Asymptomatic olfactory dysfunction in nonintubated patients with moderate and severe COVID-19

ABSTRACT

Objective: To evaluate the frequency of asymptomatic olfactory dysfunction (OD) in nonintubated patients with moderate and severe coronavirus disease 2019 (COVID-19). Background: Many patients with COVID-19 reported OD. However, most studies relied on selfreported data. A few studies have recently used olfactory psychophysical assessment tools, but it is difficult to implement such strategies in a real-life setting. Asymptomatic OD (aOD) has been anecdotally reported during the early stages of COVID-19. Nevertheless, there is currently no study focusing on the prevalence of OD clinically identified through a typical neurologic examination in those patients with COVID-19 who denied this symptom during history taking. Design/Methods: Adult inpatients at the Hospital Juárez de México (Mexico City) were recruited if they were nonintubated and SARS-CoV-2 was detected by real-time RT-PCR in any biological specimen. Olfactory function was assessed using a widely known technique in general neurologic practice. Standard definitions were also taken from the same authoritative source. COVID-19 severity was classified according to Gandhi et al (2020). Results: 23 patients (10 women) were included. The mean age was 45.7±13.6 years. Only five patients reported OD during history taking. Of those who denied this symptom (n = 18), any OD was identified in 8 patients through neurologic examination (44.4%). Two of these patients with aOD reported taste impairment during focused history taking. No differences according to gender were found in OD identified through neurologic examination. OD prevalence increased from 21.7% using history taking alone to 56.5% with the addition of a standard neurologic examination (difference 34.7%;P = 0.007). Conclusions: In daily practice, simply asking for OD may not be enough to detect this impairment in nonintubated patients with moderate and severe COVID-19. If these findings can be replicated in further studies, consideration should be given to modify our current screening strategies for OD during the COVID-19 pandemic.