Intensive Olfactory Training in Post-COVID-19 Patients: A Multicenter Randomized Clinical Trial

Area of Science:

• Neurology
• Otolaryngology
• Infectious Diseases

Background:

• Olfactory dysfunction (OD) is a frequent symptom following COVID-19.
• Olfactory training (OT) is a recognized treatment for post-infectious OD.
• Optimizing OT protocols for SARS-CoV-2 related OD requires further investigation.

Purpose of the Study:

• To evaluate if increasing fragrance variety in OT enhances outcomes for persistent post-COVID OD.
• To determine if a shorter, more intensive OT period is superior to standard protocols.
• To identify factors influencing OD and treatment response in COVID-19 survivors.

Main Methods:

• A multicenter randomized clinical trial involving 80 patients with recent persistent OD post-COVID-19.
• Patients were randomized into two groups: one using 4 essences, the other using 8 essences over 4 weeks.
• Olfactory function was assessed using subjective reports and the University of Pennsylvania Smell Identification Test (UPSIT) pre- and post-intervention.

Main Results:

• Both training protocols resulted in significant subjective and objective olfactory improvements.
• No statistically significant difference in olfactory improvement was found between the 4-essence and 8-essence groups.
• Olfactory fluctuations correlated positively with higher UPSIT scores, suggesting a potential indicator of olfactory status.

Conclusions:

• Intensifying olfactory training by increasing the number of essences over 4 weeks offers no advantage over standard methods for post-COVID OD.
• Standard olfactory training protocols remain effective for managing olfactory dysfunction after SARS-CoV-2 infection.
• Fluctuating olfaction may be associated with better performance on smell identification tests.