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

NCT06829706 | Recruiting DMC

• 1 other identifier: 9059103
• Study Type: interventional
• Target: 150
• Locations: 1 country
• Sites: 1

Brief Summary

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?

Conditions

Olfactory Dysfunction; Post Viral Olfactory Dysfunction (PVOD)

Keywords

Olfactory Training; Modified Olfactory Training Device; Post Viral Olfactory Dysfunction (PVOD)

Outcome Measures

Primary Outcomes (1)

• The total scores in the "Sniffin 'Sticks" test

  This olfactory test consists of three subtests that respectively measure odor threshold (T), odor discrimination (D), and odor identification (I). Each subtest has a maximum score of 16, and the sum of the scores from the three subtests provides the global olfactory score (TDI score; Threshold, Discrimination, Identification) with a maximum of 48 points. Patients with a TDI composite score≥30.5 are defined as normosmic. In contrast, those with a TDI composite score between 16.5 and 30.5 are defined as hyposmic, and patients with a TDI composite score\<16.5 are defined as functionally anosmic. Based on previous literature, we have established a 5.5 points improvement in the TDI composite score as a significant change.

  Baseline,Month 3,Month 6,Month 12,Month 24

Secondary Outcomes (7)

• OB volume and shape measurement

  Baseline,Month 3,Month 6,Month 12,Month 24

• MRI volumetric evaluation related to GM

  Baseline,Month 3,Month 6,Month 12,Month 24

• MRI volumetric evaluation related to WM

  Baseline,Month 3,Month 6,Month 12,Month 24

• MRI volumetric evaluation related to CSF

  Baseline,Month 3,Month 6,Month 12,Month 24

• Event-related potentials (ERPs)

  Baseline,Month 3,Month 6,Month 12,Month 24

Study Arms (3)

The Conventional olfactory training

ACTIVE COMPARATOR

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.

Device: Conventional olfactory training device

The Control group

SHAM COMPARATOR

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.

Device: Conventional olfactory training device with placebo

The Modified olfactory training

EXPERIMENTAL

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.

Device: Modified olfactory training device

Interventions

Conventional olfactory training device 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 Conventional olfactory training

Modified olfactory training device 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.

The Modified olfactory training

Conventional olfactory training device with placebo DEVICE

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

The Control group

Eligibility Criteria

• Age: 18 Years - 80 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

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

You may not qualify if:

• Patients with post-traumatic olfactory dysfunction, rhinosinusitis-related dysfunction and olfactory dysfunction caused by other reasons.
• Patients with concomitant sinonasal disease.
• Patients with chronic diseases, such as hypertension, diabetes, bronchopneumonia, chronic obstructive pulmonary disease, etc.
• Patients with serious coexisting diseases: such as malignant tumors, etc., with a life expectancy of less than 2 years.
• Patients who cannot tolerate olfactory function testing and treatment.
• Patients who have taken oral glucocorticoids, antibacterial drugs, anti-leukotrienes, antihistamines, or received olfactory training within four weeks will be excluded.
• Patients who are receiving treatment that affects olfactory recovery.
• Patients with smoking habits.
• Patients who are already or plan to be pregnant.
• 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).
• Patients who did not consent for participating in the study.

Sponsors & Collaborators

• Peking University Third Hospital: lead

Study Sites (1)

Bejing

Beijing, 100191, China

RECRUITING

Related Publications (1)

• Xie J, Li Y, He H, Liu Y, Chen L, Liu X, Zhao D, Wu D. Randomised trial protocol to assess efficacy of modified olfactory training method for patients with postinfectious olfactory dysfunction. BMJ Open. 2025 Dec 23;15(12):e101183. doi: 10.1136/bmjopen-2025-101183.

  PMID: 41436263 DERIVED

Central Study Contacts

Dawei Wu, MD, PhD

CONTACT

13522503401; davidwuorl@163.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Researcher

Study Record Dates

• First Submitted: February 6, 2025
• First Posted: February 17, 2025
• Study Start: March 22, 2025
• Primary Completion (Estimated): March 22, 2027
• Study Completion (Estimated): May 22, 2027
• Last Updated: February 17, 2025

Record last verified: 2025-02

Data Sharing

• IPD Sharing: Will not share

Locations

CN (1)