Introduction:
Since the onset of the coronavirus disease 2019 (COVID-19) pandemic in Europe, many otolaryngologists have reported patients with a sudden loss of smell.1,2 Olfactory dysfunction is rapidly becoming a key symptom of COVID-19, with more than 66% of patients in Europe and U.S reporting some degree of hyposmia.1,3-6 The loss of smell has been reported to occur before (11.8%), after (65.4%) or at the same time (22.8%) as the onset of other general or otolaryngological symptoms.1 Knowledge around the relationship between olfactory dysfunction and COVID-19 is rapidly evolving. Recently, Yan et al . shown that anosmia seems to be associated with a milder clinical course in patients with COVID-19.6 Moein et al . suggested that 98% of 60 Iranian COVID-19 patients exhibited some olfactory dysfunction on objective testing; only 35% of these patients were aware of hyposmia/anosmia before testing.7 The nuances around olfaction in COVID-19 appear to be associated with different clinical parameters than other symptoms, and, consequently, warrant further investigation.
The objective of this study was to investigate the olfactory dysfunction of COVID-19 patients with subjective validated patient-reported outcome questionnaires and objective psychophysical testing.