Association Between Smell Training and Quality of Life in Patients With Impaired Sense of Smell Following COVID-19

Study Overview
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Brief Summary
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Aim: The aim is to investigate whether guided systematic olfactory training with essential oils to improve impaired sense of smell following COVID-19, can improve patients' quality of life. Hypothesis: The impaired quality of life in patients with impaired sense of smell following COVID-19, can be significantly improved in patients performing olfactory training with essential oils, compared to patients performing olfactory training with placebo oils. Study design: The study is a 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 (15-30) or anosmia (<15) assessed by Sniffin' Sticks Olfactory Test for Threshold, Discrimination and Identification (TDI) performed in the Unit for Sense of Taste and Smell or medical assessment of parosmia based on medical history > 18 years of age Exclusion criteria: Cause of hyposmia, anosmia or parosmia other than COVID-19 Impaired sense of taste and smell >24 months 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. Taste test: To assess patients' sense of taste, taste sprays with the basic tastes are used. Questionnaires: 'Taste and Smell Tool for Evaluation' is used to investigate quality of life related to impaired sense of taste and smell. 'Major Depression Inventory' (MDI) is used in the project to assess whether the patient is depressed and to make a possible assessment of the severity of depression.

Official Title
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Association Between Olfactory Training and Quality of Life in Patients With Impaired Sense of Taste and Smell Following COVID-19

Conditions
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COVID-19

Intervention / Treatment
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* Other: Olfactory training with essential oils
* Other: Olfactory training with fragrance-free oils


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Olfactory dysfunction caused by COVID-1 Hyposmia (15-30) or anosmia (<15) assessed by TDI test with Sniffin Sticks performed in the Unit for Sense of Taste and Smell or medical assessment of 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

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Intervention group<br>Olfactory training twice a day with essential oils | Other: Olfactory training with essential oils<br>* 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.<br>* Other names: Urtegaarden ApS Essential Oils;|
| Placebo Comparator: Control group<br>Olfactory training twice a day with fragrance-free oils | Other: Olfactory training with fragrance-free oils<br>* 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.<br>* Other names: Urtegaarden ApS Essential Oils (Fragrance-free custom made);|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Quality of Life | 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 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Extended Sniffin' Sticks Test score | 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 | 
| Change in Major Depression Inventory score (MDI) | Change in MDI score measured by Major Depression Inventory. The theoretical sum score ranges from 0 (no depression) to 50 (maximum depression). | 3 months follow-up | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Olfactory training, Quality of life, Olfactory dysfunction, Covid-19