Timeline of data collection
| Data collected | Baseline# | Follow-up¶ |
| Demographics (age, sex, BMI, postal code) | X | |
| Sleep study (RDI, REI, AHI, nocturnal SpO2) | X | |
| CPAP adherence (machine download) | X | |
| ESS | X | X |
| VSQ-9 | X | |
| EQ-5D-3L | X | X |
| Wait times and cost of OSA care+ | X | X |
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.