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NCT Number: NCT07555119

Night-to-Night Variability of Novel Physiological Parameters in Home Sleep Apnea Testing

Obstructive sleep apnea (OSA) is usually diagnosed from a single night of home sleep apnea testing using the apnea-hypopnea index (AHI). However, the AHI varies substantially from night to night, undermining diagnostic accuracy, and shows only modest correlation with symptoms. This variability further limits its usefulness for predicting cardiovascular and other complications. Besides the traditional AHI, more robust physiological markers are needed.

Several emerging physiological metrics - hypoxic burden, ventilatory burden, heart rate variability, autonomic arousals, and the pulse wave amplitude drop index - capture the physiological impact of OSA more comprehensively and demonstrate stronger associations with cardiovascular risk. Despite this promise, their night-to-night variability has not been studied.

A systematic evaluation of both established and novel OSA metrics across nights is essential to identify reliable, stable parameters suitable for clinical routine. This improves diagnostic precision beyond what traditional metrics can provide, enhances patient selection, reduces costs and patient harm, and may improve treatment outcomes.

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Key information

Conditions

Obstructive Apnea Apnea Diagnostic Disease Dyssomnias Nervous System Diseases Pathologic Processes Pathological Conditions, Signs and Symptoms Respiration Disorders Respiratory Tract Diseases Sleep Apnea Syndrome (OSAS) Sleep Apnea Syndromes Sleep Apnea, Obstructive Sleep Disorders, Intrinsic Sleep Wake Disorders

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patients with suspected or diagnosed sleep-disordered breathing, irrespective of disease severity, as defined by the indications for home sleep apnea testing in the German guidelines [15]
  • No active treatment during sleep recordings or within preceding two weeks (e.g., mandibular advancement devices, positive airway pressure therapy)
  • Written informed consent obtained

Exclusion criteria

  • Age <18 years
  • Known or suspected neurological sleep disorder (e.g., narcolepsy, parasomnia)
  • Known or suspected psychiatric sleep disorder
  • Known or suspected central and complex sleep apnea
  • Participants who are unable to perform sleep measurements reliably
  • Insufficient knowledge of the project language (German)
  • Inability to give consent
  • Shift workers (with shift work <2 weeks before testing)

Treatment and study plan

Primary outcomes

  1. Night-to-night variability of apnea-hypopnea index (events per hour of sleep) over 4 nights

    Time frame: 4 nights of respiratory polygraphy

    The variability of the apnea-hypopnea index (events per hour of sleep) over 4 nights will be quantified using linear mixed-effects models, accounting for confounding variables.

  2. Night-to-night variability of oxygen desaturation index (events per hour of sleep) over 10 nights

    Time frame: 4 nights of respiratory polygraphy and 10 nights of oxymetry

    The variability will be quantified using linear mixed-effects models, accounting for confounding variables.

  3. Night-to-night variability of hypoxic burden (minute x percent per hour of sleep) over 10 nights

    Time frame: 4 nights of respiratory polygraphy and 10 nights of oxymetry

    The variability will be quantified using linear mixed-effects models, accounting for confounding variables.

  4. Night-to-night variability of ventilatory burden over 4 nights

    Time frame: 4 nights of respiratory polygraphy

    The variability will be quantified using linear mixed-effects models, accounting for confounding variables. Ventilatory burden will be calculated according to Parekh et al.

  5. Night-to-night variability of heart rate variability over 10 nights

    Time frame: 4 nights of respiratory polygraphy and 10 nights of oxymetry

    The variability will be quantified using linear mixed-effects models, accounting for confounding variables.

  6. Night-to-night variability of pulse wave amplitude drops (events per hour) over 10 nights

    Time frame: 4 nights of respiratory polygraphy and 10 nights of oxymetry

    The variability will be quantified using linear mixed-effects models, accounting for confounding variables.

Secondary outcomes

  1. Identification of factors contributing to and explaining variability

    Time frame: 4 nights of respiratory polygraphy and 10 nights of oxymetry

    Each influencing factor will be evaluated on its potential to explain the observed variability in the objective physiological parameters listed above. Each factor will be included individually as a fixed effect in the mixed-effects model and tested for significance.

    The following factors will be analyzed:

    • Age (years)
    • Body mass index (kg(m2)
    • Gender
    • Upper airway anatomy (tonsil size)
    • Mean OSA severity over all nights (of the respective parameter)
    • Sleep position (supine time as a percent of sleep time)
    • Alcohol consumption (number of drinks)
    • Caffeine intake (number of cups)
    • Nicotine use (number of packages)
    • Sleep Medication (free text)
    • Subjective sleep quality (visual analog scale, VAS, 0 to 10 points)
    • Snoring intensity (VAS, 0 to 10 points)
    • Daytime sleepiness on a VAS of the subsequent day (0 to 10 points)
    • Daytime sleepiness on the Epworth Sleepiness Scale of the subsequent day (0 to 24 points)
    • Respiratory symptoms such as infection (VAS)
    • Allergy symptoms

  2. Correlation between physiological parameters from sleep testing and patient-reported outcome measures (PROMs)

    Time frame: 4 nights of respiratory polygraphy and 10 nights of oxymetry

    Associations between physiological metrics and PROMs will be assessed using mixed-effects models, analogously to the analysis of influencing factors above and correlation analysis (Spearman's rank coefficient).

    Patient-reported symptoms for correlation analyses:

    • Sleep quality on a VAS (0 to 10 points)
    • Snoring intensity on a VAS (0 to 10 points)
    • Daytime sleepiness on a VAS (0 to 10 points)
    • Epworth Sleepiness Scale (0 to 24 points)

Sponsors and collaborators

Lead sponsor

Insel Gruppe AG, University Hospital Bern

Other

Registry information

Acronym: N2N-OSA

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Apr 29, 2026
Registry last updated
May 5, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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