether an important risk of bias exists.