Comparison of subjective olfactory dysfunction with results from psychophysical testing in patients with COVID-19 infection over the long-term course

Background COVID-19 induced olfactory dysfunction was reported as a subjective symptom by approximately 48% of patients until the end of 2021. In psychophysical testing an often-unnoticed olfactory impairment could be measured in up to 98% of patients. The aim of this study is to compare the subjectively altered olfactory performance with the results from psychophysical tests at several examination time points.

Methods This prospective study examined 63 patients (17♂, 46♀, age: ø42±13 years) with subjective olfactory impairment after COVID-19 infection already persisting for an average of nine months at the time of initial presentation. Follow-up examinations were performed at an average of six and ten weeks after initial presentation. Data collection included subjective patient information and side-separated olfactory testing using Sniffin’ Sticks (SDI). The subjective patient data were compared with the psychophysical testing.

Results At initial presentation, 10% of patients with subjective olfactory impairment had normosmia in psychophysical testing. At the first follow-up examination, 55% reported subjective improvement in findings. Objectively, 65.5% measured an improvement in findings. At the second follow-up examination 54% reported subjective improvement in findings and objective improvement was measured in 57.5%. There was no significant correlation between subjective and objective olfactory impairment at any point.

Discussion According to the literature, subjective assessment of olfactory dysfunction correlates most closely with objective olfactory testing in the acute stage. Especially in the long-term course, psychophysical tests can depict an individual recovery of the sense of smell better and should therefore be preferred for the assessment of olfaction.

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Artikel online veröffentlicht:
12. Mai 2023