Timeline of data collection

Data collectedBaseline#Follow-up
Demographics (age, sex, BMI, postal code)X
Sleep study (RDI, REI, AHI, nocturnal SpO2)X
CPAP adherence (machine download)X
Wait times and cost of OSA care+XX

BMI: body mass index; RDI: respiratory disturbance index; REI: respiratory event index; AHI: apnoea–hypopnoea index; nocturnal SpO2: mean and lowest nocturnal oxygen saturation; CPAP: continuous positive airway pressure; ESS: Epworth Sleepiness Scale; VSQ-9: Visit-Specific Satisfaction Instrument; EQ-5D-3L: EuroQOL-5D-3 level; OSA: obstructive sleep apnoea. #: Baseline data will be collected from consenting patients at the time of CPAP initiation; : follow-up data will be collected after 3 months of treatment with CPAP; +: baseline and follow-up “Wait Times and Cost of OSA Care” questionnaires include different questions. See supplementary appendix 3.