Comment to the article "Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study".

Dear Editor,

We read with interest the paper: “Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study” by Lechien et al. [1] published on your Journal.

The involvement of the olfactory tract by viruses is well known and even preliminary reports on Chinese patients attested that around 10–15% of Covid-19 positive hospitalized patients presented olfactive and/or gustative disorders [2].

Lechien et al. [1] claim that a percentage as high as 85–88% of the patients affected by Sars-CoViD2 who underwent a validated questionnaire reported olfactory or gustative disorders.

Authors used a short version of the Questionnaire of Olfactory Disorders-Negative Statements, a tool mostly focused to identify psychologic impairment due to olfactory dysfunction than the olfactory impairment itself; moreover, the social anxiety, annoyance, and eating questions are possibly severe confounding factors in patients hospitalized, isolated, and concerned about their health in a pandemic scenario.

In our University Hospital, the anamnestic interview of patients transited in the Covid-19 inpatient wards revealed olfactory disorders in 25–30% of affected individuals. This figure is close to the data reported by Giacomelli et al. [3] in 60 patients. In this group, 39% reported olfactory or gustatory disorders in a questionnaire including olfactory and taste disorders [3].

Our convincement is that the use of a questionnaire focused on the psychologic and social burden of olfactory disorders, especially in the context of a pandemic scenario and the consequent restrictions in social life, might lead to overestimation. When the situation (risks and emergency contingencies) does not allow to investigate olfaction with validated and more objective tests, in our view, it is advisable to use a questionnaire directly focused on the symptoms, both nasal and olfactory ones.