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.