The Effect of Olfactory Training in Patients With COVID-19 Induced Olfactory Dysfunction

NCT ID: NCT05539560

Last Updated: 2024-09-23

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

NA

Total Enrollment

65 participants

Study Classification

INTERVENTIONAL

Study Start Date

2022-06-29

Study Completion Date

2025-09-30

Brief Summary

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Aim: The aim is to investigate the effect of olfactory training with essential oils versus olfactory training with placebo-oils in patients with COVID-19 induced olfactory dysfunction

Study design: The study is a placebo-controlled randomized clinical trial with an intervention group and a control group. The intervention group receive four essential oils with scents of orange, lavender, clove, and peppermint. Patients in the control group receive a fragrance kit, consisting of the same containers, but with fragrance-free oils added. Both groups are instructed to smell each of the four oils for 30 seconds in the morning and evening, over a three-month intervention period. Patients are given a diary in which to record their olfactory training. The nurse or medical student instructing the patients in the training and performing the smell and taste tests is blinded.

Study population: Patients referred to the Unit for Sense of Taste and Smell in the Department of Otorhinolaryngology Head \& Neck and Audiology at Rigshospitalet.

Inclusion criteria:

* Impaired sense of taste and smell following COVID-19 \> 3 months
* Hyposmia (16.25-30.5) or anosmia (\<16) assessed by Sniffin' Sticks Olfactory Test for Threshold, Discrimination and Identification (TDI) performed in the Unit for Sense of Taste and Smell with or without parosmia based on medical history
* \> 18 years of age

Exclusion criteria:

* Cause of hyposmia, anosmia or parosmia other than COVID-19
* Does not read or speak Danish
* Lack of compliance to perform daily olfactory training

Procedures:

\- TDI-test: To assess patients' sense of smell, the TDI-test with Sniffin' Sticks is used, which is a validated tool with normative data.

Questionnaires:

\- 'Taste and Smell Tool for Evaluation' is used to investigate quality of life related to impaired sense of taste and smell.

Detailed Description

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Conditions

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COVID-19

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

TREATMENT

Blinding Strategy

QUADRUPLE

Participants Caregivers Investigators Outcome Assessors

Study Groups

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Intervention group

Olfactory training twice a day with essential oils

Group Type EXPERIMENTAL

Olfactory training with essential oils

Intervention Type OTHER

Olfactory training twice daily with essential oils from Urtegaarden Aps with scents of orange, lavender, clove and peppermint. The olfactory training is performed every morning and evening, by smelling each of the oils for 30 seconds.

Control group

Olfactory training twice a day with fragrance-free oils

Group Type PLACEBO_COMPARATOR

Olfactory training with fragrance-free oils

Intervention Type OTHER

Olfactory training twice daily with fragrance-free oils from Urtegaarden Aps in the same four containers as the intervention group. The olfactory training is performed every morning and evening, by smelling each of the oils for 30 seconds.

Interventions

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Olfactory training with essential oils

Olfactory training twice daily with essential oils from Urtegaarden Aps with scents of orange, lavender, clove and peppermint. The olfactory training is performed every morning and evening, by smelling each of the oils for 30 seconds.

Intervention Type OTHER

Olfactory training with fragrance-free oils

Olfactory training twice daily with fragrance-free oils from Urtegaarden Aps in the same four containers as the intervention group. The olfactory training is performed every morning and evening, by smelling each of the oils for 30 seconds.

Intervention Type OTHER

Other Intervention Names

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Urtegaarden ApS Essential Oils Urtegaarden ApS Essential Oils (Fragrance-free custom made)

Eligibility Criteria

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Inclusion Criteria

* Olfactory dysfunction caused by COVID-19
* Hyposmia (16.25-30.5) or anosmia (\<16) with or without parosmia assessed by TDI test with Sniffin Sticks performed in the Unit for Sense of Taste and Smell
* \> 18 years of age

Exclusion Criteria

* Cause of hyposmia, anosmia or parosmia other than COVID-19
* Does not read or speak Danish
* Lack of compliance to perform daily olfactory training
Minimum Eligible Age

18 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Ditte Gertz Mogensen

OTHER

Sponsor Role lead

Responsible Party

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Ditte Gertz Mogensen

PhD-student

Responsibility Role SPONSOR_INVESTIGATOR

Principal Investigators

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Vibeke G Backer, Professor

Role: STUDY_CHAIR

Rigshospitalet, Denmark

Locations

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Department of Otorhinolaryngology, Head and Neck Surgery & Audiology, Copenhagen University Hospital

Copenhagen, , Denmark

Site Status RECRUITING

Countries

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Denmark

Central Contacts

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Ditte G Gertz Mogensen, PhD-student

Role: CONTACT

+45 35457508

Vibeke Backer, Professor

Role: CONTACT

+45 35456033

Facility Contacts

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Ditte Gertz Mogensen, PhD-student

Role: primary

+45 35457508

Vibeke Backer, Professor

Role: backup

+45 3545 6033

References

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Mogensen DG, Aanaes K, Andersen IB, Jarden M, Backer V. Effect of Olfactory Training in COVID-19 Related Olfactory Dysfunction-A Placebo-Controlled Trial. Laryngoscope. 2025 May 15. doi: 10.1002/lary.32275. Online ahead of print.

Reference Type DERIVED
PMID: 40371997 (View on PubMed)

Provided Documents

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Document Type: Study Protocol, Statistical Analysis Plan, and Informed Consent Form

View Document

Other Identifiers

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2022-ENT-1-olfactory

Identifier Type: -

Identifier Source: org_study_id

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