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Nemati S, Faghih Habibi A, Shalchizadeh M, Yaghubi Kalurazi T, Balou H A, Mashouf M, et al . Olfactory Dysfunction and Phantosmia in Patients With COVID-19 in Northern Iran. Caspian J Neurol Sci 2022; 8 (3) :171-177
URL: http://cjns.gums.ac.ir/article-1-548-fa.html

Background: One of the most common symptoms of COVID-19 infection is Olfactory Dysfunction (OD).
Objectives: This study aims to investigate OD and phantosmia in COVID-19 cases from northern Iran.
Materials & Methods: In this cross-sectional study, participants were 400 patients with COVID-19 infection in Rasht, Iran from March 2019 to September 2020. All the patients were evaluated in terms of OD and then followed up for 3 months face-to-face, by telephone call, or online.
Results: Among 400 patients, 37.75% had OD (19% hyposmia, 10.75% primary phantosmia, and 8% anosmia) during the initiation of the disease, but 121 (30.25%) including nearly 65% of anosmic and/or hyposmic cases reported phantosmia at different time intervals of followup visits. Moreover, 65.38% of patients reported acute onset of OD. The prevalence of OD was significantly higher in patients aged <40 years (P=0.001) and in females (P=0.002). OD improved in about 90% of patients within 3 months. Peripheral oxygen saturation was better in anosmic cases and C-reactive protein level was higher in normosmic cases at their first visit. No significant difference was found in terms of other laboratory results.
Conclusion: OD is a common complication of COVID-19 infection, but seems not to be permanent. It is more common in young patients, females, and those with mild COVID-19 infection.