Introduction
With the emergence of Coronavirus disease 2019 (COVID-19) outbreak on December 20191, many researches have been published about its transmission, diagnosis, clinical presentation and management. Its presentation varies widely from mild to severe symptoms including severs pneumonia. Though the main reported COVID-19 symptoms include fever, headache, gastrointestinal symptoms, and respiratory symptoms.2 Upper respiratory symptoms where not uncommon such as sore throat, rhinorrhea, complete or partial loss of smell (olfactory dysfunction-OD).3 Post viral Olfactory dysfunction (PVOD) Is caused by different viruses including Rhinoviruses, coronaviruses, parainfluenza viruses, and Epstein‐Barr viruses.4 Many preliminary reports have suggested that smell and taste loss are potential early symptom or subclinical markers of COVID‐19 infection. Several cross-sectional studies from many countries such as Iran, United Kingdom, Italy, Spain, Germany, European countries, France, and united states have been published about OD prevalence in COVID-19 patients.5,6 The incidence of OD in COVID-19 patients differs widely between these cross-sectional studies. ranging from 33.9 to 68%.5
A study from Spain using a self-reported questionnaire only without a validated olfactory test, found that the incidence rate of OD in COVID-19 patients was significantly more than OD in influenza patients (39.2% vs12.5%).7 Olfactory tests are categorized in to 3 types: subjective, psychophysical, and electorophysiological studies. Subjective testing can be performed through self-reporting method or as a part of quality of life outcome questionnaire eg. Sinonasal outcome test-22 (SNOT-22). Many tests have been utilized to assess the olfaction function objectively. These are the psychophysical tests which measure some or all the three olfactory parameters: the threshold, discrimination and identification. While subjective and psychophysical tests are used in most clinical and research, the electrophysiological studies like electroencephalography (EEG) and electro-olfactography (EOG) are having limited clinical use and mainly performed for medicolegal issues.8
One observational study from Saudi Arabia, found that self- reported loss of taste and smell was the most common presentation (47.5%.) in mild symptomatic COVID-19 patients.9 Objective (psychophysical test) has been available in few studies only, though it is considered to be the gold standard for diagnosis of OD.2,10,11 Moein et al reported that only 35% of their subjects were aware about their smell problem before doing objective test which indicate that self-reporting of the symptoms may be not enough and the incidence rate of OD is much higher than reported by the previous studies.10
This study aims to use Quick Smell Identification Test (Q-SIT) as screening tool to assess the prevalence of olfactory dysfunction in patients with confirmed COVID-19 infection in Qatif area, Eastern province, Saudi Arabia.