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Enrolling by Invitation

NCT Number: NCT02624362

The Effect of Odors on Asthma Symptoms

An extended replication of Jaen & Dalton (2014), the investigators aim to investigate the role of odors and associated trigger beliefs on symptom perception and airway inflammation in individuals with asthma

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Key information

Conditions

Asthma Bronchial Diseases Hypersensitivity Hypersensitivity, Immediate Immune System Diseases Inflammation Lung Diseases Lung Diseases, Obstructive Pathologic Processes Pathological Conditions, Signs and Symptoms Respiratory Hypersensitivity Respiratory Tract Diseases

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

UZ Leuven

Leuven, 3000, Belgium

About this study

Participants with asthma are randomly assigned to a 15-min (phenylethyl alcohol) odor inhalation, accompanied by either an asthmogenic suggestion (nocebo), or a therapeutic suggestion (placebo). Airway inflammation, lung function, and asthma symptoms are measured in response to the odor/suggestion, up to 24 hours after odor inhalation. The investigators are also measuring worry and heart rate variability as potential mediators of the response.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • A physician diagnosis of asthma

Exclusion criteria

  • FEV1 lower than 60% predicted
  • clinical condition other than asthma

Treatment and study plan

Therapeutic Suggestion

Behavioral

suggestions about potential beneficial effects of the odor are given

Other names: placebo suggestion, positive treatment belief induction

Asthmogenic Suggestion

Behavioral

suggestions about potential negative effects of the odor are given

Other names: nocebo suggestion, negative treatment belief

Phenylethyl Alcohol odor

Other

Over the course of 15 minutes, participants, receive 15 short sniffs of Phenylethyl Alcohol odor

Primary outcomes

  1. Change from Baseline Exhaled Nitric Oxide to 24 hours after odor induction

    Time frame: baseline, immediately after odor induction, 2 hours after odor induction, 24 hours after odor induction

    Fraction of exhaled nitric oxide

Secondary outcomes

  1. asthma symptoms

    Time frame: baseline, immediately after odor induction, 2 hours after odor induction, 24 hours after odor induction

    measured using the Asthma Symptom Checklist

  2. Forced Expiratory Volume at one second (FEV1)

    Time frame: baseline, immediately after odor induction, 2 hours after odor induction, 24 hours after odor induction

    Measured using Jaeger Masterscreen Spirometer, according to ERS-ATS guidelines

  3. Worry

    Time frame: baseline, immediately after odor induction, 2 hours after odor induction, 24 hours after odor induction

    measured using worry Visual Analog Scales

  4. Cortisol

    Time frame: baseline, immediately after odor induction, 2 hours after odor induction, at awakening, 30 min after awakening, 24 hours after odor induction

    cortisol awakening response (AUC), and changes in cortisol (AUC) will be measured using saliva sampling

  5. Change in Heart rate and Heart Rate Variability (HRV)

    Time frame: change from baseline to 24 hours after odor induction

    24 hour heart rate data will be recorded using an ambulatory ECG monitor, and analyzed in 1 hour epochs, extracting mean of successive differences (MSD) as a variable of interest.

  6. Change in Respiratory rate

    Time frame: change from baseline to 15 min odor presentation

    respiratory rate (breaths/min) is recorded continuously, and changes between baseline and odor presentation periods will be analysed

  7. change in Fraction of end-tidal carbon dioxide (FetCO2)

    Time frame: change from baseline to 15 min odor presentation

    FetCO2 (plateau %CO2 in exhaled air) is recorded continuously, and changes between baseline and odor presentation periods will be analysed

Sponsors and collaborators

Lead sponsor

Universitaire Ziekenhuizen KU Leuven

Other

Collaborators

  • KU Leuven
  • Research Foundation Flanders

Registry information

Official study title

The Effect of Suggestion of Harmful/Beneficial Effects of Odors on Asthma Symptoms

Important dates

Study start
2015
Primary completion
2026
Study completion
2026
First posted
Dec 8, 2015
Registry last updated
Jul 3, 2024

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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