Relationship between olfactory function and quality of life in COVID-19 patients

COVID-19 is associated with multiple long-term impairments that negatively affect patients' quality of life (QoL). Of these, olfactory dysfunction (OD), which is difficult to measure in practice, is likely to play an important role as it highly affects peoples’ QoL.

In a population-based study, a total of 667 adult participants (mean age: 47 years) were examined nine months, on average, after positive PCR testing for SARS-CoV-2. Subjective olfactory function (OF) was quantified by means of a Visual Analogue Scales (OF-VAS). OF was tested by way of the Sniffin’ Sticks Test (SST). The self-reported Mini Olfactory Questionnaire (self-MOQ) was used to screen for OD. The brief (short) version of the Questionnaire of Olfactory Disorders - Negative Statements (sQOD-NS), the sinonasal outcome Test-22 (SNOT-22), the EuroQoL 5-Dimension 5-Level (EQ-5D-5L), and the EuroQoL-VAS (EQVAS) were used to assess QoL.

Participants with SST-tested OD or with OF-VAS-based subjective OD were characterized by significantly higher self-MOQ scores. Diagnoses of OD by self-MOQ or SST were found to be strongly correlated. Moreover, both the TDI score and the OF-VAS score were negatively correlated with the self-MOQ score. In addition to a significant reduction of QoL in participants with tested OD, the four questionnaires used in the present study also consistently highlighted a significant negative correlation between QoL and both, self-MOQ and OF-VAS score.

The self-MOQ is a sufficient screening tool for OD after SARS-CoV-2 infection. Patients with persistent OD show signi-ficantly poorer QoL than those without.

Olfactory function can be assessed in patients with COVID-19 using a simple 5-item questionnaire (self-MOQ). Patients with OD show reduced QoL.

In our population-based cross-sectional study of 667 patients with PCR-confirmed SARS-CoV-2 infection, par-ticipants with persistent OD had significantly poorer OF-related QoL. The self-MOQ is a simple, valid and reliable means to screen OD in patients with COVID-19.