Villa 2015.

Study characteristics
Methods	Study design: parallel, RCT. Recruitment period: not reported. Duration of study: study start date: not reported. Actual study completion date: not reported. Study setting: outpatient. Pediatric Sleep Center (S. Andrea Hospital) Rome, Italy.
Participants	Key inclusion criteria: children 4 or more years old, with adenotonsillar hypertrophy and OSA (clinical cutoff value of AHI higher than 5 for moderate‐severe OSA) treated with adenotonsillectomy (AT), but in which residual OSA persist (residual OSA defined as an AHI index higher than 1 event/hour after AT and persistence of respiratory symptoms (snoring, oral breathing, and sleep apnoea). Key exclusion criteria: positive history for recurrent laryngospasm, allergy, asthma, acute or chronic cardiorespiratory or neuromuscular diseases, chronic inflammatory diseases, major craniofacial abnormalities, chromosomal syndromes, or epilepsy. Age (years): mean (SD): 6.01 (1.55) in intervention group and 5.76 (0.82) in control group. Gender: 24 boys, 3 girls. Comorbidities: not detailed. BMI: centile Mean (SD): 81.85 (29.94 ) in intervention group and 68.22 (28.68) in control group. AHI (events/hour): mean (SD): 4.82 (1.36). 4.87 (2.96) in intervention group and 4.56 (3.22) in control group. ESS: not assessed. PSQI: not assessed. N randomised: 30. N analysed: 27. Dropouts: 3, 2 from group 1 who did not comply with the exercises they were required to perform, and 1 from group 2 who not only did nasal washes but also nasal steroids for 3 months.
Interventions	Intervention: oropharyngeal exercises. "Oropharyngeal exercises were divided into three categories, i.e., nasal breathing rehabilitation, labial seal and lip tone exercises, and tongue posture exercises... Children were required to perform the exercises every day at home, at least three times a day, doing 10–20 repetitions each time. Children underwent three monthly meetings with a therapist. In the first meeting (T1), the therapist carried out a morphofunctional evaluation and taught the patients and their parents nasal breathing rehabilitation exercises and exercises designed to restore competence and lip tone, which children were required to perform daily at home for 2 months. All the patients were also required to fill in a diary in which their compliance to exercises was recorded. The aim of the second meeting was to ensure that the home exercises were being executed correctly. In the third meeting (T2), underwent the second morphofunctional evaluation." Duration of treatment 2 months. Comparator: control group (treated with nasal washing alone). Concomitant interventions: nasal washing was performed using the Neti Pot filled with 2.5 % saline hypertonic solution. All the participants performed nasal washing 2 times, in the morning and evening, for 2 months.
Outcomes	Prespecified outcomes: protocol not available. Reported outcomes: Apnea Hypopnea Index. ADHD‐RS. Morphofunctional evaluation form that assessed respiratory pattern (nasal or oral), labial seal (competent or not), and lip tone (normal or not). Glatzel and Rosenthal tests, which assess nasal patency. Time points of measurement: 2 months after the treatment.
Notes	Additional information on allocation procedures requested from authors, but no answer received. Funding for trial: none reported. Conflicts of interest: “The authors declare that they have no conflict of interest.” Sample size calculations: not reported. Registered: not reported. Data sharing statement: none.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Patients with residual OSA were randomised in two groups “. Comment: no description of the randomisation process.
Allocation concealment (selection bias)	Unclear risk	Not reported. Method of allocation concealment not mentioned.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Unblinded study.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Low risk for AHI or for morphofunctional evaluations “In order to reduce a possible observer bias, the therapist who performed all the morphofunctional evaluations in both groups at T1 and T2 was always the same and he was blinded to the group because another therapist had taught the exercises. Parents not blinded. High risk for parent‐assessed outcomes (ADHD‐RS).
Incomplete outcome data (attrition bias) All outcomes	Low risk	No serious imbalance in losses in compared intervention groups. Quotes: excluded “two from group 1 who did not comply with the exercises they were required to perform, and one from group 2 who not only did nasal washes but also nasal steroids for 3 months.” Per protocol analysis done.
Selective reporting (reporting bias)	Low risk	Protocol not available but they published outcome measurements relevant for the objectives of the study.
Other bias	Low risk	The study appears to be free of other sources of bias.

Abbreviations: AASM: American Academy of Sleep Medicine; ADHD‐RS: Attention Deficit Hyperactive Disorder Rating Scale; AHI: Apnea‐Hypopnea Index; AT: Adenotonsillectomy; BMI: Body Mass Index; CHF: Congestive Heart Failure; COPD: Chronic Obstructive Pulmonary Disease; CPAP: Continuous Positive Airway Pressure; ESS: Epworth Sleepness Scale; FOSQ: Functional Outcomes of Sleep Questionnaire; FSS: Fatigue Severity Scale; HST: Home Sleep Test; IMT: Inspiratory Muscle Training; MD: Mean Difference; MEP: Maximal Expiratory Pressure; MIP: Maximal Inspiratory Pressure; nCPAP: nasal Continuous Positive Airway Pressure; OSA: Obstructive Sleep Apnea; PSG: Polysomnography; PSQI: Pittsburgh Sleep Quality Index; RCT: Randomised Clinical Trial; SD: Standard Deviation; SMD: Standardised Mean Difference; SF‐36: 36‐item Short Form health survey; WHOQOL‐BREF: World Health Organization Quality of Life