Smell dysfunction: a biomarker for COVID-19

Area of Science:

• Otolaryngology
• Infectious Diseases
• Neurology

Background:

• Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) causes COVID-19, a pandemic with recognized symptoms like cough, fever, and breathing difficulties.
• Patient-reported smell and taste loss is linked to COVID-19, but empirical olfactory testing has been lacking.

Purpose of the Study:

• To quantitatively assess olfactory dysfunction in COVID-19 patients.
• To determine the prevalence and severity of smell loss in confirmed SARS-CoV-2 infections.
• To compare olfactory function between COVID-19 patients and matched controls.

Main Methods:

• Administered the University of Pennsylvania Smell Identification Test (UPSIT) to 60 COVID-19 inpatients and 60 controls.
• The UPSIT is a validated 40-odorant test assessing olfactory function.
• Used mixed effects analysis of variance to compare test scores between groups and analyze sex influence.

Main Results:

• 98% of COVID-19 patients (59/60) exhibited smell dysfunction, with a mean UPSIT score of 20.98 compared to 34.10 in controls (p < 0.0001).
• 58% of patients were anosmic or severely microsmic; deficits were observed across all 40 tested odorants.
• No significant correlations were found between olfactory test scores and sex, disease severity, or comorbidities.

Conclusions:

• Quantitative smell testing confirms decreased smell function as a significant marker for SARS-CoV-2 infection.
• Olfactory dysfunction, ranging from mild to anosmia, is highly prevalent in COVID-19 patients.
• Smell testing may aid in identifying COVID-19 patients requiring early intervention or quarantine.