Goswami 2019.

Study characteristics
Methods	Study design: parallel, RCT. Recruitment period: not available. Duration of study: study start date: 15 December 2016. Actual study completion date: 18 May 2017. Study setting: outpatient. University of Minnesota Medical Center sleep clinic.
Participants	Key inclusion criteria: between 20 and 65 years of age, fluent in English, and with a BMI equal or lower than 32 kg/m2; participants had to be habitual snorers (self‐reported or bed partner reported snoring three or more nights a week) with a PSG or HST within the past year that showed objective snoring with no more than mild obstructive sleep apnoea (AHI 0– 14). For both PSG and HST, apneas were defined as a drop equal or higher than 90% in peak signal excursion of the apnoea sensor for 10 seconds or more while hypopnoeas were defined as a drop equal or higher than 30% from peak signal excursion of the airflow sensor associated with oxygen desaturation equal or higher than 4% from pre‐event baseline. AHI was calculated in accordance with the AASM rules, terminology, and technical specifications. Key exclusion criteria: anyone with comorbid sleep disorders (significant insomnia, uncontrolled restless legs syndrome, chronic insufficient sleep intake, or pathological excessive daytime sleepiness, i.e., ESS higher than 11), significant medical comorbidities including decompensated cardiopulmonary disease and chronic rhinitis, self‐reported average of three or more alcoholic drinks per day, or significant daily opioid use. Those currently using CPAP were excluded. To minimize variation in OSA risk factors, authors excluded anyone with higher than 5% weight change since their sleep apnoea evaluation. Given data collection procedures, they excluded participants with a less than 10 megabytes per second WiFi connection where they sleep, inability to sleep in a quiet environment, or a loud snorer as a bed partner. Age (years): mean (SD): 51 (11) in intervention group and 51 (10) in control group. Gender: 6 women, 10 men. Comorbidities: not detailed. BMI: mean (SD): 27.5 (3.4) in intervention group and 27.4 (3.8) in control group. AHI (events/hour): mean (SD): 9.2 (4.0) in intervention group and 8.2 (3.2.) in control group. ESS: mean (SD): 8 (3.5.) in intervention group and 7 (4.0) in control group. PSQI: not measured. N randomised: 32. N analysed: 16, 8 in each comparison group. Dropouts: 16, 8 in each comparison group.
Interventions	Intervention: oropharyngeal exercises. Smartphone application that requires users to articulate phonemes to achieve voice‐controlled onscreen objectives. The exercise routine comprises three different games of 5 minutes each, played consecutively for a total of 15 minutes daily. These games focus on improving endurance, strength, and coordination of upper airway muscles by moving the user’s tongue base forwards and backwards repeatedly. Game 1 prompts the user to repeatedly enunciate the /i/ sound to perform the on‐screen objective, with the aim of building endurance by holding the tongue forward. Game 2 is designed to improve strength by inducing pulsing of the tongue in forward and backward motion through vocalization of /i/ and /a/ to control the on‐screen object. Game 3 prompts articulation of /i/, /u/, and /a/ to improve coordination by navigating the tongue through different zones. Duration of treatment, up to 12 weeks. Comparator: a daily 'check‐in' on a mobile application but without exercises. Concomitant interventions: participants using mandibular advancement device and nasal dilator strips routinely were restricted from using these on the nights of sleep recording for the study duration.
Outcomes	Prespecified outcomes: Primary Outcome Measures: Snoring intensity (snoring sounds higher than 60 dBA per hour of sleep). Snoring rate (snoring sounds/hour of sleep). Secondary Outcome Measures: Sleep quality: self‐reported on Likert scale (0 to 5). Bed partner sleep quality: reported on Likert scale (0 to 5). Daytime sleepiness (ESS) Time points of measurement: before and 12 weeks after the treatment. Reported outcomes: they did not report results on sleep quality, nor on sleepiness.
Notes	Additional information requested and received from authors on allocation procedures. Funding for trial: NIH Research Evaluation and Commercialization Hub (MN‐REACH) Grant no. 5U01HL127479‐03. Conflicts of interest: quote: “Umesh Goswami: holds equity in the entity aimed at commercialisation of the technology described in this manuscript; Adam Black: holds the provisional patent of the technology described in this manuscript and holds equity in the entity aimed at commercialisation of the technology; Brian Krohn: holds the provisional patent of the technology described in this manuscript and holds equity in the entity aimed at commercialisation of the technology.” Registered: ClinicalTrials.gov: NCT03264963. Sample size calculations: not reported. Data sharing statement: none.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "we randomly assigned participants”. Additional information from authors: “1:1 randomisation using computer generated random numbers.”
Allocation concealment (selection bias)	High risk	Not done.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quotes: “The participants were not blinded to their assignment of the study arm.” “Masking: None (Open Label)”.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Participants not blinded. High risk for participant‐assessed outcomes such as daytime sleepiness or sleep quality. Low risk for snoring measurements. Quote: “A non‐contact microphone … was positioned 30 cm above the participant’s mouth during sleep to optimise signal quality and patient comfort … to record sound levels. Data were collected and stored in de‐identified form, assigned to a unique participant ID.”
Incomplete outcome data (attrition bias) All outcomes	Low risk	Equal percentages of losses in both compared groups. Quotes: “Despite instructions to record their sleep environment sounds twice weekly, participants’ recording frequency varied. Over the study period, 16 participants (8 intervention group, 8 control group) met the requirement of recording 12 nights of sleep for 5 h or longer. Data from these 16 participants were analysed”. "In the control group 2 participants withdrew after randomisation before activity and 6 did not complete the minimum of 12 nighttime recordings of at least 5 hours in length.” “Participants were considered to have completed the protocol if they produced at least 12 recordings of ≥ 5 h each (primary end point).”
Selective reporting (reporting bias)	Low risk	Pre‐specified relevant outcomes in clinicaltrials.gov were reported.
Other bias	Low risk	The study appears to be free of other sources of bias.