The Effect of Olfactory Training in Patients With COVID-19 Induced Olfactory Dysfunction (SMELLT2022)

September 19, 2024 updated by: Ditte Gertz Mogensen

The Effect of Olfactory Training in Patients With COVID-19 Induced Olfactory Dysfunction - A Randomized Placebo-controlled Clinical Trial

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.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

65

Phase

  • Not Applicable

Contacts and Locations

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

Study Contact

Study Contact Backup

Study Locations

  • Denmark
      • Copenhagen, Denmark, 2100
        • Recruiting
        • Department of Otorhinolaryngology, Head and Neck Surgery & Audiology, Copenhagen University Hospital
        • Contact:
        • Contact:

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

14 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

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

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

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Intervention group
Olfactory training twice a day with essential oils
Other: 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.
Other Names:
  • Urtegaarden ApS Essential Oils
Placebo Comparator: Control group
Olfactory training twice a day with fragrance-free oils
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.
Other Names:
  • Urtegaarden ApS Essential Oils (Fragrance-free custom made)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Extended Sniffin' Sticks Test score
Time Frame: 3 months follow-up
Change in TDI score measured by Burghart Extended Sniffin' Sticks Test (TDI test). The TDI test, consists of a threshold test, a discrimination test, and an identification test. The results of the three subtests makes a total TDI score, where the minimum score is 1 and the maximum score is 48. A score >30 indicates normal olfactory function, a score between 15-30 indicates hyposmia and a score <15 indicates anosmia in the form of severely impaired or complete loss of olfaction.
3 months follow-up

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Quality of Life
Time Frame: 3 months follow-up
Change in Quality of Life measured by the questionnaire Taste and Smell Tool for Evaluation. The minimum score is 21 and the maximum score is 105. A higher score means worse outcome (quality of life).
3 months follow-up

Collaborators and Investigators

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

Sponsor

Ditte Gertz Mogensen

Investigators

  • Study Chair: Vibeke G Backer, Professor, Rigshospitalet, Denmark

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)

June 29, 2022

Primary Completion (Actual)

April 30, 2024

Study Completion (Estimated)

September 30, 2025

Study Registration Dates

First Submitted

September 2, 2022

First Submitted That Met QC Criteria

September 13, 2022

First Posted (Actual)

September 14, 2022

Study Record Updates

Last Update Posted (Actual)

September 23, 2024

Last Update Submitted That Met QC Criteria

September 19, 2024

Last Verified

September 1, 2024

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2022-ENT-1-olfactory

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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