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

Peking University

Status: Enrolling

Conditions: Olfactory Dysfunction; Post Viral Olfactory Dysfunction (PVOD)

Treatments: Device: Modified olfactory training device; Device: Conventional olfactory training device; Device: Conventional olfactory training device with placebo

Study type: Interventional

Funder types: Other

Identifiers

NCT06829706

9059103

Details and patient eligibility

About

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?

Full description

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.

Enrollment: 150 estimated patients

Sex: All

Ages: 18 to 80 years old

Volunteers: No Healthy Volunteers

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.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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150 participants in 3 patient groups

The Conventional olfactory training

Active Comparator group

Description:

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.

Treatment:

Device: Conventional olfactory training device

The Control group

Sham Comparator group

Description:

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.

Treatment:

Device: Conventional olfactory training device with placebo

The Modified olfactory training

Experimental group

Description:

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.

Treatment:

Device: Modified olfactory training device