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Is loss of sense of smell as a diagnostic marker in COVID-19: A Systematic Review and Meta-analysis
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  • John Rocke,
  • Claire Hopkins,
  • Carl PhilpottOrcid,
  • B. Nirmal Kumar
John Rocke
Royal Albert Edward Infirmary, Wigan
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Claire Hopkins
University Hospital Lewisham
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Carl Philpott
Orcid
University of East Anglia
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Medium
B. Nirmal Kumar
WWL NHS Trust
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Peer review status:ACCEPTED

20 Apr 2020Submitted to Clinical Otolaryngology
22 Apr 2020Submission Checks Completed
22 Apr 2020Assigned to Editor
03 May 2020Reviewer(s) Assigned
26 May 2020Editorial Decision: Revise Minor
26 May 20201st Revision Received
28 May 2020Submission Checks Completed
28 May 2020Assigned to Editor
18 Jun 2020Reviewer(s) Assigned
24 Jun 2020Review(s) Completed, Editorial Evaluation Pending
02 Jul 2020Editorial Decision: Revise Minor
04 Jul 20202nd Revision Received
05 Jul 2020Submission Checks Completed
05 Jul 2020Assigned to Editor
14 Jul 2020Reviewer(s) Assigned
17 Jul 2020Review(s) Completed, Editorial Evaluation Pending
21 Jul 2020Editorial Decision: Accept

Abstract

Aims 1. To systematically review the currently available evidence investigating the association between olfactory dysfunction (OD) and the novel coronavirus (COVID-19). 2. To analyse the prevalence of OD in patients who have tested positive on Polymerase Chain Reaction (PCR) for COVID-19. 2. To perform a meta-analysis of patients presenting with olfactory dysfunction, during the pandemic, and to investigate the Positive Predictive Value for a COOVID-19 positive result in this population. 3. To assess if olfactory dysfunction could be used as a diagnostic marker for COVID-19 positivity and aid public health approaches in tackling the current outbreak. Methods We systematically searched MedLine (PubMed), Embase, Health Management Information Consortium (HMIC), Medrxiv, the Cochrane Library, the Cochrane COVID-19 Study Register, NIHR Dissemination centre, Clinical Evidence, National Health Service Evidence and the National Institute of Clinical Excellence to identify the current published evidence which associates coronaviridae or similar RNA viruses with anosmia. The initial search identified 157 articles. 145 papers were excluded following application of our exclusion criteria. The 12 remaining articles, that presented evidence on the association between COVID-19 and olfactory dysfunction, were critically analysed. Results OD has been shown to be the strongest predictor of COVID-19 positivity when compared to other symptoms in logistic regression analysis. In patients who had tested positive for COVID-19 there was a prevalence of 62% of OD. In populations of patients who are currently reporting OD there is a positive predictive value of 61% for a positive COVID-19 result. Conclusion Our review has shown that there is already significant evidence which demonstrates an association between OD and the novel coronavirus – COVID-19. It is unclear if this finding is unique to this coronavirus as individual viral phenotypes rarely present in such concentrated large numbers. We have demonstrated that OD is comparatively more predictive for COVID-19 positivity compared to other associated symptoms. We recommend that people who develop OD during the pandemic should be self-isolate and this guidance should be adopted internationally to prevent transmission.