The Efficacy of Modified Olfactory Training Method for Patients With Post-viral Olfactory Dysfunction

NCT ID: NCT06829706

Last Updated: 2025-02-17

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

150 participants

Study Classification

INTERVENTIONAL

Study Start Date

2025-03-22

Study Completion Date

2027-05-22

Brief Summary

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The goal of this clinical trial is to validate the effectiveness of the modified olfactory training device, the main questions it aims to answer are: Is the modified olfactory training device effective in treating patients with post-viral olfactory dysfunction? Compared to the conventional device, how efficient is the modified olfactory training device for improving olfactory function?

Detailed Description

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Background The aim of this article is to present the research protocol for a randomized, controlled, multi-center, placebo study that will assess the olfactory function and the effect of an intervention based on olfactory training in patients with post-viral olfactory dysfunction, and compare it with traditional olfactory training. The sample selection will follow the multi-center principle. The olfactory training (OT) intervention will last for 12 weeks.

Evaluation The primary endpoint will be the change in olfactory ability from baseline to the 12-week intervention or control period. The intervention effect will be evaluated by the total score of the Sniffer Stick Test (SST)-Threshold, Discrimination and Identification (TDI)-Extended Version. Secondary endpoints will be changes in olfactory bulb volume and shape, olfactory-related brain area volume, olfactory and trigeminal nerve-related potentials, and cognitive questionnaires.

Conclusion(objective) The present study aimed to explore the efficacy of the modified olfactory training device (MOT), and compare COT and MOT with respect to the resultant improvement in olfactory function.

At the same time, our study will use a variety of outcome indicators to evaluate the changes in patients before and after treatment, which will lay the foundation for exploring the mechanism of olfactory training in treating patients with post-viral olfactory disorders.

Conditions

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Olfactory Dysfunction Post Viral Olfactory Dysfunction (PVOD)

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

TREATMENT

Blinding Strategy

DOUBLE

Investigators Outcome Assessors

Study Groups

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The Conventional olfactory training

Patients allocated to the COT group are told to expose themselves twice daily to four odors (phenyl ethyl alcohol: rose, menthol: mint, citronellal: lemon, and eugenol: cloves),which are placed in four brown glass jars (total volume 50 mL) with one of the four odors in each (1 mL each, soaked in cotton pads to prevent spilling). All jars are labeled with the odor name.

Olfactory training includes exposure to odorants twice per day for 5 minutes. Every olfactory session included rotated exposure to each odorant for 10 seconds each, with time intervals of 10 seconds between odors. The resting order of the four odors is mint-rose-lemon-clove.

Patients were advised to sniff the odors in the morning before breakfast and in the evening before bedtime.

Group Type ACTIVE_COMPARATOR

Conventional olfactory training device

Intervention Type DEVICE

Conventional olfactory training was designed by Hummel et al. They performed OT using four odors (phenyl ethyl alcohol, rose; eucalyptol, eucalyptus; citronella, lemon; and eugenol, cloves), which are representative of four odor categories on the odor prism proposed by Henning.

The Control group

The COT group will differ solely with regard to the ingredients contained in the training jars given to the participants. Whereas in the COT group, the training jars will contain the active odors previously selected, in the placebo group, the training jars will be filled with a placebo odorless solvent (propylene glycol). To increase the overall compliance and to ascertain that the placebo (odorless) group remains blinded to the treatment allocation, all patients are told that whereas the odors used during the therapy tend to be less strong, and may be insufficiently intense to produce an odor sensation (i.e., subliminal odors), they are intense enough to be perceived by the brain and may influence mental processes and behavior. The training will last for 12 weeks. After the study completion, all participants will be individually contacted and their group allocations will be revealed. All patients will be offered the possibility of performing or continuing a training with odors.

Group Type SHAM_COMPARATOR

Conventional olfactory training device with placebo

Intervention Type DEVICE

Based on the traditional olfactory training device, four olfactory odors are replaced by placebo。

The Modified olfactory training

When the patient is doing olfactory training, he/she selects an odor and installs the corresponding odor bottle on the new olfactory training device. Insert the nose end into one nostril, hold the mouth end in the mouth, take a deep breath through the nose, blow out slowly for about 7 seconds, and carefully experience the changes in the nature and intensity of the nasal odor. Immediately remove the device from the nostril and mouth, take a slow, natural breath through the nose for about 3 seconds; Repeat the above operation for a total of three cycles. The operation steps for the other nostril are the same as those above. When both nostrils have finished sniffing the same odor, stop the training, breathe freely, and rest for 10 seconds. Then continue to sniff the next odor and train in the order and method described above.

Accordingly, all odors used for the application of MOT were identical to the COT method in terms of the duration and application time of each session.

Group Type EXPERIMENTAL

Modified olfactory training device

Intervention Type DEVICE

Participants will use a modified olfactory training device based on expiratory pressure. Its bidirectional airflow and unidirectional pressure characteristics significantly increased the deposition rate of olfactory odors in the olfactory cleft area, making the patient feel stronger in the nasal cavity during olfactory training.

Interventions

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Conventional olfactory training device

Conventional olfactory training was designed by Hummel et al. They performed OT using four odors (phenyl ethyl alcohol, rose; eucalyptol, eucalyptus; citronella, lemon; and eugenol, cloves), which are representative of four odor categories on the odor prism proposed by Henning.

Intervention Type DEVICE

Modified olfactory training device

Participants will use a modified olfactory training device based on expiratory pressure. Its bidirectional airflow and unidirectional pressure characteristics significantly increased the deposition rate of olfactory odors in the olfactory cleft area, making the patient feel stronger in the nasal cavity during olfactory training.

Intervention Type DEVICE

Conventional olfactory training device with placebo

Based on the traditional olfactory training device, four olfactory odors are replaced by placebo。

Intervention Type DEVICE

Eligibility Criteria

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Inclusion Criteria

1. Age 18-80 years old, gender not limited.
2. Patients diagnosed with olfactory dysfunction following infections of the upper respiratory tract, as determined by Sniffin' Sticks test (including TDI value test).
3. Voluntarily signs the informed consent form.

Exclusion Criteria

1. Patients with post-traumatic olfactory dysfunction, rhinosinusitis-related dysfunction and olfactory dysfunction caused by other reasons.
2. Patients with concomitant sinonasal disease.
3. Patients with chronic diseases, such as hypertension, diabetes, bronchopneumonia, chronic obstructive pulmonary disease, etc.
4. Patients with serious coexisting diseases: such as malignant tumors, etc., with a life expectancy of less than 2 years.
5. Patients who cannot tolerate olfactory function testing and treatment.
6. Patients who have taken oral glucocorticoids, antibacterial drugs, anti-leukotrienes, antihistamines, or received olfactory training within four weeks will be excluded.
7. Patients who are receiving treatment that affects olfactory recovery.
8. Patients with smoking habits.
9. Patients who are already or plan to be pregnant.
10. According to the judgment of the researchers, the patient cannot complete this study or cannot comply with the requirements of this study (such as memory or behavior abnormalities, depression, heavy drinking, previous breach of contract).
11. Patients who did not consent for participating in the study.
Minimum Eligible Age

18 Years

Maximum Eligible Age

80 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Peking University Third Hospital

OTHER

Sponsor Role lead

Responsible Party

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Dawei Wu

Associate Researcher

Responsibility Role PRINCIPAL_INVESTIGATOR

Locations

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Bejing

Beijing, , China

Site Status RECRUITING

Countries

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China

Central Contacts

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Dawei Wu, MD, PhD

Role: CONTACT

13522503401

Facility Contacts

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Dawei Wu, MD, PhD

Role: primary

13522503401

Other Identifiers

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9059103

Identifier Type: -

Identifier Source: org_study_id

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