The Effectiveness of Steroid Nasal Drops in the Olfactory Cleft Combined With Olfactory Training for Patients With PIOD

Post-infectious olfactory dysfunction (PIOD) is a prevalent condition, particularly following viral upper respiratory infections such as COVID-19, and significantly impacts patients' quality of life. Current treatments primarily rely on olfactory training, but its effectiveness varies, with improvement rates ranging between 30% and 50%. Emerging evidence suggests that olfactory cleft obstruction and chronic inflammation play critical roles in PIOD pathogenesis, highlighting the potential benefits of targeted steroid therapy to address these underlying mechanisms.

In this study, the investigators planned to recruit 100 patients and divided them into two groups for combined therapy with steroid drops or placebo drops alongside olfactory training, and validate the effectiveness of the combined therapy based on the comparison of the outcomes of the two groups.

• Steroid nasal drops combined with olfactory training (Combination product): The intervention consists of two components: steroid nasal drops and modified olfactory training.
• Placebo nasal drops combined with olfactory training (Combination product): The intervention consists of two components: normal saline nasal drops and modified olfactory training.

Primary outcomes

• The Sniffin' Sticks test [Baseline, 1 week, 4 weeks, 8 weeks, and 12 weeks after the initiation of treatment.]: A clinically significant olfactory improvement as measured by Sniffin' Sticks threshold, discrimination, and identification(TDI)

Secondary outcomes

• Questionnaire of Olfactory Disorders - Negative Statements (QOD-NS) [Baseline, 2 weeks, 4 weeks, 8 weeks, and 12 weeks after the initiation of treatment.]: The QOD-NS includes 17 negative statements, each graded from 0 (disagree) to 3 (agree) for a maximum score of 51. Higher QOD-NS scores reflect worse QoL.
• Olfactory-Visual Analogue Scale (VAS) [Baseline, 2 weeks, 4 weeks, 8 weeks, and 12 weeks after the initiation of treatment.]: Subjects rate the impact of smell loss on their mood, ability to enjoy food, social interactions, safety, personal hygiene, sex life, ability to cook food, appetite and change in weight from 0 (no impact) to 10 (most impact) for a maximum score of 90. Higher olfactory-VAS scores reflect more severe impacts on daily life.
• CT Evaluation of Olfactory Cleft Blockage [Baseline and 12 weeks after the initiation of treatment.]: The olfactory cleft was divided into anterior and posterior, divided by the anterior end of the superior turbinate. The anterior and posterior olfactory cleft opacifications were graded separately on a scale of 0-4 by the ratio of the opacified area to the whole area of the olfactory cleft, with 0 (no opacification), 1 (25%), 2 (25%-50%), 3 (50%-75%), and 4 (>75%). The olfactory cleft CT score, calculated as the sum of the anterior and posterior olfactory cleft scores, ranged from 1 to 8 (Kim DW, Kim JY, Jeon SY. The status of the olfactory cleft may predict postoperative olfactory function in chronic rhinosinusitis with nasal polyposis. Am J Rhinol Allergy. 2011;25(2):e90-4.).
• Inflammatory Marker Levels in Olfactory Mucosa [Baseline and 12 weeks after the initiation of treatment.]: Analysis of inflammatory cytokines （IL-4、IL-5、IL-13、IL-25、IL-33 and TSLP）via ELISA and single-cell sequencing from olfactory mucosal brush samples.
• Plasma Cortisol Levels [Baseline and 12 weeks after the initiation of treatment.]: Measurement of systemic cortisol concentrations through venous blood sampling
• Adverse Event [2 weeks, and 4 weeks, 8 weeks, and 12 weeks after the initiation of treatment.]: Documentation of local (nasal irritation, epistaxis) and systemic steroid-related adverse events using standardized case report forms during all follow-up visits.

Sex: All, ages: 18 Years to 65 Years

Inclusion Criteria:

1. Prospective enrollment of otolaryngology clinic patients aged 18-65 years with olfactory dysfunction. Diagnosis of post-infectious olfactory dysfunction (PIOD) will be based on the PPOD 2023 criteria. Participants must demonstrate olfactory impairment via Sniffin' Sticks testing, with TDI scores (sum of Threshold, Discrimination, and Identification) meeting: (1) Hyposmia: 16 < TDI < 30.75; (2) Anosmia: TDI ≤ 15.
2. Willingness to participate and signed informed consent.

Exclusion Criteria:

1. Use of systemic corticosteroids within 4 weeks or intranasal steroids within 2 weeks prior to enrollment.
2. Severe nasal septum deviation, nasal tumors, acute upper respiratory infections, or uncontrolled allergic rhinitis.
3. History of functional endoscopic sinus surgery or other nasal procedures within 12 months.
4. Severe cardiovascular disease, hepatic/renal insufficiency, uncontrolled diabetes, or immune system disorders.
5. Current or planned pregnancy.
6. Investigator-determined inability to comply with study requirements (e.g., memory/behavioral disorders, depression, heavy alcohol use, prior non-compliance).