Objective Olfactory Evaluation of Self-reported Olfactory Dysfunction in a Case Series of 86 COVID-19 Patients (preprint)

Objective: To investigate olfactory dysfunction in patients with mild COVID-19 through patient-reported outcome questionnaires and objective psychophysical testing. Methods: Adult patients with COVID-19 and self-reported sudden-onset olfactory dysfunction were recruited through a public call for participation from the University of Mons. Demographic data, pathologic conditions, general and otolaryngological symptoms were collected, and general nasal complaints were evaluated with the sino-nasal outcome-22 (SNOT-22). Subjective olfactory and gustatory status was evaluated with the National Health and Nutrition Examination Survey (NHNES) and the short version of the Questionnaire of Olfactory Disorders-Negative Statements. Objective olfactory status was evaluated using an objective psychophysical test (Identification Sniffin Stick test). Results : 86 patients completed the study. The mean age was 42 + or - 12 years. The most common symptoms were fatigue (75%), headache (63%), nasal obstruction (58%), dysgeusia (51%), postnasal drip (49%), cough (49%) and myalgia (46%). On NHNES, total loss of taste and smell were reported by 51% and 74% of patients, respectively. 65% of patients reported a total loss of smell, while the remainder reported a partial loss. Objective olfactory testing found 41 anosmic (48%), 12 hyposmics (14%), and 33 normosmics (38%) patients. There was no correlation between the objective test results and subjective reports of nasal obstruction or postnasal drip, these complaints were absent in 69% of anosmic patients. Conclusion : A significant proportion of patients reporting olfactory dysfunction related to COVID-19 infection do not have olfactory dysfunction on objective testing. Furthermore, a majority of those with measured olfactory dysfunction did not have corresponding nasal obstruction.

Psychophysical Olfactory Findings of Mild-to-moderate COVID-19 Patients: Preliminary Report. (preprint)

Since the onset of the COVID-19 infection, many patients reported sudden loss of smell (SLS). However, due to the lack of psychophysical testings, it remains difficult to know if these patients really have hyposmia or anosmia. Our group investigated the prevalence of anosmia and hyposmia in 28 COVID-19 patients and the potential association with nasal complaints.

Objective olfactory testing in patients presenting with sudden onset olfactory dysfunction as the first manifestation of confirmed COVID-19 infection (preprint)

Abstract Background: The aims of this study are to investigate the COVID-19 status of patients with initial sudden olfactory anosmia (ISOA) using nasopharyngeal swabs for RT-PCR analysis and to explore their olfactory dysfunctions with psychophysical olfactory evaluation. Methodology: This prospective study included 78 ISOA patients who fulfilled a patient-reported outcome questionnaire and underwent a nasopharyngeal swabs. Among these, 46 patients performed psychophysical olfactory evaluation using sniffing tests. Based on the duration of the ISOA, two groups of patients were compared: patients with anosmia duration [≤]12 days (group 1) and those with duration >12 days (group 2). Results: Among group 1, 42 patients (87.5%) had a positive viral load regarding RT-PCR while 6 patients (12.5%) were negative. In group 2, 7 patients (23%) had a positive viral load and 23 patients (77%) were negative. Among the 46 patients having performed a psychophysical olfactory evaluation, we observed anosmia in 52% (N=24), hyposmia in 24% (N=11) and normosmia in 24% (N=11) of patients. The viral load significantly decreased throughout the 14-days following the onset of the olfactory disorder. Conclusions: Our results support that a high proportion of ISOA patients are Covid+. Our study supports the need to add anosmia to the list of symptoms used in screening tools for possible COVID-19 infection.