Objective evaluation and predictive value of olfactory dysfunction among patients hospitalized with COVID-19

Olfactory dysfunction is a frequent feature of COVID-19. Despite the growing evidence, current knowledge on the subject remains insufficient, so that data obtained with different tools, from multiple centers and in distinct scenarios are welcome. Yet, the predictive value of olfactory dysfunction in terms of the overall prognosis of COVID-19 is unknown. This study aims to evaluate the olfactory function of hospitalized patients with COVID-19 and the impact of the results on their clinical outcomes.

Patients with severe acute respiratory distress syndrome (ARDS) admitted to a university tertiary hospital were recruited and divided into those with ARDS due to COVID-19, and those with ARDS of any other cause. Sociodemographic and clinical data were collected at baseline and the patients had their objective olfactory function evaluated by the Alcohol Sniff Test on admission and during hospital stay. The participants were then followed up until reaching an endpoint: hospital discharge, endotracheal intubation, transfer to the intensive care unit, or death. Patients with COVID-19 were also subgrouped and compared according to their olfactory thresholds and to their overall clinical outcomes. The obtained data was analyzed using R software. Level of significance was set at 0.05.

Eighty-two patients were included (of which 58 had COVID-19). 87.93% of the patients with COVID-19 had diminished olfactory dysfunction on admission. The mean length of hospital stay among patients with olfactory dysfunction was greater (7.84 vs 6.14 days) and nine individuals in this subgroup had poor overall outcomes. None of those with normal olfactory function developed critical COVID-19. The mean olfactory function was significantly worse among patients with COVID-19 and poor outcomes (3.97 vs 7.90 cm, P = .023).

Objective olfactory dysfunction is frequent in ARDS caused by SARS-CoV-2 infection. Patients with longitudinal poorer outcomes present worse olfactory thresholds on admission.