Is loss of smell an early predictor of COVID-19 severity: a systematic review and meta-analysis

Purja, Sujata; Shin, Hyun-June; Lee, Ji Yun; Kim, Eun Young

doi:10.1007/s12272-021-01344-4

Cited by 31 publications

(24 citation statements)

References 88 publications

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“…The findings of the study may be counterintuitive to many since increased viral load would be expected to lead to more widespread damage to the olfactory and gustatory epithelium. Nevertheless, the observations coincide with the findings of a meta‐analysis 2 in which severely ill patients with COVID‐19 had a lower odd of experiencing OD than non‐severely ill patients with COVID‐19 (odds ratio=0.527; 95% confidence interval 0.373–0.744); the viral loads have been associated directly with disease severity in patients with COVID‐19, and therefore, patients with OD and/or GD who had a low viral load (as reported in the study 1 ) would be expected to experience milder illness. 3 …”

supporting

confidence: 87%

Physiological plausibility of lower viral load in patients with COVID‐19 and olfactory/gustatory dysfunction

Kow

Ramachandram

Hasan

2021

Clinical Otolaryngology

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supporting

confidence: 87%

Physiological plausibility of lower viral load in patients with COVID‐19 and olfactory/gustatory dysfunction

Kow

Ramachandram

Hasan

2021

Clinical Otolaryngology

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“…82,83 Multiple studies and reviews agree that disease severity is negatively associated with anosmia prevalence. 1,[83][84][85] Finally, objective methodology to assess olfactory dysfunction may be more sensitive than subjective recall, resulting in an increased prevalence, although studies are controversial. 7 Response bias may occur if early studies did not inquire about olfactory dysfunction as much as later studies.…”

Section: Effects Of Response Bias Age Disease Severity Gender and Methodologymentioning

confidence: 99%

The D614G virus mutation enhances anosmia in COVID-19 patients: Evidence from a systematic review and meta-analysis of studies from South Asia

Bartheld

Hagen

Butowt

2021

Preprint

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The prevalence of chemosensory dysfunction in patients with COVID-19 varies greatly between populations. It is unclear whether such differences are due to factors at the level of the human host, or at the level of the coronavirus, or both. At the host level, the entry proteins which allow virus binding and entry have variants with distinct properties, and the frequency of such variants differs between ethnicities. At the level of the virus, the D614G mutation enhances virus entry to the host cell. Since the two virus strains (D614 and G614) co-existed in the first six months of the pandemic in most populations, it has been difficult to distinguish between contributions of the virus and contributions of the host for anosmia. To answer this question, we conducted a systematic review and meta-analysis of studies in South Asian populations when either the D614 or the G614 virus was dominant. We show that populations infected predominantly with the G614 virus had a much higher prevalence of anosmia (pooled prevalence of 31.8%) compared with the same ethnic populations infected mostly with the D614 virus strain (pooled anosmia prevalence of 5.3%). We conclude that the D614G mutation is a major contributing factor that increases the prevalence of anosmia in COVID-19, and that this enhanced effect on olfaction constitutes a previously unrecognized phenotype of the D614G mutation. The new virus strains that have additional mutations on the background of the D614G mutation can be expected to cause a similarly increased prevalence of chemosensory dysfunctions.

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“…The mean age of the patients seen in the clinic was 54.3 years, standard deviation 16.2. The median age of the respiratory clinic patients was 55 years; although olfactory dysfunction normally increases with age, in COVID-19 patients increasing age is correlated with lower prevalence of olfactory dysfunction (2), and lack of anosmia is associated with higher risk of severe illness and death in hospitalized patients(3, 14, 15). Uninfected patients in the current sample of patients over the age of 40 had 1.65 higher than expected incidence of anosmia; SARS-CoV-2 infection was associated with anosmia incidence ∼3.9 times higher than expected from the NHANES study (Table 2).…”

Section: Resultsmentioning

confidence: 99%

“…The risk of anosmia was 2.40 times greater if a patient displayed SARS-CoV-2 positivity (p= 0.0016, two tailed; Table 1). (2), and lack of anosmia is associated with higher risk of severe illness and death in hospitalized patients (3,14,15).…”

Section: (Which Was Not Certified By Peer Review)mentioning

confidence: 99%

Detection of COVID-19 and age-dependent dysosmia with paired crushable odorant ampules

Wood

Stodgell

Linder

et al. 2022

Preprint

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Background Signs of anosmia can help detect COVID-19 infection when testing for viral positivity is not available. Inexpensive mass-produced disposable olfactory sensitivity tests suitable for worldwide use might serve not only as a screening tool for potential infection but also to identify cases at elevated risk of severe disease as anosmic COVID-19 patients have a better prognosis. Methods and Findings We adopted paired crushable ampules with two concentrations of a standard test odorant (n-butanol) as standard of care in several clinics as community prevalence of COVID-19 infection waxed and waned. This was not a clinical trial; a chart review was undertaken to evaluate the operating characteristics and potential utility of the test device as RT-PCR testing became routine. The risk of anosmia was greater in COVID-19 patients. Olfactory sensitivity was concentration-dependent and decreased with aging. Hyposmia was detected across a wider age range than expected from the literature, and tests can be optimized to characterize different age groups. Conclusions n-Butanol at 0.32 and 3.2% in crushable ampules can be used to characterize olfactory function quickly and inexpensively and thus has potential benefits in pandemic screening, epidemiology, and clinical decision-making.

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Is loss of smell an early predictor of COVID-19 severity: a systematic review and meta-analysis

Abstract: monitored more closely in the early stages of COVID-19, for early diagnosis of severity of illness. An understanding of how the severity of COVID-19 infection and LOS are associated has profound implications for the clinical management and mitigation strategies for the disease.

Cited by 31 publications

References 88 publications

Physiological plausibility of lower viral load in patients with COVID‐19 and olfactory/gustatory dysfunction

Physiological plausibility of lower viral load in patients with COVID‐19 and olfactory/gustatory dysfunction

The D614G virus mutation enhances anosmia in COVID-19 patients: Evidence from a systematic review and meta-analysis of studies from South Asia

Detection of COVID-19 and age-dependent dysosmia with paired crushable odorant ampules

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