Methods:
This study was cross-sectional study, and took place at “Blind for review”.
Participants of the study were 16 people (11 of 16 were women, 69%), with a median age of 42 years (interquartile range 15–83), self-reporting of prolonged (lasting more than four weeks) impairment in odor sensation, and visiting the outpatient clinic at “Blind for review” from December 2020 to January 2022. Clinical data from their medical records were collected, including symptoms, laboratory variables, endoscopy and CT findings, and final diagnosis. The outcome was the pattern and severity of odor sensation impairment. The following methods were used to assess the outcome qualitatively and quantitatively. (i) Participant completed the Self-Administered Odor Questionnaire (SAOQ), which was developed by the Japan Rhinology Society to assess an individual’s ability to identify 20 different odorants. The percentage of correct answers indicated the degree of impairment3. (ii) The Open Essence (OE) smell identification card assessed an individual’s ability to identify 12 different odorants familiar to the Japanese population. The number of correct answers reflected the severity of impairment4. (iii) Intravenous olfactometry (IO) measures the latency in recognizing the garlic-like odor and the duration of its perception, following an injection of thiamine propyl-disulfide. The worst score was used for analysis of participants who were assessed longitudinally at multiple time points. This study was approved by the institutional review board of “Blind for review”. All participants have given their informed consent to participate.
Participants were assessed for the etiology of their POD. They were tested for anti-SARS-CoV-2 antibodies using the Elecsys Anti-SARS-CoV-2 assay (Roche, Basel, Switzerland). One participant with a “high-negative” result was further tested with the Architect SARS-CoV-2 IgG and IgG II Quant (Abbott, Chicago, Illinois, USA) immunoassays, targeting nucleocapsid and spike proteins, respectively. In the absence of a SARS-CoV-2 vaccination, the participant had “positive” results on both confirmatory immunoassays and was thus classified as having a positive serology. Participants with positive serology against SARS-CoV-2 were diagnosed with COVID-19-related POD. CT was used to diagnose paranasal sinus abnormalities. Non-SARS-CoV-2 post-viral POD was defined as a persistent impairment in odor sensation after recovery from acute rhinitis. Participants with POD were otherwise classified as “idiopathic.”
The Strengthening the Reporting of OBservation studies in Epidemiology statement was used to report the findings.