Self-reported symptom study of COVID-19 chemosensory dysfunction in Malaysia

Abstract

Alterations in the three chemosensory modalities—smell, taste, and chemesthesis—have been implicated in Coronavirus Disease 2019 (COVID-19), yet emerging data suggest a wide geographic and ethnic variation in the prevalence of these symptoms. Studies on chemosensory disorders in COVID-19 have predominantly focused on Caucasian populations whereas Asians remain understudied. We conducted a nationwide, multicentre cross-sectional study using an online questionnaire on a cohort of RT-PCR-confirmed adult COVID-19 patients in Malaysia between 6 June and 30 November 2020. The aim of our study was to investigate their presenting symptoms and assess their chemosensory function using self-ratings of perceived smell, taste, chemesthesis, and nasal blockage. In this cohort of 498 patients, 41.4% reported smell and/or taste loss when diagnosed with COVID-19, which was the commonest symptom. Blocked nose, loss of appetite, and gastrointestinal disturbances were independent predictors of smell and/or taste loss on multivariate analysis. Self-ratings of chemosensory function revealed a reduction in smell, taste, and chemesthesis across the entire cohort of patients that was more profound among those reporting smell and/or taste loss as their presenting symptom. Perceived nasal obstruction accounted for only a small proportion of changes in smell and taste, but not for chemesthesis, supporting viral disruption of sensorineural mechanisms as the dominant aetiology of chemosensory dysfunction. Our study suggests that chemosensory dysfunction in COVID-19 is more widespread than previously reported among Asians and may be related to the infectivity of viral strains.Study Registration: NMRR-20-934-54803 and NCT04390165.

Assessment of Smell and Taste Disturbances among COVID-19 Convalescent Patients: A Cross-Sectional Study in Armenia

“…Also, we found that the recognition of smells does not decrease proportionately for all fragrances because many study participants found it difficult to recognize the smell of chocolate. However, more scientific studies in this direction would provide more insight into this topic because several other studies found the mechanisms of olfactory disturbances to be either central or peripheral [ 6 , 16 , 25 , 50 ].…”

“…We also investigated the variation in taste perception for all four main flavors based on evidence suggesting that the taste disturbances can be flavor-dependent [ 6 , 51 ]. Our study results also indicate that the COVID-19-associated decline in taste sensation and perception is not uniform in all flavor profiles.…”

“…These neurological signs and symptoms due to COVID-19 infection can be further classified based on the severity of the disease and/or course of infection. Symptoms such as hyposmia/anosmia and hypogeusia/ageusia are commonly found in mild cases, whereas symptoms such as stroke, delirium, and neuronal inflammation are usually reported in severe cases [ 3 , 4 , 5 , 6 ].…”

“…The uncertainty of pathophysiological mechanisms and significant variability in neurosensory dysfunction, such as a loss of smell (hyposmia) and taste (hypogeusia) caused by SARS-CoV-2 have been associated with its neuro-invasion [ 6 , 22 ]. However, there is a scarcity of scientific data related to the prevalence of these symptoms in COVID-19 convalescent patients.…”

Subjective and psychophysical olfactory and gustatory dysfunction among COVID-19 outpatients; short- and long-term results

“…There have been speculations that GD was merely a side effect to OD, while other reports show a high prevalence and a distinct pathogenesis [ 8 – 10 ]. The pathogenesis for OD in COVID-19 is unknown, but it differs from other respiratory infections by being independent of nasal congestion [ 11 , 12 ]. Instead, local inflammation caused primarily by the binding of SARS-CoV-2 virus to the ACE-2 and TMPRSS2 receptors in the sustentacular (non-neural) cells of the olfactory epithelium seems crucial [ 13 , 14 ].…”