SynthesisClinical otolaryngology : official journal of ENT-UK ; official journal of Netherlands Society for Oto-Rhino-Laryngology & Cervico-Facial Surgery2020
Is loss of sense of smell a diagnostic marker in COVID-19: A systematic review and meta-analysis.
Synthesis in Clinical otolaryngology : official journal of ENT-UK ; official journal of Netherlands Society for Oto-Rhino-Laryngology & Cervico-Facial Surgery, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 105 papers, 10 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
105 citing papers in PubMed, 10 syntheses or guidelines pooled it.
- Qualitative Olfactory Dysfunction and COVID-19: An Evidence-Based Review with Recommendations for the Clinician.American journal of rhinology & allergy · 2023Pooled it
- Taste loss as a distinct symptom of COVID-19: a systematic review and meta-analysis.Chemical senses · 2023Pooled it
- Interventions for the treatment of persistent post-COVID-19 olfactory dysfunction.The Cochrane database of systematic reviews · 2022Pooled it
- Interventions for the prevention of persistent post-COVID-19 olfactory dysfunction.The Cochrane database of systematic reviews · 2022Pooled it
- Prognosis and persistence of smell and taste dysfunction in patients with covid-19: meta-analysis with parametric cure modelling of recovery curves.BMJ (Clinical research ed.) · 2022Pooled it
- Hearing Loss, Tinnitus, and Dizziness in COVID-19: A Systematic Review and Meta-Analysis.The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques · 2022Pooled it
- Interventions for the prevention of persistent post-COVID-19 olfactory dysfunction.The Cochrane database of systematic reviews · 2021Pooled it
- Interventions for the treatment of persistent post-COVID-19 olfactory dysfunction.The Cochrane database of systematic reviews · 2021Pooled it
- Is loss of sense of smell a diagnostic marker in COVID-19: A systematic review and meta-analysis.Clinical otolaryngology : official journal of ENT-UK ; official journal of Netherlands Society for Oto-Rhino-Laryngology & Cervico-Facial Surgery · 2020Pooled it
- Prevalence of Chemosensory Dysfunction in COVID-19 Patients: A Systematic Review and Meta-analysis Reveals Significant Ethnic Differences.ACS chemical neuroscience · 2020Pooled it
- Point-of-care smell testing for evaluation of olfactory function: a narrative review of clinical utility.Frontiers in allergy · 2026Review
- Effects of pulsed and continuous ultrasound therapy on olfactory disorders in COVID-19 patients.Iranian journal of microbiology · 2025Article
- Oral health, smoking status, and oral manifestations of adult patients with SARS-CoV-2 during the Omicron outbreak in China: a cross-sectional study.Scientific reports · 2025Article
- Review
- Clinical Course and Mortality Predictors in Adult Hospitalized Patients with COVID-19 Infection-A Retrospective Cohort Study.Medicina (Kaunas, Lithuania) · 2025Article
- Comparison Between Intranasal Insulin Films Alone and Combined Intranasal Insulin Plus Steroid Films for Post Viral Olfactory Dysfunction.Indian journal of otolaryngology and head and neck surgery : official publication of the Association of Otolaryngologists of India · 2025Article
- White matter changes in recovered COVID-19 patients: insights from DTI, DKI, and NODDI metrics.Frontiers in neurology · 2025Article
- The digital scent device 20: an automated, self-administered odor identification test.European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery · 2024Article
- Treatments for Olfactory Dysfunction in COVID-19: A Systematic Review.International archives of otorhinolaryngology · 2024Review
- Chemosensory assessment and impact on quality of life in neurosensorial cluster of the post COVID 19 syndrome.Scientific reports · 2024Article
45 more citing papers are in PubMed but not listed here.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
4 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
aimsTo systematically review the currently available evidence investigating the association between olfactory dysfunction (OD) and the novel coronavirus (COVID-19). To analyse the prevalence of OD in patients who have tested positive on polymerase chain reaction (PCR) for COVID-19. To perform a meta-analysis of patients presenting with olfactory dysfunction, during the pandemic, and to investigate the positive predictive value for a COVID-19-positive result in this population. To assess whether olfactory dysfunction could be used as a diagnostic marker for COVID-19 positivity and aid public health approaches in tackling the current outbreak.
methodsWe 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. A total of 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.
resultsOlfactory dysfunction 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.
conclusionOur 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.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.