Sleep Apnea Biomarkers and Adherence to Continuous Positive Airway Pressure

Association between hypoxic burden measured during the baseline diagnostic sleep study and mean nightly CPAP use during the 30 days preceding the 3-month visit. CPAP adherence will also be categorized as less than 4 hours per night versus 4 hours or more per night.

Distribution of hypoxic burden, pulse wave amplitude drop index, and heart rate response measured or calculated from the baseline respiratory polygraphy or polysomnography. Results will be described according to sex, age, body mass index, medical history, cardiovascular history, and current treatments.

Association between the heart rate response to respiratory events (delta heart rate) measured during the baseline diagnostic sleep study and mean nightly CPAP use during the 30 days preceding the 3-month visit. CPAP adherence will also be categorized as less than 4 hours per night versus 4 hours or more per night.

Association between the pulse wave amplitude drop index (PWAD index) measured during the baseline diagnostic sleep study and mean nightly CPAP use during the 30 days preceding the 3-month visit. CPAP adherence will also be categorized as less than 4 hours per night versus 4 hours or more per night.

Daytime sleepiness will be assessed using the Epworth Sleepiness Scale at baseline and 3 months after CPAP initiation. The total score ranges from 0 to 24, with higher scores indicating greater daytime sleepiness and therefore a worse outcome. The change in total score between baseline and 3 months will be evaluated.

Health-related quality of life will be assessed using the EuroQol 5-Dimension 5-Level questionnaire (EQ-5D-5L) at baseline and 3 months after CPAP initiation. The EQ-5D-5L evaluates five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension has five response levels, ranging from 1 (no problems) to 5 (extreme problems or inability to perform the activity). Responses will be converted into an EQ-5D-5L utility index using the French value set. Index values range from -0.525 to 1, with higher values indicating better health-related quality of life. The change in the utility index between baseline and 3 months will be evaluated.

Goal Attainment Scaling score and its change between baseline and the 3-month follow-up visit. Attainment of the participant's individualized treatment goal will be assessed at 3 months using Goal Attainment Scaling (GAS). Goal attainment is rated on a five-point scale ranging from -2 to +2: -2 indicates a much worse outcome than expected, -1 a somewhat worse outcome than expected, 0 the expected level of goal attainment, +1 a somewhat better outcome than expected, and +2 a much better outcome than expected. Higher scores indicate better goal attainment and therefore a better outcome

Sleep apnea-specific hypoxic burden will be calculated from the oxygen desaturation area associated with respiratory events and expressed as percent-minutes per hour (%min/h). The change from the baseline diagnostic sleep study to the sleep study performed during CPAP therapy at 3 months will be evaluated. Higher values indicate a greater hypoxic burden and therefore a worse outcome. This assessment will be performed only in participants undergoing a follow-up sleep study as part of routine care.

The pulse wave amplitude drop index will be calculated as the number of pulse wave amplitude drops per hour of sleep or recording. The change from the baseline diagnostic sleep study to the sleep study performed during CPAP therapy at 3 months will be evaluated. Higher values indicate more frequent pulse wave amplitude drops. This assessment will be performed only in participants undergoing a follow-up sleep study as part of routine care.

Heart rate response will be measured as the mean change in heart rate associated with respiratory events (delta heart rate). The change from the baseline diagnostic sleep study to the sleep study performed during CPAP therapy at 3 months will be evaluated. Higher values indicate a greater heart rate response to respiratory events. This assessment will be performed only in participants undergoing a follow-up sleep study as part of routine care.