Overview
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.
Eligibility
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