Dai 2014.

Study characteristics
Methods	Non‐blinded, parallel‐group randomised controlled surgical trial with 3‐month duration of follow‐up
Participants	Setting: general hospital, China Sample size: Number randomised: 57 children Number completed: 57 children Participant (baseline) characteristics: Age: 2 to 12 years Gender: 67% males, 33% females Inclusion criteria: positive polysomnography for OSAHS (AHI > 5/hour and/or AI >1/hour, lowest oxygen saturation < 92%), adenoid hypertrophy (A/N ratio ≥ 0.71 on nasopharyngeal lateral radiographs), tonsil hypertrophy on physical exam (bilateral tonsils beyond velopharyngeal bow – Grade III), absence of CRS (paranasal sinus computed tomography) Exclusion criteria: chronic sinusitis, allergic rhinitis, recurrent acute tonsillitis, chronic respiratory disease, nephritis, systemic allergic disease and URTI in 2 weeks prior to surgery
Interventions	Intervention group: tonsillectomy (TE) by low‐temperature plasma radiofrequency ablation (n = 20) Comparator group: tonsillotomy (TT) by low‐temperature plasma radiofrequency ablation (n = 37) Use of additional interventions: not stated
Outcomes	Short‐term outcomes (1 and 3 months): humoral immunity (serum levels of immunoglobulins A, G and M), cellular immunity (serum levels of T cells CD3+/CD4+/CD8+)
Notes	Participants analysed: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "randomly divided" – no method given
Allocation concealment (selection bias)	Unclear risk	Method not described
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not blinded
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not blinded
Incomplete outcome data (attrition bias) All outcomes	High risk	Not clear if there was any loss of data due to no statement of data numbers analysed
Selective reporting (reporting bias)	Unclear risk	No protocol available; insufficient information to permit a judgement of low or high risk
Other bias	High risk	Baseline characteristics: not balanced for gender (M 67%:F 33%) or group size (35% TE:64% TT) ITT analysis: performed Formal sample size calculations: not performed Use of co‐interventions: not stated across groups