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ABSTRACT: Background
Olfactory dysfunction (OD) has been reported in coronavirus disease 2019 (COVID-19). However, there are knowledge gaps about the severity, prevalence, etiology, and duration of OD in COVID-19 patients.Methods
Olfactory function was assessed in all participants using questionnaires and the butanol threshold test (BTT). Patients with COVID-19 and abnormal olfaction were further evaluated using the smell identification test (SIT), sinus imaging, and nasoendoscopy. Selected patients received nasal biopsies. Systematic review was performed according to PRISMA guidelines. PubMed items from January 1, 2020 to April 23, 2020 were searched. Studies that reported clinical data on olfactory disturbances in COVID-19 patients were analyzed.Results
We included 18 COVID-19 patients and 18 controls. Among COVID-19 patients, 12 of 18 (67%) reported olfactory symptoms and OD was confirmed in 6 patients by BTT and SIT. Olfactory dysfunction was the only symptom in 2 patients. Mean BTT score of patients was worse than controls (P = .004, difference in means = 1.8; 95% confidence interval, 0.6-2.9). Sinusitis and olfactory cleft obstruction were absent in most patients. Immunohistochemical analysis of nasal biopsy revealed the presence of infiltrative CD68+ macrophages harboring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen in the stroma. Olfactory dysfunction persisted in 2 patients despite clinical recovery. Systematic review showed that the prevalence of olfactory disturbances in COVID-19 ranged from 5% to 98%. Most studies did not assess olfaction quantitatively.Conclusions
Olfactory dysfunction is common in COVID-19 and may be the only symptom. Coronavirus disease 2019-related OD can be severe and prolonged. Mucosal infiltration by CD68+ macrophages expressing SARS-CoV-2 viral antigen may contribute to COVID-19-related OD.
SUBMITTER: Chung TW
PROVIDER: S-EPMC7284010 | biostudies-literature | 2020 Jun
REPOSITORIES: biostudies-literature
Chung Tom Wai-Hin TW Sridhar Siddharth S Zhang Anna Jinxia AJ Chan Kwok-Hung KH Li Hang-Long HL Wong Fergus Kai-Chuen FK Ng Ming-Yen MY Tsang Raymond King-Yin RK Lee Andrew Chak-Yiu AC Fan Zhimeng Z Ho Ronnie Siu-Lun RS Luk Shiobhon Yiu SY Kan Wai-Kuen WK Lam Sonia Hiu-Yin SH Wu Alan Ka-Lun AK Leung Sau-Man SM Chan Wai-Ming WM Ng Pauline Yeung PY To Kelvin Kai-Wang KK Cheng Vincent Chi-Chung VC Lung Kwok-Cheung KC Hung Ivan Fan-Ngai IF Yuen Kwok-Yung KY
Open forum infectious diseases 20200605 6
<h4>Background</h4>Olfactory dysfunction (OD) has been reported in coronavirus disease 2019 (COVID-19). However, there are knowledge gaps about the severity, prevalence, etiology, and duration of OD in COVID-19 patients.<h4>Methods</h4>Olfactory function was assessed in all participants using questionnaires and the butanol threshold test (BTT). Patients with COVID-19 and abnormal olfaction were further evaluated using the smell identification test (SIT), sinus imaging, and nasoendoscopy. Selecte ...[more]