Prevalence and Factors Associated with Olfactory Dysfunction in Individuals with COVID-19 in Brazil: A Study of 20,669 Cases from 2020 to 2021.

Abstract

Objective: The aim of the study is to determine the prevalence and factors associated with olfactory dysfunction in individuals with COVID-19 in the first 2 years of the pandemic in Brazil.

Materials and methods: This is a prevalent study involving the confirmed cases of COVID-19 recorded in the municipality between the years 2020 and 2021. Individuals symptomatic for COVID-19, with a positive laboratory result and aged 12 or older were included in this study. Measures of central tendency and dispersion were used in the description of continuous variables and frequency was used for categorical variables. The Shapiro-Wilk test was used to evaluate data distribution.

Results: Data from 20,669 individuals were analyzed. The prevalence of olfactory disorders was 17.9% and increased from 11.5% to 21.9% between 2020 and 2021. A female gender predominance was observed among individuals who reported anosmia, with 61.1% (n = 564) in 2020 and 61.7% (n = 1,713) in 2021. On the other hand, the median age of individuals with olfactory disorders was lower than that of the group without disorders (35 [IQR 27-46] vs. 39 [IQR 29-50]; p < 0.001). Smell disturbances were present in 18.2% (n = 3,634) of patients who recovered and in 7.1% (n = 38) of those who died. Furthermore, in 2021, a prevalence rate of 30.6% for olfactory disorders was linked to obesity as a comorbidity.

Conclusion: The prevalence of olfactory disorders was lower compared to other studies, with cough and fever being negatively related to olfactory dysfunction and headache, coryza, and taste disorders being positively related. Obesity was the only associated comorbidity.