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Psychophysical Testing of Chemosensory Function During COVID-19 Infection Shows Recovery Trend

by Linda Kossoff •

What will extensive psychophysical tests performed during the course of COVID-19 disease reveal about chemosensory dysfunction and recovery?

BOTTOM LINE

Chemosensory dysfunction is very common in COVID-19 and, although most people regain function within the first 28 days, a quarter of patients show persisting chemosensory dysfunction.

BACKGROUND: Although smell and taste dysfunction are among the most common symptoms of COVID-19, most studies on chemosensory dysfunction in COVID-19 are based on subjective findings. Objective psychophysical tests done during the infection could provide a reliable evaluation of chemosensory function and recovery over the course of the disease.

STUDY DESIGN: Prospective cohort study.

SETTING: Smell and Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Germany; Center for Rhinology and Allergology, Wiesbaden, Germany; Department of Otolaryngology, Head and Neck Surgery, Munich Clinic Schwabing, Academic Teaching Hospital, Ludwig-Maximilians University, Munich, Germany; and Department of Otolaryngology, University of Foggia, Italy.

SYNOPSIS: Researchers conducted chemosensory tests on 111 confirmed COVID-19 patients (59 males, 52 females, mean age 44.5 years). Participants were tested within three days of diagnosis, and at different time points according to each location’s schedule (mean days post infection 62.9 days). Two methods of gustatory testing were used, as available: the simple Taste Sprays tool and the more detailed Taste Strips. For testing olfactory function, examiners used two evaluation methods by Sniffin’ Sticks for threshold, discrimination, and identification abilities, as available on site. Statistical analysis revealed significant differences in olfactory function during infection (21% anosmic, 49% hyposmic, 30% normosmic) and after infection (1% anosmic, 25% hyposmic, 74% normosmic). Gustatory function tested with Taste Strips also showed significant differences during and after infections; Taste Spray screening results did not. Combined, gustatory tests showed a functional reduction from 26% during infection to 6.5% post infection. Results indicated that most people with COVID-19-associated chemosensory dysfunction regain smell and taste within 28 days, but up to a quarter of patients exhibit a longer-lasting dysfunction. Limitations included a limited number of participants for detailed gustatory function testing.

CITATION: Niklassen AS, Draf J, Huart C, et al. COVID-19: Recovery from chemosensory dysfunction. A multicentre study on smell and taste. Laryngoscope. 2021;131:1095-1100.