Smell and Taste Disorder Differences Seen Between Long-Term COVID-19 and non-COVID-19 Patients

by Linda Kossoff •

How do the smell and taste disorders of both simple and complex post-COVID-19 cases differ from those of matched non-COVID-19 post-infection cases?

BOTTOM LINE

Smell and taste function differ significantly between post-COVID-19 patients and non-COVID-19 post-viral patients.

BACKGROUND: Olfactory dysfunction is a common symptom occurring in mild to moderate COVID-19 that may persist post-infection. Taste dysfunction is seen less frequently but occurs and persists. Other upper respiratory tract viruses may also cause post-infectious olfactory disorders and taste disorders. Literature exploring differences among these patient groups is sparse.

STUDY DESIGN: Matched cohort study.

SETTING: University Clinic for Flavour, Balance and Sleep, ENT Department, Goedstrup Hospital, Herning, Denmark.

SYNOPSIS: Researchers separated patients suffering from post-COVID-19 symptoms into two case groups: 1) simple post-COVID-19, with smell and taste disorder as the only long-term post-infectious complaint, and 2) complex post-COVID-19, with long-term post-infectious complaints in addition to smell and taste disorders. A non-COVID-19 post-infectious group with smell loss was identified and matched by duration of smell and taste disorders. In addition to patient-reported outcome measures, quality-of-life score, ear-nose-throat examination, Mini-Mental State Examination, orthonasal smell test, retronasal quick test, and taste screening were used. Results showed that, compared with non-COVID-19 post-infectious cases, patients with COVID-19–related, long-term smell and taste disorders were younger, had a lower occurrence of anosmia/ageusia, more often experienced distorted senses, and had higher threshold, discrimination, and identification scores. Authors state that, given recent evidence that recovery may occur later than 12 weeks post-infection, more long-term follow- up studies are needed to establish a prognosis and definition of chronic olfactory loss. Study limitations included possible patient selection bias.

CITATION: Stankevice D, Fjaeldstad AW, Agergaard J, et al. Long-term COVID-19 smell and taste disorders differ significantly from other post-infectious cases. Laryngoscope. 2023;133:169-174.