(347) Olfactory Training in C19OD vs Non-COVID-19 PIOD

Introduction: Studies in the early stages of the COVID-19 pandemic have evaluated olfactory and gustatory symptoms using subjective surveys and simple olfactory tests only. We compared the olfactory and gustatory characteristics of patient groups with COVID-19 Olfactory Dysfunction (C19OD) and non-COVID-19 Postinfectious Olfactory Dysfunction (PIOD) using an objective olfactory test and evaluated the significance of olfactory training in both patient groups.

Methods: We retrospectively analyzed the medical records of 14 patients with decreased sense of smell after Confirming COVID-19 PCR and 56 patients with PIOD without a history of confirmed COVID-19 from March 2015 to December 2019. Patients with a history of chronic sinusitis, nasal surgery, hypothyroidism, liver cirrhosis, malignant tumor, or head trauma were excluded from the study. Participants were evaluated for KVSS-II and chemical gustometry at the time of their first visit. All participants performed olfactory training after the first visit and were reevaluated after an average of 8(± 6) weeks.

Results: The average age of participants in the C19OD group was lower than in those in the non-COVID-19 group (P < 0.001). The proportion of men in the C19OD group was higher than in the non-COVID-19 PIOD group (P=0.005). At baseline assessment, the C19OD group had better olfactory and gustatory functions. After olfactory training, the non-COVID-19 PIOD patient group showed a significant increase in all KVSS-II Total (P < 0.001), T (P < 0.001), D (P < 0.008) , and I (P < 0.001) scores, but there was a non-significant increase in all scores in the C19OD group.

Conclusions: The C19OD group had better olfactory and gustatory function than the non-COVID-19 PIOD group at the initial assessment. After olfactory training, there was an increase in olfactory function test scores in both groups. Olfactory training may be helpful in C19OD, as in non-COVID-19 PIOD.