Night-to-Night Variability of Novel Physiological Parameters in Home Sleep Apnea Testing (N2N-OSA)

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.

Study Overview

• Status: Not yet recruiting
• Conditions: Diagnostic; Sleep Apnea Syndrome (OSAS); Obstructive Apnea

• Study Type: Observational
• Enrollment (Estimated): 192

Contacts and Locations

Study Locations

• Switzerland
  • Bern, Switzerland, 3010
    • Inselspital University Hospital and University Bern
    • Contact: Samuel Tschopp, MD; Phone Number: 0041 31 632 29 41; Email: hno-poliklinik@insel.ch

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Participants with suspected or diagnosed sleep-disordered breathing of any severity will be recruited at Inselspital University Hospital und University Bern.

No selection or stratification based on sex, gender, or any other patient characteristics is applied during recruitment. Participants are included consecutively based on the clinical indication for home sleep apnea testing, irrespective of sex or gender. Any resulting imbalance reflects the underlying clinical population and does not compromise the scientific validity of the study, as analyses will account for sex and gender as covariates and report their effects transparently.

Description

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)

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
All participants; Participants will undergo repeated sleep testing using respiratory polygraphy over 4 nights and oximetry over 10 nights, starting in parallel. Before and after the recordings they will fill out symptom questionnaires and patient-reported outcome measures.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Night-to-night variability of apnea-hypopnea index (events per hour of sleep) over 4 nights	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.	4 nights of respiratory polygraphy
Night-to-night variability of oxygen desaturation index (events per hour of sleep) over 10 nights	The variability will be quantified using linear mixed-effects models, accounting for confounding variables.	4 nights of respiratory polygraphy and 10 nights of oxymetry
Night-to-night variability of hypoxic burden (minute x percent per hour of sleep) over 10 nights	The variability will be quantified using linear mixed-effects models, accounting for confounding variables.	4 nights of respiratory polygraphy and 10 nights of oxymetry
Night-to-night variability of ventilatory burden over 4 nights	The variability will be quantified using linear mixed-effects models, accounting for confounding variables. Ventilatory burden will be calculated according to Parekh et al.	4 nights of respiratory polygraphy
Night-to-night variability of heart rate variability over 10 nights	The variability will be quantified using linear mixed-effects models, accounting for confounding variables.	4 nights of respiratory polygraphy and 10 nights of oxymetry
Night-to-night variability of pulse wave amplitude drops (events per hour) over 10 nights	The variability will be quantified using linear mixed-effects models, accounting for confounding variables.	4 nights of respiratory polygraphy and 10 nights of oxymetry

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Identification of factors contributing to and explaining variability	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	4 nights of respiratory polygraphy and 10 nights of oxymetry
Correlation between physiological parameters from sleep testing and patient-reported outcome measures (PROMs)	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)	4 nights of respiratory polygraphy and 10 nights of oxymetry

Collaborators and Investigators

• Sponsor: Insel Gruppe AG, University Hospital Bern

Study record dates

Study Major Dates

• Study Start (Estimated): May 1, 2026
• Primary Completion (Estimated): June 30, 2027
• Study Completion (Estimated): June 30, 2027

Study Registration Dates

• First Submitted: April 16, 2026
• First Submitted That Met QC Criteria: April 23, 2026
• First Posted (Actual): April 29, 2026

Study Record Updates

• Last Update Posted (Actual): May 5, 2026
• Last Update Submitted That Met QC Criteria: April 28, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Home Sleep Apnea Testing
• Additional Relevant MeSH Terms: Nervous System Diseases; Pathologic Processes; Respiratory Tract Diseases; Respiration Disorders; Sleep Wake Disorders; Apnea; Sleep Disorders, Intrinsic; Dyssomnias; Pathological Conditions, Signs and Symptoms; Disease; Sleep Apnea Syndromes; Sleep Apnea, Obstructive
• Other Study ID Numbers: 2026-00237

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No