Objective: Olfactory dysfunction (OD) is a common and distinctive symptom in patients with COVID-19. To date, no standardized treatment for COVID-19-associated OD has been established, but olfactory training (OT) is a promising therapeutic intervention. Previous studies have demonstrated the efficacy of OT in the treatment of postinfectious OD, with several investigations demonstrating the effectiveness of OT in addressing OD associated with COVID-19. In this study, we conducted a retrospective investigation to evaluate the effectiveness of OT and to determine the optimal duration of OT for managing COVID-19-associated OD.
Methods: Patients received an OT kit containing four odorants (rose, eucalyptus, lemon, and clove) and were instructed to sniff each one for 10 seconds, twice daily. To assess olfactory function, participants completed the Self-Administered Odor Questionnaire (SAOQ), Visual Analog Scale for Smell (VAS), T&T olfactometry, and an intravenous olfactory test, which were performed at baseline (pre-OT) and at three post-OT intervals (3 months, 6 months, and 1 year).
Results: Seventeen participants (mean age: 39.7 years, SD: 13) completed the study. Significant improvements were observed in SAOQ, VAS and intravenous olfactory test following OT. Specifically, significant differences were identified between the pre-OT and 1-year post-OT for both SAOQ and VAS (p=0.021, p=0.021, respectively). Additionally, significant differences were noted between the 3-month post-OT and 1-year post-OT for the same measures (p=0.021, p=0.004, respectively). For the intravenous olfactory test, a significant difference was observed in detection time scores between the 3-month post-OT and 6-month post-OT (p=0.031). No significant changes were observed in the T&T olfactometry score.
Conclusion: These findings suggest that OT led to notable enhancements in olfactory function in patients with COVID-19-associated OD. In terms of the duration of OT, our results indicate there are progressive benefits of OT over time.
