Prevalence and Reversibility of Smell Dysfunction Measured Psychophysically in a Cohort of COVID‐19 patients

Moein, Shima T.; Hashemian, Seyed Mohammad Reza; Tabarsi, Payam; Doty, Richard L.

BACKGROUND: Considerable evidence suggests that smell dysfunction is common in Coronavirus Disease 2019 (COVID‐19). Unfortunately, extant data on prevalence and reversibility over time are highly variable, coming mainly from self‐report surveys prone to multiple biases. Thus, validated psychophysical olfactory testing is sorely needed to establish such parameters. METHODS: One hundred SARS‐CoV‐2 positive cases were administered the 40‐item University of Pennsylvania Smell Identification Test (UPSIT) in the hospital near the end of the acute phase of the disease. Eighty‐two were retested 1 or 4 weeks later at home. The data were analyzed using analysis of variance and mixed‐effect regression models. RESULTS: Initial UPSIT scores were indicative of severe microsmia, with 96% exhibiting measurable dysfunction; 18% were anosmic. The scores improved upon retest [initial and retest means (95%CIs) = 21.97 (20.84,23.09) & 31.13 (30.16,32.10; p<0.0001)]; no patient remained anosmic. After five weeks from COVID‐19 symptom onset, the test scores of 63% of the retested patients were normal. However, the mean UPSIT score at that time continued to remain below that of age‐ and sex‐matched healthy controls (p<0.001). Such scores were related to time since symptom onset, sex, and age. CONCLUSION: Smell loss was extremely common in the acute phase of a cohort of 100 COVID‐19 patients when objectively measured. About one‐third of cases continued to exhibit dysfunction after five post‐symptom onset weeks. These findings have direct implications for the use of olfactory testing in identifying SARS‐CoV‐2 virus carriers and for counseling such patients in regards to their smell dysfunction and its reversibility. This article is protected by copyright. All rights reserved