Objective and subjective olfactory dysfunction among COVID-19 inpatients and controls: a prospective, case-control study

This is the authors' abstract. We don't add key points for this paper.

Introduction: Olfactory dysfunction associated with COVID-19 infection is frequently described, but few studies utilize validated, objective tests or a control group. We compared rates of olfactory dysfunction between adults hospitalized with COVID-19 and controls admitted with similar upper respiratory symptoms who were COVID-19-negative. Methods: Hospitalized (general ward) adults with upper respiratory symptoms who tested PCR positive or negative for SARS-CoV-2 completed the objective Brief Smell Identification Test (BSIT; ≥9 correct=normal) and subjective assessments while hospitalized and again at 3 month follow up. Comparison of groups was performed by t test or chi-square test of independence. Results: There were no differences in mean age or gender between groups (n=26 COVID, n=28 control). Both groups demonstrated objective olfactory dysfunction (mean BSIT 7.9 ± 2.8 COVID vs. 8.3 ± 3.2 control, p=0.62). Rates of both objective and subjective dysfunction did not significantly differ between groups. Follow up data at 3 months was limited (n=6 COVID, n=5), but showed 50% olfactory dysfunction in COVID patients compared to 20% in controls. Conclusions: SARS-CoV-2 and other viral illnesses serious enough to cause hospitalization cause olfactory dysfunction. Better understanding of the trajectory of chemosensory recovery will help elucidate the pathophysiology of viral-associated olfactory dysfunction and inform the care of patients suffering from its sequelae.