Objective evaluation of odor loss in COVID-19 and other suspected cases

Introduction: COVID-19 is a pandemic disease known with one of the symptoms is sudden onset anosmia. This symptom sometimes may be the only sign of the disease, therefore it must be research widely.
Objective: We aim to evaluate odor dysfunction in COVID-19 patients objectively and safely without any risk of transmitting the disease.
Methods: The odor threshold test was performed on 105 patients hospitalized at the XXXX Training and Research Hospital on the COVID-19 pandemic service before any treatment began. Odor threshold was tested using a modification of the Connecticut Chemosensory Clinical Research Center olfactory function test. COVID-19 signs and symptoms, PCR test results, thorax computed tomography (CT) findings, and length of hospital stay were recorded. Odor tests were scored between 0-8, 0-1 anosmia, 2-3 severely hyposmia, 4 moderate hyposmia, 5 mild hyposmia, 6 and above normosmia.
Results: Forty-one (39%) of the 105 patients were diagnosed with COVID-19 after the PCR results. Patients with an odor threshold score < 5 were classified as “Smell-Impaired Group”, patients with an odor threshold score ≥ 5 were placed in “Smell Intact Group”. The incidence of female patients in smell-impaired group was significantly higher (p ˂ 0.05). The proportion of patients who were PCR-positive for COVID-19 in smell-impaired group was significantly higher (p ˂ 0.05) than in smell intact group. Among patients with an odor threshold score from 0 to 1 (anosmic; n = 15), 12 (80%) demonstrated PCR positivity (p < 0.0001).
Conclusion: Anosmia can be predictive for coronavirus disease. Odor threshold test can be helpful for diagnosis.