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Olfactory Dysfunction in Coronavirus Disease 2019 Patients: Observational Cohort Study and Systematic Review.
Chung, Tom Wai-Hin; Sridhar, Siddharth; Zhang, Anna Jinxia; Chan, Kwok-Hung; Li, Hang-Long; Wong, Fergus Kai-Chuen; Ng, Ming-Yen; Tsang, Raymond King-Yin; Lee, Andrew Chak-Yiu; Fan, Zhimeng; Ho, Ronnie Siu-Lun; Luk, Shiobhon Yiu; Kan, Wai-Kuen; Lam, Sonia Hiu-Yin; Wu, Alan Ka-Lun; Leung, Sau-Man; Chan, Wai-Ming; Ng, Pauline Yeung; To, Kelvin Kai-Wang; Cheng, Vincent Chi-Chung; Lung, Kwok-Cheung; Hung, Ivan Fan-Ngai; Yuen, Kwok-Yung.
  • Chung TW; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
  • Sridhar S; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
  • Zhang AJ; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China.
  • Chan KH; Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong, China.
  • Li HL; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
  • Wong FK; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
  • Ng MY; Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
  • Tsang RK; Department of Ear, Nose and Throat Surgery, Pamela Youde Nethersole Eastern Hospital, Hong Kong, China.
  • Lee AC; Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong, China.
  • Fan Z; Division of Otolaryngology, Department of Surgery, The University of Hong Kong, Hong Kong, China.
  • Ho RS; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
  • Luk SY; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
  • Kan WK; Department of Pathology, Queen Mary Hospital, Hong Kong, China.
  • Lam SH; Department of Diagnostic Radiology, Pamela Youde Nethersole Eastern Hospital, Hong Kong, China.
  • Wu AK; Department of Diagnostic Radiology, Pamela Youde Nethersole Eastern Hospital, Hong Kong, China.
  • Leung SM; Department of Diagnostic Radiology, Queen Mary Hospital, Hong Kong, China.
  • Chan WM; Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Hong Kong, China.
  • Ng PY; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
  • To KK; Department of Adult Intensive Care, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China.
  • Cheng VC; Department of Adult Intensive Care, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China.
  • Lung KC; Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
  • Hung IF; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
  • Yuen KY; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China.
Open Forum Infect Dis ; 7(6): ofaa199, 2020 Jun.
Article in English | MEDLINE | ID: covidwho-592170
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.
Keywords

Full text: Available Collection: International databases Database: MEDLINE Type of study: Cohort study / Etiology study / Experimental Studies / Observational study / Prognostic study / Reviews / Systematic review/Meta Analysis Topics: Long Covid Language: English Journal: Open Forum Infect Dis Year: 2020 Document Type: Article Affiliation country: Ofid

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Full text: Available Collection: International databases Database: MEDLINE Type of study: Cohort study / Etiology study / Experimental Studies / Observational study / Prognostic study / Reviews / Systematic review/Meta Analysis Topics: Long Covid Language: English Journal: Open Forum Infect Dis Year: 2020 Document Type: Article Affiliation country: Ofid