Epidemiological, otolaryngological, olfactory and gustatory outcomes according to the severity of COVID-19: a study of 2579 patients.

Objective: To investigate prevalence and epidemiological and clinical factors associated with olfactory dysfunction (OD) and gustatory dysfunction (GD) in COVID-19 patients according to the disease severity.
Study Design: Cross-sectional study.
Methods: A total of 2579 patients with a positive diagnosis of COVID-19 were identified between March 22 and June 3, 2020 from 18 European hospitals. Epidemiological and clinical data were extracted. Otolaryngological symptoms, including OD and GD, were collected through patient-reported outcome questionnaire and Sniffin'Sticks tests were carried out in a subset of patients.
Results: A total of 2579 patients were included, including 2166 mild (84.0%), 144 moderate (5.6%) and 269 severe-to-critical (10.4%) patients. Mild patients presented an otolaryngological picture of the disease with OD, GD, nasal obstruction, rhinorrhea and sore throat as the most prevalent symptoms. The prevalence of subjective OD and GD was 73.7 and 46.8%, and decreases with the severity of the disease. Females had higher prevalence of subjective OD and GD compared with males. Diabetes was associated with a higher risk to develop GD. Among the subset of patients who benefited from psychophysical olfactory evaluations, there were 75 anosmic, 43 hyposmic and 113 normosmic patients. The prevalence of anosmia significantly decreased with the severity of the disease. Anosmia or hyposmia were not associated with any nasal disorder, according to SNOT-22.
Conclusion: OD and GD are more prevalent in patients with mild COVID-19 compared with individuals with moderate, severe or critical diseases. Females might have a higher risk of developing OD and GD compared with males.