The Effect of Suggestion of Harmful/Beneficial Effects of Odors on Asthma Symptoms
| Registry | NCT02624362 |
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| Status | Enrolling by invitation |
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| Phase | Not applicable |
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| Study type | Interventional; randomized, parallel, masking: none, basic science |
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| Enrollment | 48 (Estimated) |
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| Sponsor | Universitaire Ziekenhuizen KU Leuven (Other); collaborators: KU Leuven, Research Foundation Flanders |
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| Conditions | Asthma |
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| Interventions | Therapeutic Suggestion, Asthmogenic Suggestion, Phenylethyl Alcohol odor (Behavioral, other) |
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| Dates | start 2015-08-01, primary completion 2026-07-01 (estimated), completion 2026-12-01 (estimated), first posted 2015-12-08, last updated 2024-07-03 |
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| Locations | 1 site in Belgium |
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Related Papers Related Patents Related Grants Related Experts
All trials for Asthma All trials of Therapeutic Suggestion All trials of Asthmogenic Suggestion
-Summary
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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+Detailed description
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.
+Arms and interventions
| Arm | Type | Interventions | Description |
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| Odor+ Positive belief | Experimental | Behavioral: Therapeutic Suggestion; Other: Phenylethyl Alcohol odor | Participants receive 15 minute odor presentation (Phenylethyl Alcohol odor) accompanied by the suggestion that this odor improves asthma symptoms (therapeutic suggestion) |
| Odor + Negative belief | Experimental | Behavioral: Asthmogenic Suggestion; Other: Phenylethyl Alcohol odor | Participants receive 15 minute odor presentation (Phenylethyl Alcohol odor) accompanied by the suggestion that this odor worsens asthma symptoms (asthmogenic suggestion) |
- Therapeutic Suggestion (Behavioral), also known as placebo suggestion, positive treatment belief induction: suggestions about potential beneficial effects of the odor are given
- Asthmogenic Suggestion (Behavioral), also known as nocebo suggestion, negative treatment belief: suggestions about potential negative effects of the odor are given
- Phenylethyl Alcohol odor (Other): Over the course of 15 minutes, participants, receive 15 short sniffs of Phenylethyl Alcohol odor
+Outcome measures
Primary outcomes
- Change from Baseline Exhaled Nitric Oxide to 24 hours after odor induction [baseline, immediately after odor induction, 2 hours after odor induction, 24 hours after odor induction]: Fraction of exhaled nitric oxide
Secondary outcomes
- asthma symptoms [baseline, immediately after odor induction, 2 hours after odor induction, 24 hours after odor induction]: measured using the Asthma Symptom Checklist
- Forced Expiratory Volume at one second (FEV1) [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
- Worry [baseline, immediately after odor induction, 2 hours after odor induction, 24 hours after odor induction]: measured using worry Visual Analog Scales
- Cortisol [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
- Change in Heart rate and Heart Rate Variability (HRV) [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.
- Change in Respiratory rate [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
- change in Fraction of end-tidal carbon dioxide (FetCO2) [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
+Eligibility
Sex: All, ages: 18 Years to 65 Years
Inclusion Criteria:
* A physician diagnosis of asthma
Exclusion Criteria:
* FEV1 lower than 60% predicted
* clinical condition other than asthma
+Locations (1)
| Facility | City | Country | Status |
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| UZ Leuven | Leuven | Belgium | |
+Investigators