Fractional Exhaled Nitric Oxide as Possible Non - Invasive Biomarker to Assess Obstructive Sleep Apnea Severity

May 25, 2026 updated by: Martina Reda Abdo, Tanta University

Aim of work

  1. Primary aim: Asses correlation between FeNO level, OSA severity
  2. Secondary aim: Clarifying FeNO's role as a biomarker to assess airway inflammation, Cut off value prediction to moderate and severe OSA and its potential significance to improve clinical management strategies for OSA patients.

Study Overview

Status

Active, not recruiting

Conditions

Detailed Description

Obstructive Sleep Apnea is a highly prevalent sleep-related breathing disorder characterized by recurrent episodes of upper airway obstruction during sleep, resulting in intermittent hypoxia, sleep fragmentation, and significant cardiometabolic consequences. The severity of OSA is traditionally assessed using overnight polysomnography (PSG), with the apnea-hypopnea index (AHI) serving as the gold standard metric. However, PSG is resource-intensive, time-consuming, and not readily accessible in many healthcare settings, particularly in resource-limited environments. This has driven increasing interest in identifying reliable, non-invasive biomarkers that could aid in the assessment of disease severity and reduce dependence on PSG.(1) Airway and systemic inflammation play a central role in the pathophysiology of OSA. Recurrent hypoxia-reoxygenation cycles induce oxidative stress and activate inflammatory pathways, leading to endothelial dysfunction and tissue injury.(1) Fractional exhaled nitric oxide (FeNO) is a well-established non-invasive biomarker of airway inflammation, widely used in the assessment of eosinophilic airway diseases such as asthma. Given its ability to reflect inflammatory processes within the respiratory tract, FeNO has been proposed as a potential marker in OSA.(2) Several studies have explored the relationship between FeNO levels and OSA. Some have demonstrated elevated FeNO levels in patients with OSA compared to healthy controls, along with positive correlations between FeNO and indices of disease severity such as AHI and oxygen desaturation index (ODI).(3) In contrast, other studies have reported inconsistent or weak associations, suggesting that the inflammatory profile in OSA (often predominantly neutrophilic rather than eosinophilic) may limit the specificity of FeNO as a biomarker in this context.

Importantly, the current literature is characterized by several limitations. Many studies have small sample sizes, heterogeneous populations, and inadequate control for confounding factors such as smoking, obesity, and coexisting airway diseases. Furthermore, most studies focus primarily on simple correlations with AHI, without evaluating the diagnostic performance of FeNO or its ability to discriminate between different severity categories of OSA. The absence of robust predictive models integrating FeNO with clinical parameters further limits its applicability in routine clinical practice.(4) Therefore, a significant gap remains regarding whether FeNO can serve as a clinically meaningful, non-invasive biomarker for stratifying OSA severity. In particular, there is a need for well-designed studies that not only assess the association between FeNO and polysomnographic parameters, but also evaluate its diagnostic accuracy and potential role within predictive models.

Accordingly, the present study aims to investigate the role of FeNO in assessing the severity of OSA, to determine its relationship with key polysomnographic indices, and to evaluate its potential utility as a non-invasive tool for disease stratification.

Study Type

Observational

Enrollment (Estimated)

200

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Egypt
      • Tanta, Egypt
        • Tanta university

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Study Type: prospective observational cross sectional study. Sample Size: This study will be carried out on 200 patients' suspected for obstructive sleep apnea, following approval of medical research ethical committee of Tanta University, Faculty of Medicine.

Sample size was calculated using this formula 2SD ^2 × (1.96 + 0.84)^2 /d^2 SD of FeNO 50 at moderate OSA 17.25 d is the difference between both means 21, 13.57 So at power of study 80% CI 95% Least Sample size will be 85 in each group

Description

Inclusion Criteria:

  • Ages Eligible for study: 18 years till 70 years old.
  • Newly suspected OSA patients with Epworth Sleepiness Scale (ESS) ≥ 10.

Exclusion Criteria:

  • Current smokers.
  • Any chronic Respiratory disorders other than OSA (asthma, COPD, allergic rhinitis, and atopic diseases).
  • Younger age than 18 years.
  • Recent inhaled or systemic corticosteroids within the pasr 4 weeks.
  • Recent respiratory infection less than 4 weeks.
  • Uncontrolled diabetes & any chronic debilitating diseases (liver, renal, collagen diseases) Informed Consent will be taken from the participants before clinical examination.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
• Control group AHI less than 5 \ hour - case groups Milld OSA & moderate to severe OSA

All 200 participants will undergo:

  • History taking including: Age, sex, occupation, residence, education, and special habits e.g., smoking
  • Plain chest x ray& PFT to exclude any other chest diseases (asthma& COPD)
  • The participants' Blood pressure, height and weight will be measured, and body mass index will be calculated.
  • Daytime sleepiness will be assessed by the Epworth Sleepiness Scale and a value of 10 or more denoting as excessive daytime sleepiness.
  • Full laboratory investigation to exclude any chronic diseases.
  • Full-night PSG in chest department, Tanta university hospital.
  • FENO level base line at 9 am after PSG night & interpretation accordin

  • After PSG result, cases will be divided in 3 groups

    • Control group AHI less than 5 \ hour
    • Mild OSA group AHI than 5-15 \ hour
    • Mod to severe OSA more than 15 \ hour

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Asses correlation between FeNO level, OSA severity• through measuring FeNo level in 3 groups which will be divided according to AHI in PSG study -Control group AHI less than 5 \ hour, Mild OSA group AHI than 5-15 \ hour, Moderate to severe OSA group
Time Frame: baseline

address the correlation between PSG parameters performed by Somno medics screen including (apnea hypopnea index (event\ hour) oxygen nadir(%), oxygen desaturation index, % of time desaturation below 90% (T90), snoring index) and FeNo level ppb which measured by (Bedfont NIN006187 Nobreath) to Clarify FeNO's role as a biomarker to assess airway inflammation, and OSA severity, address FeNoCut off value as prediction tool to moderate and severe OSA and its potential significance to improve clinical management strategies for OSA patients.

FeNo measurement precaution will be addressed as the participants will be asked to abstain from eating, drinking, and exercise, and avoid exposure to tobacco fumes 60 minutes before testing, so all cases FeNO assay will be hold at 9 am, Ask patients to refrain from Intake of nitrate-containing food like green-leaved vegetables on the day of assessment and then will be interprated according to ATS guidelines
baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Tanta University

Investigators

  • Study Director: Mohammed Sayed Hantira, professor, Tanta university
  • Study Chair: Ayman Hassan AbdElzaher, professor, Tanta university
  • Study Chair: Ahmed Gharib Gharib, assistant professor, cairo institute for research
  • Principal Investigator: Mohammed Samy Torky, assistant professor, Tanta university

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

May 25, 2026

Primary Completion (Estimated)

September 1, 2026

Study Completion (Estimated)

October 1, 2026

Study Registration Dates

First Submitted

May 12, 2026

First Submitted That Met QC Criteria

May 18, 2026

First Posted (Actual)

May 26, 2026

Study Record Updates

Last Update Posted (Actual)

May 28, 2026

Last Update Submitted That Met QC Criteria

May 25, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • FeNo in OSA

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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